Mixed exhaust vents: Wind turbines and ridge vent

Mixed exhaust vents: Wind turbines and ridge vent

People who know me hear this often: “Don’t Over-Think It”. Things are usually never as complicated as they seem. Of all the questions I get from customers, Attic Ventilation is probably the most misunderstood, and overcomplicated topic in the home efficiency/improvement area. So hear me now: “DON’T OVER-THINK IT”

Attic ventilation is VERY simple. You have HOLES in the bottom of your attic (usually soffit vents) and HOLES in the top of your attic (ridge vent, wind turbines, static vents or power fans). Ideally, air comes IN the bottom and OUT the top. It’s just like a chimney in your home. Pretty simple. Holes in bottom, holes in top…got it?

Think about this. If I came to your home today and started ripping out your soffits and cutting lots of holes in the top of your roof eventually the air temperature in the attic would get close to whatever the outside (ambient) air temperature is. Air temperatures would drop but surface temperatures would not drop much due to the radiant heat gain. A radiant barrier works together with decent attic ventilation to drop both air temperature and surface temps.

Here is where many people screw up attic ventilation. More is not always better. The thought process goes something like this: “If I add an electric or solar attic fan, or some ridge vents, or a few wind turbines or static vents or maybe ALL OF THEM, I’ll move more air and my attic will be cooler” WRONG!!!!

Dirty or clogged soffit vent

Dirty or clogged soffit vent

Let me ask you. Have you EVER seen a chimney with a fan sticking out the side in the MIDDLE? Of course not, why? Common sense would say that the fan would pull air from BOTH the top and bottom of the chimney. Your attic is EXACTLY the same. Why on earth put an electric fan 15” away from a ridge vent or wind turbine? Yes, there will be great airflow in the top 2 feet of the attic and the rest of the air will be almost stagnant.

Air always travels the path of least resistance. Mixing exhaust vents is a bad thing. The strongest vent will dominate and the other exhaust vents will probably become INTAKE vents. This short-circuits the whole concept of air coming in the bottom and out the top. This can happen many different ways from actually mixing different types of exhaust vents to having ridge vents on EVERY ridge. Usually the ridge vents about halfway up the roof will become the intake vents and totally short circuit any air coming from the soffit vents. All the exhaust vents should be within a few feet of each other from the top.

How to fix it? Start at the bottom with your soffit vents. Have you EVER cleaned your soffit vents? 95% of homes have clogged, blocked or painted over soffit vents. Or, the holes behind the vents are so small virtually no air is coming into the attic. I’ve even seen million dollar homes where they just screwed in the vents and did not bother to even cut holes. I’ve seen many homes where just cleaning the soffit vents (use a dry nylon car wheel brush) will drop the attic temperature 20º in 20 minutes. And those wind turbines that were “broken” start spinning like crazy. Get it? Air comes in and now air will go out.

Hole cut too small behind soffit vent

Hole cut too small behind soffit vent

Next, pick one type of exhaust vent and go with it. By combining a basic strategy of holes in top and bottom your attic will be cooler in the Summer and drier in the Winter. Remember, keep it simple, and don’t over-think it…Holes in the bottom, holes in the top.

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250 Comments to “Attic Ventilation – Don’t Mess It Up”

  1. Toff says:

    I agree completely!!! Ventilate, ventilate, ventilate! when I crawl up into the attic of an older home, I notice that there is never enough air flow. usually there is one or two roof vents and a very few soffit vents. One of the more successful experiments I have done, is to take an AC booster fan (~25watt) and secure it into the existing roof vents while adding more soffit vents. In the middle of summer, there is a difference between passive and active air flow. I prefer passive, but some homes just need a little extra help. If you figure out the basic air-in, air-out flow, then adding a little fan (with a thermostat) can help get rid of the heat faster than waiting for the heat to rise. I don’t like the huge 175 watt roof fans due to the amount of electricity they use and the fact that you can never get enough air into the attic through the soffits to keep the fans from pulling your good AC from the house into the attic.

    I usually stick with my passive vents and occasionally use a booster fan when really needed.

    Toff

  2. Kevin says:

    Okay, after reading this, I’m canceling my ridge vent project. I have four exhaust vents a few feet from the top of my roof and my soffits are not clogged, so I’m fine. I cut holes in the radiant barrier by the exhaust vents just as your website instructed. Thanks for the help.
    Kevin in Sugar Land

  3. Zark says:

    Attic vents? I haven’t vented an attic in over 10 years. Unvented attic… foam insulation against the roof line. Radient barrier with air space under a metal roof.

    • Ed Fritz says:

      I totally agree. My first choice is a full foam enclosed non-vented attic with a radiant barrier to the outside as you mention. Unfortunately, this is usually only a cost effective option for new construction. This is for the millions of existing homes that have vented attics. Thanks for the feedback!!

  4. alison says:

    I am now very confused. My understanding is that you must have a ventilated attic for the radiant barrier to be effective. The house I’m working on is essencially a new build. So do I plug the holes or vent the rood?

    • Ed Fritz says:

      No, you want a ventilated attic. Zark and I were referring to using spray foam an fully enclosing an attic. This is done to move the “thermal enclosure” to the outside and bring all ductwork inside a semi-conditioned space and you would have no insulation on your attic floor. Talk to your builder about this technique or check out: http://www.buildingscience.com.....aled+attic for more info.

  5. alison says:

    I am now very confused. My understanding is that you must have a ventilated attic for the radiant barrier to be effective. The house I’m working on is essencially a new build. So do I plug the holes or vent the roof?

  6. Lynn Ezerski says:

    What if you bought a house where the owners had a new roof put on using ridge vents. There are holes still cut out in the attic from the wood that used to have the roof vents. How do we close these off so that it is secure for someone to walk on the roof?

    • Ed says:

      The best way to close these opening off so you can walk on the roof without danger of falling in would be to use some plywood with wood framing for support.

  7. Rich says:

    Hi,
    I am confused on this topic. It sounds like the roof gets hot, radiates heat into the attic, and this does most of the heating up there. I do not have ridge vents, just two wind turbine vents in the roof and an old vent fan that really some idiot installed a long time ago that does little. So I wanted to install a radiant barrier. My trouble is that since I have to ridge vent, the air in the gap between the barrier and the roof is trapped there and stagnant, so it seems to me will just get hot and then conduction will occur through the foil. Am I wrong, or if not, how to avoid this?

  8. Bobby says:

    I have looked over and read most of the information on your site. The “hybrid” method seems to be the fit for what I have in mind. I am thinking of using two separate inlet/outlet systems for the attic. I would install the radiant barrier, as per the hybrid method, at the eave, and incorporate the flat top method with static ridge vents. This would cause the heat to rise with a vertical vortex. Secondly, after covering the gable ends with radiant barrier to completely close in the attic, I would use the gable vents for the other system. I would probably add unfaced batt insulation on top of the blown-in fiberglass. One end open and the other has a thermostatically controlled fan for the exhaust. Please comment on this arrangement. I am planning to install the radiant barrier next week. Thank you.

    • Ed Fritz says:

      Bobby,

      Wow, I think you are WAY over-thinking this. Often, there is too much emphasis on attic ventilation when installing a radiant barrier. Let me give you an example: If you park you car in the shade, does it really matter if you crack a window? Here is why. The radiant barrier rejects so much heat that usually whatever attic ventilation you’ve got is usually pretty adequate. I always recommend installing the radiant barrier FIRST. Then, put a thermometer inside the attic below the foil. If the air below the foil gets more than 15-20 degrees hotter then the outside temperature THEN increase the attic ventilation. You do not want to “seal” the AtticFoil, this is not the intention. You want air to flow freely from the bottom of the attic to the top and you want to install the radiant barrier in a way that will not impede, restrict or bottleneck the airflow. Remember, the BEST CASE lowest air temperature inside the attic is going to be the outside air temperature.

  9. Josh says:

    I have a house built in the late 70’s I am looking to add a radiant barrier to. The ventilation in the attic consists of 2 whirly birds and 2 end gable vents roughly 2×3’s? Is this enough ventilation to support a radiant barrier or do I need more? (House is rought 1700 sq ft)

    Thanks.

    • Ed Fritz says:

      Josh,
      Do you have soffit vents? Your home may have originally had a wood roof with no soffit vents. If you don’t have soffit vents, the the ideal system would be to install soffit vents to act as intake vents.

      Radiant barrier will still be beneficial even with limited ventilation. I would be sure to leave a gap at the bottom near the attic insulation. Air will naturally be drawn in the bottom and head towards the top as it heats up. Here are some install instructions: http://www.atticfoil.com/radia.....uction.htm

  10. Josh says:

    Ed,

    Thanks for the response. It confirms what I was thinking. I need to add soffit vents. How many would you recommend based on the size of my home of 1700 sq ft? I was thinking maybe 8 total. 4 on the front and 4 on the back with a large enough whole in each one to have plenty of ventilation. Of course I’d make sure to not cover the holes with insulation.

    Thanks!

    • Ed Fritz says:

      The general rule is about 1 square foot of NFA (net free area) or “hole” for every 150-300 sq. ft of attic space. If you have 1700 ft, then you would need about 5 and 11 total square feet of NFA. This is generally split between topside exhaust vents and lower intake vents either 50/50 or 40/60 with more on the lower side. If you go in the middle with 8 square ft. NFA then you would need about 4 sq. ft of of NFA for the soffit vents. At 144 sq. inches per sq. ft. this is 576 sq. inches.

      An 8″ x 16″ vent provides 56 sq. inches of NFA per vent. http://www.airvent.com/homeown.....eave.shtml Note: NFA is different from the vent size. You would think that an 8×16 vent would provide 128 sq inches, but it’s only 56 of OPEN space.

      Given all this, you are pretty close with 8 or 10 vents. 8″x16″ soffit vents will do the trick. If you arer using smaller vents 4″x16″ or 6″x16″ you will need more.

      • Laura says:

        I am in a similar situation. House built in 1935 with cypress roof, 1 gable vent and 12 little domed vents under the two other gables. Previous owner reroofed with composite shingles and resided, getting rid of the 12 little vents (I am guessing that each one was 10 sq in. – I’ve only seen photos of them.) They added 2 turtlebacks with the roof job. The square footage of the house is 1070. What if soffit vents aren’t an option?

        There is a covered porch and the attic space of that opens into the main attic. Could soffit vents be put in the ceiling of the porch? It would be the lower part of the attic space?
        We are also looking at replacing the 2 8inch turtlebacks with 2 turbines.

        • Ed Fritz says:

          Laura,
          Yes, you can put intake vents under a covered porch area. You can use soffit vents or a better option is to use off-the-shelf air conditioning grills in just about any size.

  11. John Scott says:

    I have about 2,600 square feet in my home. I currently have 2 power vents near the top of my roof line. I have 30 (8 X 16) soffit vents around the house. Yes, after two repaintings I am sure that those vents are somewhat restricted with paint, dirt, etc. I have bought 30 new vent covers to replace those old covers. We do need to repaint and/or install vinyl siding on those soffits. I will install the new vent covers if we repaint. However, if we go with the vinyl on those soffits I have noticed that the vinyl covering for the vents are only 12 inches wide with fairly small vent holes. Those would be placed over the current holes cut for the soffit vents. QUESTION: Would I still get adequate venting with the vinyl coverings over those soffit holes with those two power vent fans? I am probably over-powered with the power vents and I do not want to have too little venting from those soffit vents so as to cause the air conditioning to be pulled from inside my home into the hot attic. Your advise PLEASE!

    • Ed Fritz says:

      John,

      With vinyl siding, you can just take a circular saw and cut out a bunch of rectangles in the soffit before you install the vinyl siding. You are correct, the vinyl siding that has holes is a little lacking in open area, so you want to install a lot of it. Another option is to replace the existing soffit with a hardy board type soffit that has continuous vent holes. Finally, you can cut a hole in a porch and install an air conditioning vent grill and paint to match. It will act as several soffit vents. It’s easy and rain won’t be able to get up and inside.

  12. Josh says:

    Thanks again Ed for such valuable information. I see another project to add to my growing list!

  13. Rick says:

    I prefer large passive domes to whirlybirds or slantbacks. Whirlybirds have no screening against critters and wasps, and slantbacks are too small for effective ventilation even though they are very weather resistant.
    My next project is radiant barrier up there.

  14. Robin says:

    Ed,

    My attic is about 2500 sq ft. It has adequate soffit vents (2004 construction south of Houston). My plan is to install radiant barrier along the rafters and to install two solar fans (each 25-watt, 1600 CFM advertised) in the attic near the top of the roof a few feet from each other. Currently there is one non-functional electric fan in the attic near the top of the roof. Any objections, is this overkill? Any recommendations on a solar fan manufacturer?

  15. Ed Fritz says:

    Robin,

    I’m OK with solar fans as long as the soffit vents are clear and open. The fact that you have a non-functional electric attic fan is probably due to the soffit vents getting too dirty. This limits air into the attic and cause a drag on the motor which eventually burns it out.

    Clean the soffit vents with a wire brush and I would even pull out some of the wire mesh to allow air to flow freely.

    Personally, I would go with 2 or 3 14″ wind turbines. They work 24/7, in the dark, and are cheap compared to solar fans. Plus, with a typical 8 mph wind, they will pull a similar amount of air as the solar fan. Plus, once you install a radiant barrier, so much heat is kept OUT of the attic, ventilation is not as critical. Just like if you park your car in the shade it does not really matter if you crack your windows. 3200 CFM with radiant barrier IS overkill.

  16. Tom says:

    Hi Ed,
    I have about 2000+sqft attic space which my home inspector said doesn’t have enough soffit vents. I also have about 6 passive air vent near the roof ridge. I was planning to put more soffit vents and a 1250CFM solar fan. But reading your article, if I simply install one solar fan and leave the other 5 passive vents unchanged, that may simply pull air from outside and cylce it back again through the solar fan? So should I close off some of the passive vents? Do they have some mechanism to keep the air from flowing back in from the outside but still allow air flow from inside to outside?

    The other option am considering is to relplace the passive vents with two or three wind tubines.

    What would you recommend?

    • Ed Fritz says:

      Keep it simple.

      I’d go with two or three 14″ wind turbines. What many people don’t realize is that two 14″ wind turbines pull as much air as an electric or solar fan with an average 8 mph wind – which is pretty typical. This is pretty impressive. If you don’t think it’s windy, stand on your roof and you’ll be surprised. Plus, they work 24/7 pulling heat and moisture out. They don’t quit when the sun goes down.

      For the remaining static vents, just staple something (cardboard, roofing felt, etc.) inside the attic to choke down the airflow. You don’t need to SEAL it airtight, just cause air to be drawn in from the soffit vents.

  17. Jerry says:

    Hi Ed,

    When I built my house, I asked the roofers to install three electric attic fans in my roof. I forgot to tell them to NOT install the several (what I call) static, or passive vents in the roof, that is, those small, square vents that you see near the top of so many roofs in North Texas. It sounds like having both types of vents is a bad idea. What should I do? Should I simply turn off the electic attic fans? Should I plug the passive vents? Something else?

    Thanks.

    • Ed Fritz says:

      Jerry,

      It depends. Three attic fans for most homes is probably TOO much ventilation. Having THREE fans pulling air OUT of the attic is OK only if you have plenty of places for air to come INTO the attic. So, if you have plenty of soffit vents to “feed” the fans (just clean them every year or two or the motors will burn out) then you would probably be OK blocking the static vents. I’d measure the air temperature. With this much potential air movement, the AIR temperature should only be a few degrees above ambient temperature. I’d turn the one fan off and see if it change much and then decide if the 2nd or 3rd fan is really doing much. Remember your attic temperature will never be cooler than the outside air.

      Do you have a radiant barrier? Are you planning on installing one? If you install a radiant barrier, it will drop the SURFACE temperatures inside the attic compared to the air temperature in the attic. This is really what drives heat flow – the top SURFACE temperature of the insulation. It can easily be 120º or more even if the AIR temperature is only 100º. This is like leather seats heating up in a car with the windows rolled down – great ventilation, but you still have HOT seats.

      Most customers find that after installing a radiant barrier whatever attic ventilation they have is usually adequate. If you can keep the heat OUT, then you don’t really have to manage it. Using the car analogy, if you park you car in the shade, then it really does not matter whether or not you crack the windows.

      Hopes this helps! Visit or call us for more info http://www.AtticFoil.com

  18. Hank Fisher says:

    Hi,
    Have recently had all new plywood, a metal roof put on my house and radiant barrior also. Have attic vent fans at each end of the long roof. What temp should the attic fans be set at?—Central Florida location

    Thanks,

    Hank Fisher

    • Ed says:

      The temperature at which an attic fan ought to be set differs, depending on climate. However, the average accepted optimal setting is about 110 degrees Fahrenheit.

      • Hank Fisher says:

        Thanks much.

        Before your note, I had set them to 120 because they seem to be starting up at 110. The temp here is 70-82 The problem may be the long attic 85ft long an about 50 wide. Lots of space under this metal roof. Attic fans at each end. Soffit feeds new an run both sides along the length.

  19. DH says:

    Great questions and answers!

    My house was built in 1952. There are no vents except for four triangular shaped gable vents right below the ridge line. The house is T-shaped, 2000 square feet. Each gable vent is allows approximately 100 sq in of venting. There is also a ridge vent along the long axis of the “T”. The attic insulation is blown in rock wool, and not very much of it. My plan was to add an attic fan at one end and increase the venting at the opposite end by 200 sq in. The fan mfr advised to block the ridge vent since this would defeat purpose of the exhaust fan. I’m impressed with the possibilities of radiant barriers and would like to use both systems….but my mind is wide open. Would really like to avoid drilling/cutting a whole bunch of soffit vents.

    • Ed Fritz says:

      I would not do ANYTHING until the radiant barrier is installed. What most customers find is that after they install AtticFoil® Radiant Barrier Foil the attic is so much cooler they don’t need to adjust the ventilation. Radiant Barrier REJECTS heat from ever entering the attic. Therefore, since less heat is coming in, ventilation becomes less critical. This is like parking your car in the shade. If you park in the shade, you really don’t need to crack the windows right?

      Just leave a few inch gap along the ridge when installing the AtticFoil®. Then AFTER it’s complete measure the AIR temperature inside the attic below the foil. Ideally, it will be less then 15 degrees hotter than the outside air temperature. IF it’s hotter, then you need to increase air flow. Based on experiences of thousands of customers, I think what ventilation you have will probably be adequate.

  20. Sean says:

    Hi,

    I have 2 wind turbine vents ~2/3 up the roof and plenty of soffit vents, but no ridge vents.

    I understand that with radiant barrier I need to leave open space round the turbines, but won’t the heat just pool at the top of the attic (hot air up, cool air down) since there is no way for it to get out?

    • Ed Fritz says:

      Sean,

      Think of your attic like a drain in the bathtub. Yes, Ideally the the top hole in the attic would be at the absolute highest point – ridge vents. However, the wind turbines will “skim” the air out of the top of the attic. It’s no big deal if the air above the wind turbines is a little hotter. It not enough to even notice. The most important thing is we want the air down low in the attic to be as cool as possible. This will keep your insulation, ductwork and framing the coolest.

      Just leave a gap along the ridge and give the air a path to always find its way to the top. The wind turbines will work great. You should install the AtticFoil® Radiant Barrier in a way that does not change/modify the airflow in the attic one bit. The air should continue to flow through the attic as though the foil is not even there.

      • John says:

        Hello Ed,
        I have a 1981 NJ ranch house with a 45’x35′, 1,540 sq ft attic, with R-30 paper faced (down) fiberglass insulation. The intake soffit vents are the non-continuous double, pre-stamped aluminum type, alternating with solid soffits, and are fortunately in line with the WEST to EAST air flow that exits out a mesh ridge vent added with the new roof shingles. There is also one gable vent each on the NORTH and SOUTH side of the house.

        I intend to install your radiant barrier on top of the attic floor insulation, and also on the hot, SOUTH side gable wall. My question: Are these GABLE VENTS REDUCING the draw/draft efficiency of the intake soffit/ridge exit vents’ airflow, and if so, should I seal them closed?

        Thanks, John

        • Ed Fritz says:

          John,

          This can be a little tricky since all ridge vents are not created equal. In theory, yes you would block the gable vents and use a soffit/ridge system alone. However, this is assuming you have ridge vents that are clear/open and have a fairly high NFA (net free area). These ridge vents are usually the taller “baffled” type and not any low profile or “invisible” ridge vent – which often provide almost NO ventilation.

          I would something like roofing felt and staple up to block the gable vents. It does not have to be airtight. You are just trying to choke down airflow from the gables. Then, see what happens. If the air temperature is good, then do nothing. IF the air temperature goes up, then I’d tear down the felt and use combination of the ridge and gable vents. In this case the gables are actually the main vent assuming the ridge vents are limiting airflow.

          Finally, if you are installing OVER the attic floor insulation and ONLY have batts, then I would top off the insulation with blown-in insulation before installing AtticFoil® Radiant Barrier Foil. The most critical part of attic insulation is the few inches ABOVE the ceiling joists. By covering them, this will greatly reduce “Thermal Bypass” where heat will actually go around the batts by conducting through the wood.

  21. kent beuchert says:

    One of the really stupid HVAC designs used here in Florida is
    to run flexible ductwork thru the attic furnace. Mine reaches 135 degrees and results in duct air temp increases approaching 8 degrees from my heat pump exchange unit to my bedroom vents.
    When the attic temps are 85 degrees or less, there is no heat gain of the air travelling thru the ducts. Therefore, while I
    can understand the value of reflecting radiant heat to reduce the heat transfer thru the blown in insulation in the attic, I think perhaps just as important is to reduce the attic temps so that the ductwork can convey the cool air to the outlets without excess heat gain in the process. Where can I find that information on the atticfoil.com website?

  22. EJ says:

    The room above my garage is surrounded by attic crawl space and gets hot, i mean hot! There are soffit vents around the perimeter, no ridge vents, and a passive gable vent. I have started to install the radiant barrier and added an electric fan to the gable vent.

    1. I have completely sealed off the attic with foil. I assume now i need to go back and open it up a bit to correct the airflow from the soffits in to the crawl space.

    2. Is there anything to gain by adding a second radiant barrier over the insulation in the room walls?

    I guess i felt i needed to trap the heat from entering, but after reading your blog it appears i don’t need to trap the heat, but rather let it flow and reflect what heat i can with the radiant barrier.

    • Ed Fritz says:

      EJ,

      Yes, you want to “open up” the foil to allow air to flow freely through the attic. Basically, air should flow through the attic as though the AtticFoil® is not even installed. I would check the soffit vents to make sure they are clean and free.

      You are correct, we want to reflect the radiant heat and use air to help pull heat out of the attic and to provide a cooling effect for the roof.

      I would not double up a radiant barrier. One layer should do for most applications.

  23. James says:

    I have about a 3,000 square ft. attic and just installed 8 additional soffit vents on each side of the house. This brings my total up to about 26 vents. I haven’t installed radiant barrier yet. This is the first I’ve read about ventilation not being important. Everyone I talk to says you need good ventilation. Before this weekend I only had 10 vents and my attic was already reaching 150 dregrees. Now that I have this much ventilation should I skip the radiant barrier and just blow in insulation? Since I did it myself I spent nearly as much on equipment/tools for soffit vents as I would for all the radiant barrier I need.

    Thanks for all of the information.

    • Ed Fritz says:

      Ventilation is nice, but it can only do so much. Think of your attic like your car parked in the sun. You want to keep the leather seats cool. You can open the window and have great ventilation and the actual air inside the car will be about ambient. However, if the sun (radiant heat) hits the leather they will STILL be very hot. Same thing with an attic. The top SURFACE TEMPERATURE (measured with an infrared thermometer) can typically be over 120º even if the actual air temperature is much lower. A Radiant Barrier will keep the top SURFACE TEMPERATURE DOWN. Think of “regular” insulation as an ice chest and radiant barrier is like putting the ice chest in the shade. You actually need both for best results.

      150º degrees seems REALLY hot (for the air). Is this the AIR temperature or are you using an IR thermometer and measuring something with mass inside the attic (bottom of deck/supports etc.) ? Feel free to call me at 800-595-8772. Ed

  24. James says:

    Ed – Thanks for the info. It was done with an IR thermometer on various surfaces. I’m going to get a basic remote thermometer to put in the attic pretty soon.

    • Ed Fritz says:

      In that case, 150º is no big deal. Typically, on a hot-sunny day the tops of the shingles will be over 170º and the roof deck below the shingles can easily be over 150º. Here is a thought to ponder? How does stuff 10-20 ft AWAY from the roof reach temperatures of near 150º…..yet the AIR inside the attic is much cooler? Yes, radiant heat transfer. Heat transfer by NON-CONTACT! Radiant heat transfer is an incredibly efficient method of heat transfer. However, we can also use this to our advantage. Since the heat MUST transfer to a wave-form to cross the air space we can literally direct it (radiant barrier) anywhere we want to. Heat flowing through a solid (by conduction) can ONLY be SLOWED down. Think of an oven mitt. You can pick up a hot pan for a while, but eventually the heat will make it through and it will feel hot.

  25. […] finishes up his interview by explaining surface temperatures, roof temperatures and the importance of attic ventilation to get the best results and the most comfortable living space.  He also explains why predicting […]

  26. David says:

    Ed,

    You are doing a bang up job with the blog and I hope it is paying off. I know it has paid off for me as a consumer. Your approach is exemplary.

    I had an attic installed 4 years ago and the roofer took two brand new vent fans and changed the system to a ridge vent system. Well, to make a long story short, the roofer never opened the ridge vents to the attic space. I just had this repaired and the metal (not low profile) vents replaced the plastic ones that also did not fit well. I took a drywall knife and opened every soffit vent opening that had been covered with paint. I then purchased a mini rake and made sure the bat and blown insulation was not covering the soffits from inside the attic. This has all helped but not enough to help with the upstairs heat issue in the hot Georgia sun.

    So thank you for your informative information you provide on this site. I’m now going to make sure my knee walls are flashed. I’m also going to install a radiant barrier system.

    It is amazing how I have never heard of this from any of the roofers or AC guys over the years. This internet rocks cause now I know. I also love your hot car in sun example.

    Now off to http://www.atticfoil.com.

    Thanks ED!!!!!!

  27. sanjay says:

    I have soffit vents but do not have ridge vents. Instead I have 2 gable vents and also 2 vents in the roof about 1/3 from the top.
    I want to install radiant barrier. If I install it on the rafters all the way to the top then the air in the top 1/3 of the roof under the radiant barrier will have no way to escape. It seems to me that radiant barrier on the roof rafters will not work unless one has ridge vents.

    What is my solution. Can I guess I can install radiant barrier on the two thirds part below the roof vents but not sure if it will be good enough. The other possibility is to install it on top on insulation on the floor and perhaps add another batting on insulation on the top of the radiant barrier. This would stop the heat from getting into the house.

    • Ed Fritz says:

      Don’t over-think this. Hot air will flow like water up to the highest point. Just follow the Radiant Barrier Staple Up Instructions and leave a gap at the top along the ridge. Air will flow towards the top and find it’s way out. It may not be EXACTLY at the highest point like with ridge vent, but don’t worry about it. Radiant barrier will work WITHOUT ANY airflow. It just works better WITH airflow. The air gets hot by extracting some of the heat off the roof. It’s basically a cooling mechanism and good airflow will keep the roof a LITTLE cooler – not much though. The main reason you want the hot air to get out is so it does not “backup” or get “plugged” and cause ductwork to be immersed in hot air.

      • James says:

        Ed, I am in a similar situation as Sanjay. I have a 1500sqft house in North Florida. It has a hip roof and vinyl soffit all away around the house. It only has 3 4 foot passive vents about a yard away from the roof ridge. This seems way under vented to me. How much of a benefit would it be to convert to ridge vents and close the 3 foot vents if I installed attic foil to the underside of the rafters leaving the proper top and bottom gap?

        • Ed Fritz says:

          James,

          You can vent all day long and it won’t really drop surface temperatures in an attic. This is like blowing a fan on my sunny driveway – it does not do much. I always recommend installing radiant barrier FIRST and then if the actual air temperature inside the attic is still hot, then start cutting holes for air to flow in the bottom and out the top. Remember, the LOWEST the air temperature can usually get is the ambient (outside) temperature. No matter what most attics (even with radiant barrier) will be a little warmer than outside.

  28. David says:

    Ed,

    Your website instructions are excellent as well as your product.I wanted to know what your opinion of the Aura vents are ( no moving parts just a vortex by air moving from bottom soffits up to vents)?
    Are they as good as whirlybirds or does it matter?

    Also I am installing radiant barrier in a 6000 sq. ft. attic with a cathederal ceiling 15 ft high on center about 100 feet in length. I have enough soffit ventilation, how many roof vents at the top would I need for adequate ventilation, if needed (it has a ridge vent partially blocked)?
    Thank you, Ed

    • Ed Fritz says:

      David,

      What you will find is that after installing a radiant barrier, you don’t need as much ventilation. I would install the AtticFoil® Radiant Barrier and then measure the ACTUAL air temperature below the foil. If the air temperature STILL tops out over 15º-20º above ambient, then start cutting holes in the top of the attic assuming you have plenty of soffit vents as stated. Personally, I like ridge vents or wind turbines. I don’t have any experience with the Aura Vents. I’d like to see some actual 3rd party lab testing measuring actual airflow in CFM.

  29. Leo Nicholson says:

    We have a 1 1/2 story home, 2100 sqft down, 1300 sqft up in south Mississippi. Has spray-in cellulois walls and 14″ blown in cellulois attic. Ductwork is in the attic. Has approx 90 7″x1.5″ styrofoam channels from contineous perforated vinyl soffit and 2 large porches with perforated vinyl soffit ceilings. Has radiant barrier sheeting on roof and ends of attic.

    The builder installed ridge vents over sheeting without cutouts.

    I am considering 3 14″ Whirlybird vents. Is this a good brand to use?

    I installed a remote themometer and have the follow readings:

    Outside Attic
    07:00:00 AM 78.6 75.2 -3.4 Overcast
    08:12:00 AM 80.2 76.1 -4.1 Overcast
    09:12:00 AM 82.2 75.9 -6.3 Overcast
    10:18:00 AM 84.0 82.6 -1.4 Overcast
    11:21:00 AM 85.1 87.3 2.2 Overcast
    01:30:00 PM 88.2 96.1 7.9 Sunny
    02:36:00 PM 90.1 102.9 12.8 Sunny
    03:37:00 PM 90.5 105.6 15.1 Sunny
    04:32:00 PM 91.2 106.3 15.1 Sunny
    05:35:00 PM 90.5 106.2 15.7 Sunny
    06:30:00 PM 89.2 101.8 12.6 Sunny
    07:30:00 PM 87.8 94.1 6.3 Sundown
    08:20:00 PM 86.0 86.9 .9

    Should 3 14″ wind turbines be sufficient?

    • Ed Fritz says:

      Let me be clear. You have a path from the soffit to the ridge vent, but the ridge vent is not cut open? If this is true, then YES, I would say that 3 x 14″ wind turbines (Whirlybird Brand is good) would do fine assuming that after you cut in the wind turbines you STILL have a path for air to flow from the soffits up and out of the wind turbines. Can you send me some pictures? Go to the contact page at http://www.AtticFoil.com and attach some pictures.

  30. James says:

    Hi Ed,
    Amazing website. Actually will be picking up some radiant barrier thanks to the info from this website.

    Question about my ventilation: I live in San Diego. Most of the year we have very temperate climate and arid. So many of the posts here dont really apply (4 seasons).
    I have a 1947 stucco bungalow with composite tile roof. 1k sq feet with 2 gable vents across from each other, a turbine and a small roof vent above the living room side (house is L shaped with bedrooms and bath on longer side of L shape and living room and kitchen on the smaller part of the L).

    I dont see any soffit vents. The air seems somewhat stale and I have been opening the hallway attic door entrance to let in fresh air (ceiling).
    The previous owner decided to install a solar powered ventilator from Costco and had installed it on one side of the house. While its blowing hot air out I am wondering if I am short circuiting the air flow since there already is a turbine already installed. I would say the the turbine is placed directly in the middle of the house with the ventilator approx 15 ft away. This morning I actually duct taped the passive vent above the living room because I was afraid the ventilator was pulling in hot air from that vent (they are about 13 feet from each other).

    The attic is insulated and it seems the other gable vent is pulling in cool outside air, but not really bringing in fresh air throughout.
    I am just trying to figure out what to expect temperature wise in the house. The mornings here can be ~65 degrees outside with the interior being about the same. But gradually as it warms up throughout the day, the interior of the house will reach 80 degrees and the outside going above that to 85-90.. I have dual pane low e glass, so I am pretty sure its not the solar heat coming through as I close the blinds etc.

    So far the two HVAC companies I have talked have only tried to sell me more powerful ventilators or upgrade my HVAC system haha. Besides buying the radiant barrier (which I think will make a tremendous differnece) is there anything else I should expect or tips to do based on the info above?
    Thanks!

    • Ed Fritz says:

      James,

      You have a mixed bag of attic ventilation. Ideally, you would have soffit vents to allow air in the bottom. The air would naturally heat up and flow towards the top of the attic. Your system is moving some air, but it is difficult to really determine what to expect as far as air temperature. The problem is that attic ventilation can only do so much. Think of a car. You can roll the windows down and get GREAT airflow, but if it is sitting in the sun, the car will still FEEL hot.

      I would install the AtticFoil® Radiant Barrier before you do anything else with the ventilation. Most customers find that once the radiant barrier is installed, whatever ventilation they have is usually adequate.

      • James says:

        Ed,

        Thanks to your great website, I ordered radiant barrier and installed on the attic floor over the past few days.
        The change in temperature is dramatically lower up there now. When I used to touch the beams, they would be quite warm to the touch.
        The solar fan has a thermostat that is supposed to kick on when it hits 85 up there and it hasnt moved and current temps outside are 96 degrees.

        Amazing stuff and info. Thanks!

  31. Keith says:

    hello, i have a north texas, dallas suburb home built in 1953, 2200 sq ft, was originally cedar shingles, has 2 gable vents and i have installed 2 whirly birds, am thinking i need additional blown in insulation and to install approximately 16 soffit vents (do they need some thing in the attic to keep them clear?) and is that enough for the exhaust or even block the gable vents off?

    • Ed Fritz says:

      Keith,

      You biggest impact item will be to install soffit vents. Old wood shingles were naturally vented. Once you deck and close up an attic, you need holes in the BOTTOM and the TOP to allow for airflow. I would install the soffit vents and then decide whether or not to block the gable vents. Have you considered installing a radiant barrier? http://www.AtticFoil.com

      Combining, good ventilation, radiant barrier, and insulation are 3 of the 4 silver bullets I talk about in this article. http://www.radiantbarrierguru......-climates/

  32. kenny says:

    hello, i live on indiana ,michigan border. i’m getting ready to reroof, and add more insulation, and a radiant barrier. i have 22″ sollid alluminum soffits[non vented] and only 3 box vents on roof. am thinking of perforated soffits. should i replace all soofits with perforated and install a ridge vent and close off box vents. house and garage are 1500 sq. ft. Also, living up here, is it better to install the radiant barrier on top of the blown in insulation. i have no moisture barrier now, just shredded fiberglass insulation, about 8-10 inches deep. thankyou for your knowledge and help.

    • Ed says:

      Most customers opt for a passive ventilation system which is just a combination of working (ie. clean, unobstructed) soffit vents and either a ridge vent or a pair of gable vents; oftentimes nothing more is necessary. Once a radiant barrier is installed, your attic air temperature should be within 10 degrees of outside air temperature. If it’s not, then more ventilation is probably necessary.

  33. Craig says:

    I have two story Dallas home built in the 90’s with fairly large simple gabled roof. Blown insulation on the attic floor. Limited soffit vents. Two passive (looks like opaque plastic) vent domes near top roof line. Questins:
    1. Radiant barrier: Foil or spray paint?
    2. Do I add insulation to attic walls under gables?
    3. Is foam an option or is just for use in what I would call an unconditioned attic room that has HVAC equipment?
    Thanks!

    • Ed Fritz says:

      Craig,

      1) I would go with foil over paint. Not just because I sell foil http://www.AtticFoil.com , but it really is better and more effective. Did you read my post on Radiant Barrier Foil vs. Paint?
      2) No need to insulate walls below gable vents. They are usually not part of the “Thermal envelope” – Just part of the roof in a vertical format. Walls in the attic that have living space on one side and attic on the other NEED good insulation. We call these “hot walls” for a reason.
      3) Foam is an option, but unless you convert to a “sealed” or “conditioned” attic, foil is probably your best bet. I love foam for new construction, but it can get tricky on existing homes. One problem is that you can reduce the heat load SO much, that your air conditioner becomes too oversized and you run into moisture / dehumidification problems.

  34. Don says:

    Hi, Ed. Can’t even describe how much respect I have for your data and the way you present it on your site. You’re a natural-born teacher. Here in cold Connecticut, a properly functioning attic system is vital, but so few people give it proper consideration. Recently did a new roof, added ridge vent across the peak, with high-NFA (Certainteed) soffit venting all around the perimeter. This is a dutch, and the gambrel poses some air-flow issues, although I have air flowing in and above the gambrel break in the attic framing. That said, I’m concerned that I’m getting resistance from the local building inspector when I suggested that I’m going to place your radiant barrier to my attic rafters. I think your barrier would help reduce the heat generated from, and transmitted by, my roof deck, which faces west and is a rather large gambrel surface. [One other complication…long before I knew to add soffits and ridge, we added a power attic fan through the roof, which cools down the attic, but I now have a mixture of exhaust vents. What do you, as the expert, recommend? I’m still committed to your radiant barrier as a proper next step. Don

    • Ed Fritz says:

      Don, Thanks for the kind words. What kind of resistance are you getting from the inspector? I don’t see any issue with your plan. As for the mixture of ridge vent AND Electric fan, just set the fan for about 120º. Normally, the soffits and the ridge vents should do the trick. IF it gets over 120º then the fan will kick on and should help pull down the temperature. What you will find is that after the AtticFoil is installed the attic is so much cooler, usually whatever ventilation you have is adequate. My guess is that the fan will rarely turn on.

  35. Erin says:

    I am trying to insulate my cape style home built int he 50’s. The second story is finished with knee walls inside. On the back side of the knee walls within the attic space are the heating lines. I live in Vermont with very cold winters. I am getting a lot of icicles. In the upper attic flat space there is insulation batts rolled out. I currently have proper vent on the slanted roof line with fiberglass over the proper vents behind the knee wall but it does not reach as high as it should past the flat attic space. We are looking to fix the problem and I was wondering if I could foam the slanted roof line up to the height of the knee wall and then use blown in cellulose for the flat attic space. If this is some thing we do do I need proper vent behind the foam to allow for air ventilation up into the flat upper attic space? Or any other suggestions to solve the problem of icicles??

    • Ed says:

      A radiant barrier will usually REDUCE the possibility of ice damming. Ice damming/icicle formation is caused when the top of the roof warms above the freezing point and the lower part of the roof is below freezing. To prevent ice damming, you want a COLD roof; right now the roof gets warm due to warm air leakage into the attic from the house AND from the home emitting radiant heat.
      A radiant barrier installed on the floor over the insulation will help keep the radiant heat emitting from the home from hitting the roof; additionally you should wrap the attic side of the knee walls as well since they share space with a heated room and can emit heat. The result is a COLDER roof deck, which will reduce ice damming. Many customers have seen a significant reduction in ice damming after installing radiant barrier. I would also suggest inspecting your ventilation to make sure you have good intake vents, since cold air entering the attic will also help keep the roof COLD.

  36. Cher says:

    Living in Texas with our extreme weather causes me to ask what should I request when getting my roof replaced due to a hail storm.
    Our summer of 100 plus temperature for 70 days this summer and ice storms in February cause my confusion. My roofer wants to put in ridge vents and 2 turbines for my 2 story 2,000 square foot home.
    I already have the soffit air vents and I painted the interior side of the roof in 2000 with radiant barrier paint (since I painted it with a roller I couldn’t get to all areas). The house was built in the mid 90s. Do I need the turbines, will they help? My 2 air-conditioning units are in the attic as well as my tankless water heater.
    The roofer plans to put the ridge vents on different levels since I have a multi-gabled roof and the vents would be at different levels which I believe you said would be overkill. Thank you for your comments.

    • Ed says:

      As far as ventilation, I’ve done hundreds of homes. If you install the foil inside the attic decent ventilation is sufficient most of the time. I think passive is all most people need (with a few exceptions). Installing a radiant barrier is like parking your car in the shade, it really does not matter if you crack your windows (ventilation) or not.

  37. Keith says:

    GOOD INFORMATION! I have a 2600 sq. ft. home with ridge vents. I was actually going to install those solar powered fan type vents up towards the peak above the ridge vents. But now, reading this article, I know that is a NO NO! Will stick with the soffit/ridge vent system. Has worked for a long time. Thanks for the information ED!!!!!

  38. Elmer McCann says:

    I live in the Midwest and just had my roof reshingled after hail damage. My contractor suggested replacing the turtle vents (10) with ridge vents. This required ridge vents on the downslope ridges as well as the peak ridge. Is this a good way to vent the attic? My home is 1450 sq ft. and 18 yrs old. The attic is cathedral high. There are plenty of soffit vents.

    • Ed says:

      Most people opt for a passive ventilation system which is just a combination of working (ie. clean, unobstructed) soffit vents and either a ridge vent or a pair of gable vents; oftentimes nothing more is necessary. Ideally the best case scenario is one in which you have a radiant barrier installed and your attic air temperature measures within 10 degrees of outside air temperature, if not the same as ambient temperature. If it measures higher than that, then more ventilation is probably necessary.

  39. Kyle says:

    Our house has a main attic above the second floor, but two lower inaccessible attics over the outside rooms on the first floor. The side attics don’t really attach to the main attic except for one duct chase on one side. The side attics don’t have any upper exhaust vents. Would you suggest adding some passive air hawk type vents near the top of these? They have soffit vents on them, but no idea how clogged they may be. Thanks for all of the great information.

    • Ed Fritz says:

      Kyle, Yes attic ventilation must have holes in the bottom and holes in the top for air to flow in and out. If you have separate “cavities” then I would consider adding some passive vents (air hawks) for this area – especially if the area around the duct is small or far away from the main parts of the lower attics. Before I do this, I would focus on the soffit vents. You should be able to feel the difference in how much air is flowing through the duct chase by cleaning/opening/adding more soffit vents. If you can get good airflow through the duct chase (even if it’s a little small) then you be able to “flush” air through the lower attics without adding more passive vents.

  40. Paul M says:

    I have a house with vaulted ceilings (Mainly North). The ceilings flatten out up toward the peak. There are roof vents on top of the roof towards the peak, but there isn’t one soffit vent for the whole house. Is there a good way to know if it is a safe to add soffit vents? There is a part of the house that doesn’t have vaulted ceilings (south side). Would I be able to add enough soffit vents in those areas to adequately move air thru the entire attic (North and South)?

    • Ed says:

      Paul,

      I’d recommend you contact a roofer to take a look at the situation. The most important part of attic ventilation (in my opinion) are the intake (soffit) vents. Typically the venting is sufficient if, in combination with a radiant barrier, the attic air temperature reads within 10 degrees of ambient temperature. Have you measured the air temp up there? See where you are at and then I’d recommend contacting a contractor to see about getting some soffit vents installed.

  41. clayton says:

    I have an old home aproaching a 100 years old very sturdy with a full attic, my ultimate goal is to turn the attic into useable space currently there is no ventalation other then windows when they are open. do i need to add ventalation before i tackle insulating and drywall?

    • Ed says:

      If you are going to condition (heat and/or cool) this space, then you need to make sure it is sealed up and airtight. This would be the first thing you want to do. Once it is sealed air tight you can install the foil via the Cathedral Ceiling Method.
      Otherwise, if you don’t plan on heating/cooling the space, then you can just install the foil behind the drywall layer with an air gap.

  42. Melissa says:

    Not sure what is best? I live in Michigan and own a 1950’s bungalow home. I am getting different quotes on roofs right now. I currently have a ridge vent on the home with ~4 canister vents. Both companies have suggested to cover the ridge vent. However one company suggested to install “smart” soffit vents and the other suggested to keep gable vents and more canister vents. I don’t beleive there is enough overhang of the roof to install regular soffit vents. What is best?

    • Ed says:

      Attic ventilation is VERY simple. You have HOLES in the bottom of your attic (usually soffit vents) and HOLES in the top of your attic (ridge vent, wind turbines, static vents OR power fans). Ideally, air comes IN the bottom and OUT the top. It’s just like a chimney in your home. Pretty simple: holes in bottom, holes in top… without seeing your space, I can’t make a fair evaluation, but I’d go with your gut. Remember, the best price isn’t always the best service or the best solution. You’re on the right track with asking several companies what their solution would be, but don’t let it get over complicated. With enough air flow going through an attic space you can feasibly get that temperature to drop to close to ambient (outside air) temperature.

  43. Susan says:

    I have been given estimates for radiant barrier and spray foam. The spray foam people say that radiant barrier would be more costly since I need a roof ridge and my soffit vents are covered with insulation. The radiant barrier people didn’t say anything about this. Because of the cost, I was thinking of buying the radiant barrier and doing it myself. But do I need a roof ridge. I have two attic fans. Believe only one is working and I guess I could uncover my soffit vents myself by moving the insulation.

    What do you think. Any suggestions.

    • Ed says:

      While proper ventilation (intake at the soffit level and outtake near the peak of the roof) is recommended, it is not required for the product to work. Ventilation helps address the air temperature and promotes drying out of moisture and while though those two things are important, they are not related to the effectiveness of the radiant barrier blocking heat. Regardless of your ventilation, the foil will still work to block 97% of radiant heat attempting to enter the home as long as when you install it there is an air gap on at least one side of the foil. That being said, I DO recommend you clear out those soffit vents so they can bring air into the attic space to promote air flow.

  44. Daniel says:

    I live in a 2 story house in Midlothian, Texas. I am currently trying to decide what all I should do with my attic to reduce the heat. We have soffit vents that go around the house and 99% of them are clean. There are about 6 static vents. It is currently dark outside, so I am not sure if I have ridge vents.

    What is your suggestion?

    I am considering solar attic fans or radiant barrier or both if needed.

    • Ed Fritz says:

      Daniel,

      The number one thing you can do to reduce heat in the attic is to install a radiant barrier. Most customers find that whatever attic ventilation they have is usually adequate after they install a radiant barrier. The way you check is to measure the air temperature AFTER installing a radiant barrier. If the air temperature below the foil is MORE than about 10-15 degrees above ambient (outside) temperature then you need MORE airflow through the attic. Basically, the attic is CLOGGED and the air is getting STUCK in the attic. At that point, I would choose ONE type of exhaust method and combine it with clear and open soffit vents and you will get the air temp inside the attic down to close to ambient. Call me if you need more help/info.

  45. Brian says:

    I have to re-roof my house because the shingles are curling, and baking. Before i put a new roof on, i need to fix the ventilation problem, that has caused the problem.I currently have 2 attic vents, and 2 turbines on the roof. The house is a cape cod style with no overhang, and no soffit vents, so how do i ventilate the lower part, or get proper intake air. It was recommended that i put a ridge vent on the top, but not sure what to do about the intake air in the lower part of the attic, I would appreciate any suggestions, Thank You.

  46. Thom Westergren says:

    Thanks for the great service you are providing.

    I have to disagree (somewhat) with this idea of short-circuiting. Hip roofs can be difficult to vent, as your example shows. A second type of vent is not going to suddenly stop all air movement.

    Sure, when it comes to wind, you will get air going in one vent and out the other. This can even happen with vents that are side by side as well as un-baffled ridge vents (almost all that’s being used these days) which allow the wind to simply go in one side and out the other. However, the majority of the time the air movement is from thermal differences within the space, not wind.

    Like you say yourself, “Holes at the top, holes at the bottom.”
    Rising of heated air will move the air out. One vent of a different type or down from the ridge a bit is NOT going to suddenly stop the thermal movement.

    I need to do something with my hip roof because it now has half the ventilation that it needs (from everything I read out there). And there is no place to put more on the side that is now vented, so additional ridge vent seems to be in order.

    Perhaps you could elaborate or show some “over thinking” resource that explains it better? At least you did use the word “probably” so, it must not be as black and white as all that, right? What would you have done on the house shown, or something similar?

    • Ed Fritz says:

      Thom,

      Thanks for the comment. Short-circuiting is usually not a big problem if you mix different types of PASSIVE vents. Example: combining wind turbines and ridge vent will still be somewhat effective. The BIG problem is when you mix a POWERED fan and passive vents. If you put a powered fan next to any passive vent, it will have a significant short-circuit effect. The air in the lower part of the attic will barely move and you won’t get the airflow along the bottom of the roof deck to provide a cooling effect. Combine this with clogged or dirty soffit vents and the air will be practically still in the bottom of the attic and whipping through in the top couple of feet.

      Ridge vent is usually never a good solution for hip style roofs. There is just not enough RIDGE to provide enough open area. I would go multiple wind turbines, turtle vents or ONE fan and block off the other exhaust holes. On the house shown, I would have just gone with the three wind turbines since 8 feet of ridge is practically worthless. If it had been a gable style roof with 40-50 feet of ridge then a ridge vent would have been fine.

  47. Luke says:

    Thanks for all of the helpful info and your answers, they’re very helpful.. I have a house that’s nearing 100 years old, and the heat in our second story is very bad even on 70-80 degree days. the heat remains even after it has cooled off outside. It probably takes until the early hours of the morning until it reaches a decent temperature upstairs. I checked the attic and I have about 4 ridge vents that are almost at the peak of the roof, 2 gable vents (one with a rusty old fan in it pointing outside) and the soffits are covered with rolled in insulation.. I’m planning on getting up there to clear out the soffits this weekend.. and see how big of difference it makes, if it still remains very hot, I’ll probably try slowing down airflow from the gable vents.

    The soffits themselves are strange though.. I can definitely see daylight through them from in the attic, but when I’m outside I cannot see where they open up at.. I think they provide sufficient airflow because I pulled the insulation out of 2 of them and could feel cooler air rushing in immediately

  48. Chase says:

    Ed,
    I’m sure this has been covered time and time again but for peace of mind I must ask. I live in Texas, it gets hot here. I am about to replace my roof due to storm damage. I currently have just 2 turbines on my 2400sqft house. The attic gets very hot. I have quite a bit of ridge and am going to have ridge vent installed instead of replacing the turbines. However I have an opportunity to do whatever needed to my roof at cost and am thinking about radiant barrier. Is radiant barrier something that should (or could) be installed over the decking (under the shingle) essentially preventing heat from even entering the attic? I fear this will destroy the shingle but would be easiest to install. Or does it have to be installed under the rafters so there is a gap? Also any other suggestions are welcome. Thanks

    • Ed says:

      Yes, this is an age-old question, but it has a simple answer: if there is no air gap, then heat is not traveling in radiant form. Therefore a radiant barrier would offer no benefit. I wrote an article on this question and even made a video, please take a look and hopefully you’ll have a better understanding on why it won’t work under shingles, but how you could look into some different options to add a radiant barrier in the roof assembly: Can I Install Radiant Barrier Under the Shingles When I Have a New Roof Installed?

  49. Chase says:

    Correction. I was given the choice of using polarium thermal barrier in place of the felt. Or radiant barrier under the rafters. What is your opinion on the products

    • Ed says:

      Personally, I don’t support the claims of Polarium because of the physics of radiant heat. Take a look at the article I linked to and hopefully you can see why it couldn’t work according to the definition of radiant heat.

  50. Christopher says:

    Hello Ed,
    I tried to read through as many of the posts as I had time for and saw couple similar situations but I’m going to ask for your recommendation anyway. Hopefully it doesn’t seem redundant since you’ve already answered so many.
    I’m getting a new roof due to storm damage on my 2700 sq. ft. house in Garland, TX, built in 1994. The roofing company is installing 2 ridge vents (one each on 2 different elevations) and 2 turbines. These are replacing passive vents that I don’t think do anything at all.
    My question is do I need both ridge vents and turbines? What I gather from your information is, if I just had the turbines, clear the soffet vents, and added AtticFoil I would get adequate ventilation. I believe I have 8-12 soffet vents around the house. Not getting the ridge vents could save a lot of money on the new roof.
    Thank you for all of the great information.

    • Ed Fritz says:

      Christopher,

      It depends. If you have a lot of ridge and a relatively low pitch roof, then I would go with a high profile baffled ridge vent. If you have a hip style roof and minimal ridge (less than 30-40ft), then I would go with 2-3 wind turbines. Go for the 14″ instead of the 12″ wind turbines. They move about 1/3 more air. I think you need to get up to about 20 clear and open soffit vents to be balanced.
      Of course adding AtticFoil Radiant Barrier will make a big impact on heat entering the attic and you should be fine with this amount of ventilation. You home sounds like the classic example of The Four Silver Bullets For Savings Energy In Hot Climates

      • Christopher says:

        Thank you. Great additional info.
        It is a hip style with fairly high pitch. The house is 2-story and the attic space above the garage is huge compared to the second story. Now that I look at it, the ridges are short over the garaged (they kind of make an S shape)but together total about 15 linear ft. There’s one that is about 12 ft. on the highest level of the of the second story.
        So it sounds like better money would be spent in adding soffit vents and the extra turbine.
        I appreciate your sharing so much knowledge with everyone free of charge. That’s quite rare these days. I’ll be talking to you when I’m ready for my AtticFoil.

  51. Josh says:

    Hey Ed,
    I just recently moved into a home built in the mid 80’s. It was orignally 2700sf and single story. Home is located in South Louisiana. Shortly after being built, the original owners added an additional 750sf upstairs. I have narrow, angled wood soffits with vents and 2 wind turbines. It is almost impossible to keep the upstairs rooms cool, especially this time of the year. All of the soffits appear to be free of any obstructions. What is my best bet for helping me keep the usstairs cool? Radiant Barrier? Spray Foam Insulation? Attic Fans? Replace the A/C!?!? Thanks in Advance Ed.

    • Ed Fritz says:

      Josh,

      I would look at my article for Hot Rooms In My House – How To Make Them More Comfortable I would focus on Radiant Barrier, then focus on the “Hot Walls” that face the attic. This can usually be fixed by putting foam board on the attic side of the walls and make sure you have BLOCKING between the two floors. This keeps hot/cold air from sliding between the floors. Finally, if all else fails, I’d look to a mini-split or multi-split AC unit.

  52. Neil Joy says:

    Good Afternoon Ed,

    I have two different sections of roof on my house due to the fact that I have a two story. The attic over the 1 story(smaller portion of the house) part is considerably hotter than the main attic. I have ridge vents installed on both roofs. In fixing a leak a few weeks ago, the roofer suggested that the ridge vent on the 1 story portion of the house is not long enough, therefore, not allowing enough heat to escape. I dont have anymore roofline on that portion of the roof to install additional ridge vents, so do you think I can just install a turbine vent and if so, what size and where on the roof can I mount this to keep the short circuting situation you mentioned. I have about a 1000 square feet of attic space that I am trying to ventilate. Thanks.

    • Ed Fritz says:

      Neil,

      I assume the two attic sections are not connected. Assuming you have plenty of soffit vents that are clear, open and allowing air INTO the attic area, I think you would be fine adding one 14″ Lamanco – Externally Braced “whirlybird” brand wind turbine. There are many types of ridge vents ranging from very effective (lots of open area – high profile baffled) to basically worthless (scouring pad type). I would not worry about short circuiting with a wind turbine. This happens mostly with a powerful electric fan. And, if you REALLY want to cool down the area, put in a radiant barrier. Call us, we will take care of you. 800-595-8772

  53. Hi Ed…I have an older, two story brick home with a new roof, put on last spring. This summer, my ridge shingles are lifting from the heat. I have 4 cans installed, but have no soffit vents to move the air, as whoever previously blew in the blown insulation stuffed it in everywhere. My question, is how do I get air moving up there to get the heat out before I lose my roof. Thanks so much.

    • Ed Fritz says:

      Joe, I’m not sure by what you mean by “I have 4 cans installed”. Are these some type of vents? It sounds like you have virtually no attic ventilation. If you have soffits, you can cut into them an install vents. Any insulation stuffed/blown into the soffits can be removed through the hole to the bottom which will open up a path for the air to enter the attic. If you can do this along with some topside vents than you should be OK. If you need more information visit the contact us page at http://www.AtticFoil.com or call us on the listed 800 number.

  54. Jeremy says:

    Ed: For attic ventilation in addition to radiant barrier. Would you use 1 or 2 electric attic fans on a roof that is 50′ feet long (1650 sq. ft) having the required amount of free and clear intake soffits for the roof’s square footage? Wondering if 2 equally balanced CFM rated electric fans would cause a “short circuit” or be a better airflow system than 1 electric fan (only soffits for intake and only the attic fan(s) would be exhaust). How far apart would you place these fans from each other if it was 2 fans? If you used 2 identical solar attic fans how far apart would you place them (assuming you need 2 solar fans to generate enough CFM of air flow that one solar attic fan could not do? If you did a solar fan (planned to use in the daytime) and an electric fan (planned to use only at night if nessasary based on a thermostat setting to allow the electric fan only to come on when the solar fan is not running—gets too hot and kicks on— would this set-up cause a “short circuit” even if the fans are separated on each end of the roof? Is this even a good idea (trying to save electric costs from the electric fan running all the time)….I know you will say it is only on a limited electric run time if I install attic barrier foil? Can you have too many soffit intake vents? If you have wind turbines on the roof instead of an attic fan how many should you have and how far apart from each other should they be? What happens if you don’t get your 8 mph wind speed on the roof for the wind turbine exhaust vents to run—there are not a lot of windy days and nights in hot Houston that I know of to generate this amount of wind speed? Do the wind turbines just because thermal hot air exhaust ports for the roof?

    • Ed says:

      You need to contact a roofer who installs static fans (like the turbines) to get cost info as well as how are needed for your roof. Personally, I would go with 2 or 3 14″ wind turbines. They work 24/7, in the dark, and are cheap compared to solar fans. Plus, with a typical 8 mph wind, they will pull a similar amount of air as the solar fan. Of course I also recommend you install a radiant barrier; it will keep so much heat OUT of the attic, that ventilation becomes less critical. Just like if you park your car in the shade it does not really matter if you crack your windows – the shade alone will improve conditions inside the car.

  55. Dicky says:

    I am probably going to install a radiant barrier in my attic, however, my attic is very high up. I know I can do most of it, but I can only reach so high. Is there a trick to getting the foil up there without an embarrassing and painful trip to the ER? Also, if I can only do a partial coverage with the foil, will that really be of any benefit? I have one electric fan at the top of my roof and soffit vents.

  56. William Brower says:

    Please forgive me if this has been answered.
    With a standard truss roof the truss centers are 24″.
    What if your soffit vents are spaced at 48″?
    Do you need to add soffit vents at the base of the the unvented 24″ inch spaces when installing a radiant barrier system?

    Thank you for your help.

  57. Tom says:

    Help! Getting a new roof on brick cape. No soffit vents or other intakes, and I am hesitant to add any of the drip-edge type vents due to ice build-up potential in buffalo, NY. Only exhaust currently is 2 pots on rear roof. Attic is hot and cold seasonally. Without intakes I have scrapped ridge vent idea. Should I put in gable vents? If so, should I close off pot vents or add more? Thanks – Tom

    • Ed Fritz says:

      You need soffit or other lower intake vents somehow to get air INTO the attic. I would look to using the drip-edge vents. Then you probably need to increase the topside exhaust vents. This can be done by adding more static vents or other type of exhaust vent. You want air flowing through the attic in the cold weather and the attic SHOULD be COLD to keep the ROOF COLD to prevent/reduce ice dams. We have had many customers see a significant reduction in ice dams after installing AtticFoil Radiant Barrier. The radiant barrier works with the attic ventilation do help keep the roof colder.

  58. ron says:

    Good articles.

    Just moved into a 35 year old house, Dallas TX. VERY NARROW eaves, like 5 inches, a few eave vents, but heavily painted over, so I think they are essentially blocked.

    Have 6 whirlybirds. They barely move. No ridge vents.

    As the soffits are recently painted, and the roof is new, I don’t want to “disturb” existing things except as is essential.

    There are 2 moderately separated places where there are large overhangs. They are nicely separated relative to the attic area.

    So, I am thinking of just adding substantial vents in these two areas, until such time as I need painting or roof work.

    Was also wondering – I can see that power fans at the top of the attic would be bad for my situation – they would probably just pull conditioned air from the house.

    I am wondering – why not install a whole house exhaust fan (or something smaller) in the areas where I can install large vents. This would suck massive amounts of ambient air into the attic, which primarily go out the whirly birds, right?

    Am interested in your ideas. I have never seen a discussion of putting power fans at the soffit level, to pull ambient air into the attic.

    • Ed Fritz says:

      Ron,

      If you have some places to add some soffit vents, do it. I would use a wire brush an try to clean the existing soffit vents too. You will be amazed. I’ve seen “broken” wind turbines start spinning like new once the soffit vents are cleaned and air can come INTO the attic. Or, by adding or replacing a bunch of new ones.

      I think the idea of putting a large fan in the soffits is a waste of time and money. The air GETS hot from flowing along the bottom of the roof and actually COOLS off the roof, it a cooling effect. This is why we want air to be around the perimeter rather in one place as you suggest. If you have a decent amount of air coming and going out you can only cool the AIR off. This does virtually NOTHING to the surface temperatures. Just like a fan blowing on your sunny driveway will not cool it off much. Often, people tend to get hung up on the AIR temperature when they should really worry about the SURFACE temperatures in the attic. This is why an AtticFoil Radiant Barrier is so effective. Did you see my short video on the basics of radiant barrier? Don’t over-think it.

  59. BigWaveDave says:

    Hi Ed,
    You give great advice on this site, well done!
    This is my situation, my house, located in Southern California, is around 1700 Sq Ft, we have 1 12″ Whirlybird, 3 gable vents, 1 of them has a fan and thermostat. We just insulated our home this past weekend, it was around R4, is now R38. Well, we are still experiencing extreme heat buildup in the attic, especially late evening and into the morning. I did notice we do not have soffit vents,, since we have eaves,, just soffit end blocks with 3 2″-3″ holes drilled in them. 4 vents total for the entire house,, the house also has an addition, about 400 Sq Ft that only has a gable vent,, no soffit or end block vents at all,
    I am totally lost, after spending $1700 to blow in insulate our attic, without any improvement,,,
    What do you recommend?
    Thank you!!

    • Ed Fritz says:

      Dave,

      This is fairly common problem. Adding insulation can sometimes lead to the law of unintended consequences. Insulation works well to SLOW down heat flow into the home. However, it also acts like a “Sponge” for the heat and will HOLD it long after the sun goes down. The top surface of the insulation can easily reach 140º or more depending on the location/roof/ventilation etc. The insulation becomes a hot blanket over the ceiling that will continue do release heat long into the night. As you know, I manufacture and sell Radiant Barrier Foil. The purpose of radiant barrier is to keep the insulation cooler by NOT allowing it to heat up from radiant heat being emitted by the roof. With a radiant barrier installed, the top surface of the insulation will only be a few degrees above the ambient (outside) air temperature. I would look to adding Radiant Barrier Directly Over The Attic Insulation – < -Follow Link For Instructions. Stapling up would probably be best, but it can be difficult and you will probably trample/compress the insulation you just bought. You can use a pole with a nail taped on the end an push the foil back to the soffit with minimal disruption to the insulation. Just create a "snow path" through the insulation and fill it back in as you work your way out. Try to cover as much of the insulation as possible, but don't worry if you miss some spots. The radiant barrier has a cumulative effect. Finally, I would look to try to add some more intake for ventilation at the soffits if possible. Good attic ventilation requires BOTH intake and exhaust vents. Ventilation can only do so much, a radiant barrier will have the biggest impact. Any other questions, please call us on the 800 number at http://www.AtticFoil.com

  60. Carol Maguire says:

    I have a 14 yr old single story Horton home 1950sq ft. My contractor recommends twirrly vents and replacing the square vents with the new roof insurance has approved. I’m trying to learn if ridge vent is the way to go instead. Do no have radiant barrier either. Concerned about water or varmints getting in attic. There are soffit vents, and large vent with areplaceable filter, one in the garage and in front porch ceiling, installed awhile back after an energy audit and new AC system were installed.

  61. Jim B says:

    I need some help. I have a house in Ohio that was built in 1971.
    My roof above the living space is 1100 sq feet. I have 4 8×16″ soffits in front and 5 8×16″ soffits in the back and 3 static vents and a power attic fan on top. I have had condensation on nails in the roof in the winter, and I need to fix this asap.
    How many static vents do i need? Should I continue to use the power fan with the static vents? Or should i go a different route and go with wind turbines? And if I go with wind turbines, can I use the power vent with wind turbines? I am really stuck. Thank you.

    • Ed Fritz says:

      Jim,

      I would look to make sure the soffit vents are actually clear and open and allowing air to enter the attic. Most likely they are dirty and clogged. I would turn the fan off and see what happens. The fan is probably just sucking air in through the static vents and bypassing the soffits. If the condensation is worse the lower in the attic you go, this would support the idea that very little air is coming into the soffits. Use a nylon wheel brush and brush from outside the house. If your soffit vents are good, then I would consider switching the static vents to wind turbines. Leave the electric fan off.

  62. Steph B says:

    Hi Ed,
    I am in central MA and re-roofed my house about 4 years ago. We get a lot of snow. The roofer put in ridge vent but no soffit vents!! I have 3 teenage boys and one other thing is that originally the two bathrooms vented directly into the attic, although one was vented to a soffit, but lots of moisture was wrecking a window below that soffit and we would get ice there and it was obvious by the melted snow on the roof above that area that the vent wasn’t really working too well. So, we looked at venting with insulated venting to a gable window, but last winter it was obvious this was not working due to melted snow above bathrooms on the roof.
    so, help!! what should we do to get the moisture out of attic and ventilate it well? I know we need soffit vents, we have two tiny gable vents and the ridge vent and the bathroom venting is an issue too and I haven’t been able to find a good solution for that. i am afraid if I don’t get this addressed we will be having mold issues up there…. I would love to do it myself but the second story is high up, but I don’t know who to turn to for help who will be fair and reasonable 🙂
    thanks for any input you have!

    • Ed Fritz says:

      Yes, you definitely need to start with soffit vents. It sounds like you have NO place air to get INTO the attic. Installing 2nd floor soffit vents can be tricky and dangerous. I’d call around to some roofing companies or roofing supply houses and ask who buys a lot of soffit vents. Then, call them to see if they can install some for you. Just make SURE the hole the soffit opens up into the attic and not a tray ceiling. Then, I would make sure the bathroom vent fans are sealed tight. Use “Great Stuff” foam or to seal them up and make sure the vent goes OUT of the attic. You may need to roofer to install a vent cap or two. If you do all this, you should see a significant reduction in moisture issues.

  63. elle says:

    Hi Ed – Great website and advice, you’re an invaluable resource to folks like me who have no one to help them!! I just bought a 1948 plantation home, 2000 sq ft. on the North Shore of Oahu (gets a lot of wind) and due to the tropical climate no need to keep house warm in winter. It is a high pitch roof – massive attic, with only soffit ventilation around the sides of house – they look original, small holes, clogged old vents, only 22 around the house, the holes looks to be about 2″x12″ w/vent covers 4″ x16″. Black shingle roof, 3 years old. There appears to be no other ventilation on the roof top itself. There is no insulation in the attic. I installed Mitsubishi mini-split a/c system so no duct work in attic fyi. This is my first home and I know next to nothing about any of this, and as a result have everyone trying to “sell” me their products, even whole house fans as a solution. I’m trying to decide the best route for cooling our home in a tropical climate – the home inspector said the first thing I need to do is vent the attic because temps were hitting 140 in the late afternoon, while it’s 80 degrees outside. After much research and reading your posts and comments above, my guess is that I should make/cut the soffit holes bigger and get new covers (although the only covers I find at Home Depot/Ace seem like they don’t allow much air in – would ugly screens, painted, be better here for allowing more air through?) as well as adding more soffit holes? Add radiant barrier (to the pitch of attic or floor? confused on this too) AND/OR 2 or 3 14″ wind turbines. Can you kindly advise? Feeling desperate about doing the right thing on this! It’s also nearly impossible to find people to do any of this work on the North Shore. I have a Solar Guard guy who will come out to install their product as the radiant barrier but it’s very expensive – any opinion on using that vs. Attic Foil? I’ve read about the differences b/w products on AtticFoils website but don’t have anyone to install the do-it-yourself AtticFoil. Single mom, just trying to make our first home cooler!!
    Many thanks in advance:)

    • Ed Fritz says:

      Elle,

      Thanks for the question. Here is what I would do. I would try to “open up” the attic. This FIRST thing I would do is have some holes put in the top of the attic. Yes, I would go with 2 or 3 14″ windturbines. Then, I would see what happens. If it is STILL hot (air over 120 degrees) then focus on cleaning/changing/replacing the soffit vents. This will allow air to come INTO the attic. Once you have some air flowing through the attic, I would add some Insulation to the floor of the attic. If you have access to a Home Depot/Lowes they will loan a blower if you buy some insulation. This is a pretty easy DIY project if you can find an able bodied person. I would look for a college student or handyman type. Finally, since you have NO ductwork in the attic I would get the same person to lay out http://www.AtticFoil.com over the insulation when it is done. Yes, I sell AtticFoil but it’s far cheaper than Solarguard but only has a Solarguard REAL R-VALUE of about 1. You can call us anytime. We will coach your handyman through the process.

      Here is an article called “The Four Silver Bullets For Saving Energy In Hot Climates”. This is basically your home except you have no ductwork in the attic.

  64. Attic ventilator says:

    Ridge Ventilators are natural extract ventilators suitable for ridge mounting. They incorporate low profile and weight with maximum exhaust flow. The low profile and modern design gives an unobtrusive appearance without adding greatly to the wind load or dead load on the building structure.

  65. israel says:

    Ed,

    This is a great website.

    I have about 2500 square feet of attic space with about 4 different zones in the attic with the main zone being a 4 sided pyramid…last summer I was miserable…first summer in the house…high humidity 55-62% without dehumidifer going..high particles high…chemical readings….high co2…is it possible for attic air to get drawn into the house because of inadequate ventilation and cause this type of situation? Is it possible for attic heat to cause such high humidity readings? I live in fort worth texas and my house has about 7 inches of cellulose in the attic…is that too little? Also I have two turtleback vents about 14″ at the top of the main part. But no roof ventilation at the top of 3 gable roof sections that come off of the main section. Soffit vents all around but two thirds have baffles in every other rafter because of high ceilings.

    I was going to do a door blower test to test house tightness..but heard most builders do this type of test..so I was trying to figure other sources when I thought about how hot my attic was last summer…house has a dark roof.

  66. Michael says:

    Ed;

    I am experiencing truss uplift during the winter months on a 4,000 sqft. Single story ranch house located in North Dakota. This is causing some sheetrock tearing on some areas of the the ceilings. The home was constructed in 2006, and has shingle over ridge vents. The soft has perforated aluminum soffit vents, and attic chutes with about 36 inches of blown in fiberglass insulation.

    Typicaly higher moister on the upper truss chords could lead to truss uplift.

    I have checked the attic at zero degree temps and do not see and frost from condensation on the nails that went thru the roof sheathing.

    Should I install 2 or 3 power roof vents, and install soffit vents 8” X 16” in the areas close to the chutes?

    Please advise…

  67. VanInTexas says:

    Just spent the last hour reading thru all these posts. You’re very kind to address people’s individual questions, and I hope you’ll answer mine.

    Believe it or not, my question starts with a Foundation issue. Actually, a professional Structural Engineer first brought up the subject of attic ventilation with me when discussing foundation issues I (thought) I was having. He schooled me on the importance of home and attic ventilation as it relates to the maintaining a home’s structural integrity.

    I have soffit vents which (I’m embarrassed to say) have never been cleaned. [Of course, the SE recommended cleaning those.] He also recommended replacing the static vents with turbines for better air flow (also have ridge vents).

    So the questions are: I’m physically unable to clean the soffit vents myself. What profession (roofer?) should I seek out to clean my soffits? Other question is, do you agree with replacing static vents with turbines? Tho’ we’re dealing with heat usually in N. Texas, we have some pretty cold days in the winter, and I’m concerned about the turbines sucking the warm air out of the house/attic (as well as the cooled air from the house in the summer). And if you DO recommend the turbines, should they replace the statics (as in, use the same holes)? If not, do the statics need to be closed up? What about the ridge vents (need to be closed up)? Your thoughts?? Thank you!

    • Ed Fritz says:

      Unfortunately, there are not any professional soffit vent cleaners. It’s actually so easy anybody (high school kid, handyman) with a ladder, nylon brush and a leaf blower can clean them. Just brush the bottom (from the outside) of the vents really good with a nylon brush – like a wheel brush. Then use a leaf blower or air compressor to blow through the soffit vent to move any junk that may be sitting on top of the wire mesh. If the soffit vents have been painted closed, the you are probably better off pulling them down and replacing them.

      As for the static vents/wind turbines/ridge vents, I would hold off on doing anything until you clean/open up the soffit vents. You will be amazed on how much cooler the AIR in the attic will be by just opening up the bottom. I would be hesitant to mix wind turbines and ridge vent. Mixing static vents with ridge vents is not ideal, but really is not a big deal.

      Finally have you considered installing a radiant barrier? Ventilation is nice, but the equivalent of a shade tree is even better for reducing heat gain into the home.

  68. Nick says:

    Howdy,

    I live just north of Houston, TX so we have very hot summers and thus very hot attic (130+). I of course would like to cut down on the cooling cost, but the main reason I want a cooler attic is that we have a 1.5 story house. Basically the room on the second floor is sitting inside the 130 degree attic and it is very hard to keep the room cool. We are planning on wrapping the room with some more fiberglass insulation to try and help keep the room cool. The next step is keeping the attic cool. We are looking at adding radiant barrier but are also considering extra ventilation. We have a hip roof that the original builder decided to put a ridge vent in for some reason. The house is about a 2000 sqft foot-print with about 8 feet of ridge vent at the very top and at about 6 feet lower down there is another 10 feet of ridge vent above the garage. This seems like very little ventilation to me. What would you recommend to increase the ventilation in the attic and create a proper flow? Also, are there any special installation steps needed for a hip roof since most of the rafters don’t go all the way to the top and instead intersect the next angle of roof?

    • Ed Fritz says:

      Nick,

      As for the hot room, I would start by putting 3/4″ foam board on the attic side of the walls. This adds r-value and “zips up” the insulation between the studs to reduce air movement which greatly reduce the effectiveness of the insulation. Did you see this article I wrote on Hot Rooms In My House? Also, look to see if you have any open chaseways that are allowing hot air to come in under the floor. Call us for more details.

      Radiant Barrier Foil Insulation will make a lot bigger impact than attic ventilation on keeping the attic cooler and the upstairs rooms cooler. What I always recommend is to add radiant barrier FIRST and then see what the air temperature is below the foil before messing with the ventilation. If the AIR temperature below the AtticFoil is still more than 10-15º hotter than the outside air it means the air is getting “stuck”. Basically like a clogged drain and is backing up into the attic. ONLY then would I increase the attic ventilation. Start with cleaning or opening all soffit vents and then I would put in a couple of 14″ wind turbines and cut the foil below the wind turbines. NO attic fans!!

      As for hip style roofs? Simple. You want the air to have a path from the bottom to get up and out. It will find it’s way like water as long as it has a path. Simply, cut a hole or slit at the top of each hip and the air will continue to the top. Here is picture from my website showing this: Radiant Barrier On Hip Roof

  69. joseph siegel says:

    I just moved into a 1 story stone ranch in Indiana. Attic is approximately 1400 sq feet. I have 6 passive roof vents. No ridge or gable. I have a large overhang around the house with aluminum style soffits. Every few panels is a set of two panels with those tiny holes. I pulled one off and its just wood underneath. So from what I can tell, my top priority should be soffit vents right? Can I just take off the aluminum soffit, cut a hole in the wood, make sure its clear of insulation and then put the soffits back on, or should I install a vent over the hole, and then put the soffit back on?

    Here is a picture of what my soffits look like:

    http://www.doityourself.com/fo.....cn9729.jpg

    • joseph siegel says:

      I just want to add that its 48 degrees outside, the sun is very bright and I went into the attic today and the temp measured over 90 degrees, so clearly, there is no airflow going on and I am hoping soffits will drop that considerably?

    • Ed Fritz says:

      It does not really matter how the “hole” is made. You just want air to be able to flow freely from the outside to inside the attic and then out the top of the attic.

  70. Frank says:

    Hi there,
    I’m installing new GAF roof. Currently have soffit all around, 2 gable vents on each side of attic, and electric fan. Roofer suggested removing fan, and installing ridge vent. He said ridge vent will work better since it runs through whole attic, as opposed to fan which just removes air over one section. What is your opinion of ridge vent? I feel that it won’t move air as quickly. I live in NY.
    Thanks.

    • Ed Fritz says:

      I would tend to agree with the roofer on this one. A good ridge vent will provide excellent ventilation without using any electricity. Plus a fan combined with gable vents really does not provide great overall ventilation. The fan tends to just pull air in through the closet holes (usually the gable vents) and the lower part of the attic stays stagnant.

  71. Todd W. Roat says:

    Great informative site. Ive learned so much so quickly. We live in Cincinnati, OH. Standard complaint in two story home: 2nd floor noticeably hotter in summer.

    We have adequate insulation, but going to add a little more. Soffit vents but have been covered with vinyle siding soffit with the holes in them. I have a very low Hip roof so getting to to the location where roof meets ceiling is next to impossible, and I cant tell if the vents are covered with insulation or open and free. Any tips for this? Attack from outside?

    I also have probably too many static vents: 4 static vents and a ridge vent.

    Roofing contractor seems smart but wanted your opinion for intended solution.

    1. Use felt to seal off existing static vents to optimize turbines.
    2. Will keep ridge vent vent.
    3. Install 2 turbines.
    4. Make sure soffits are clear.

    Reasonable first approach to cool upstairs? Ant thoughts on wind generated turbines versus electric motor driven roof exhausts?

    Thansk!

    • Ed Fritz says:

      I’d try to focus on the soffits. Attacking from the outside is really the only option. Vinyl soffit are usually pretty worthless as far as providing ventilation unless the whole soffit is perforated AND there is plenty of open space behind them. Assuming the ridge vent is a high profile, baffled vent, I would keep it and not add any more turbines and stay away from powered vents.

      Have you looked at a Installing A Radiant Barrier? It’s easy to install and it makes the attic ventilation less of an issue. If the heat never gets into the attic to begin with, then you don’t have to worry about getting it out.http://www.radiantbarrierguru......ments-form

  72. Julie says:

    Hi Ed,
    Your Website is incredibly helpful. Thank you for sharing your knowledge with us. I live in St. Louis MO where the summers can be 90+ degrees for 3+ months. Our home was built in 1930 and has the original clay tile roof with NO ventilation – no intake vents, no exhaust vents. There is just insulation blown on the attic floor. And we have A/C ductwork up there. We are replacing the roof with Certainteed architectural shingle because the clay tile is too expensive. Should I keep the attic enclosed with no vents at all, and just use the existing insulation on the attic floor and install new radiant barrier? Or should the roofer install Drip Edge venting for intake, plus 4 turtles or ridge vent to exhaust? The attic space is a simple 20 feet by 50 feet rectangle and the home has no soffit space. I really appreciate your input.

  73. angel stone says:

    OK here is my question and I can’t seem to find the information anywhere. I live in a duplex which has attic side vents, not roof vents or soffit vents. So my question is this. is the attic side vents enough or should I add the vents in? The reason I ask is I’m about to have to replace the dry wall on my living room wall along the window; Though I am not sure if the damage is from the roof leaking when the last owner had the house and they just painted over the damage for the sale or if it is condensation because of poor ventilation in the attic

  74. Diane says:

    I live in SC with summer temps close to 100 degrees. Currently have 2 attic power vents and soffit vents. Getting a new roof with ridge vent. Should I keep the power vents or have the roofer remove them? Also, the soffit vents are continuous – about 2 inches wide in middle of soffit. They are mostly painted over. Should I replace them with something newer or just try to clean/unclog? Thanks much!

    • Ed Fritz says:

      I never would recommend power fans. High profile ridge vents are the way to go if you have enough ridge. I would do a “smoke test” in the attic to see if the soffits are allowing air to come in. If they don’t, then I would clean or replace them.

  75. marie says:

    Hi,

    I live in Texas, I know it gets hot! My house was built in 2010, no shade whatsoever. 2100 sq ft. We had foil Radiant Barrier put in a couple of yrs ago. However we still feel that it is pretty warm in our home. High tray ceilings in every room. Soffit vents look clean, but some only cut at half moon. Can’t see if the baffels are adequate not due to Radiant Barrier. Would adding more soffits help with air flow to cool the attic?

    Thanks in advance for you input.

    • Ed Fritz says:

      Adding more soffit vents would help some assuming that there is a clear path to the top of the attic. Tray ceilings can be tricky. Pull the foil back and try to shine a flashlight down the baffle and see if it is clear to the soffit. If you are still having comfort issues, I would check for duct leakage and have your ac system really checked out by a reputable company. Duct leakage is like leaving the front door open. You are just constantly mixing hot air into your home. The hotter it gets and the more you need your ac, the hotter the air coming it gets too.

  76. Beth says:

    Hi Ed,
    You’re remarkable generous in answering questions, so here goes. I have a square foot pre-1913 wood frame home in north Florida that originally had wood shingles, now 3-tab asphalt over board decking. I’m about to reroof, probably with architectural shingle, possibly metal. There is a large 11:12 gabled attic space (about 1000 sq. feet under the roof) with two off-ridge vents placed high on the back (south) side of the roof, but there is nothing letting air in from below. No soffits. The historical district rules restrict what I can do on the front (north) of the house. There is a gable-vented space below the 3:12 porch roof on the north, but it does not tie into the main attic. There is a large window (30 x 60 in.) in each of the main attic’s gables (east and west), large enough that the bottom is only, say, two feet off the floor of the attic. One idea is to remove the off-ridge vents, add a ridge vent, put a louvred screen like a gable vent on the exterior of each gable window, then open the windows to provide air intake to balance the ridge. I’d have to close the windows for a big storm. Another idea is to add a ridge vent and move the off-ridge vents lower on the south roof to provide intake. Which would work better? Any other ideas? How much does it matter that there can be no intake on the north side? There’s blown-in insulation on the floor of the attic. I don’t think drip-edge venting is Florida approved. Thank you.

  77. Mark K. says:

    Hello Ed,
    I wanted to ask your advice for my circa 1850s home that has no atic ventilation at all. It has a very old seam metal roof on wood boards. My guess is what ever air enters eventually passes through the roof since it’s not air tight. But probably gets pretty hot up there in the summer. The metal is very thick and in excellent shape, for this reason I’m not planning to replace it or make cuts for vents.

    I plan to install HVAC equipment and duct work in the attic to provide central heat and AC. I had considered spray foam insualation, sprayed to the roof deck to encapsulate the attic (since there is no ventilation), but I’ve been told that will create condensation that will eventually rot the wood boards. As an alternative, I’m considering your attic foil along the inside rafters, about a 10″ gap from the metal roof deck, and attach foam isulation boards on top of the attic foil, on the most inner side of the attic. The layers from the inside out will be foam board insulation, attic foil, 10″ rafters, wood and metal decking. And again, no ventilation at all. Do you see any problems with this approach?

    Thanks for all of the information you have supplied.
    Mark K. The home is in Central VA (hot summers, cold winters).

    • Ed Fritz says:

      Mark,

      I love foam encapsulated attics for new construction. When I built my home, we went full foam and it’s incredibly comfortable and efficient. Moisture should not be a problem is you have a properly sized AC system. I would look to installing some type of inverter system (Mitsubishi, LG, Sanyo, Daikin etc.) that will run at part-load and provide better comfort and dehumidification control. They are also very efficient heat pumps to heat in the winter.
      I would lean to either opening up the attic and vent it or go all in and seal it up with foam. Your idea seems like it is somewhere in the middle.

  78. David Hernandez says:

    Hello. I have a 1.5 story house, built in 1962. I installed AtticFoil stapled under the rafters of the TOP attic and replaced the insulation between the joists (R19) then added R13 across it [total of R32].

    I have a question about the SIDE attics. The side attic shares a 4 foot wall with a room inside, then there is a slanted roof line with really old and damaged fiber-glass with a bit of aluminum facing] leading up to the TOP attic.

    I’ve replaced the insulation on the wall (R13 between the studs) and I’m thinking I should staple AtticFoil to the WALL over the insulation. Is this the correct thing to do? Should I do that PLUS also apply AtticFoil to the ROOF (stapled to the rafters)?

    My concern is that any heat channeled by the AtticFoil up into the TOP attic. The insulation on the slanted part of the ceiling between the two attics is really old and is not intact.

    So.. Any ideas? Wall only? Wall + Roof? If I do Wall + Roof, should I leave a gap like at the top of the house, or should I seal it so there is no gap.

    Dave

  79. David Hernandez says:

    P.s. In the customer installation pictures on atticfoil.com you have this “Knee walls that share space with a conditioned (heated/cooled) room should be covered with a radiant barrier. First, make sure there is traditional insulation between the wall studs, then use the foil to wrap the sidewalls and covered the floor in the pockets on either side of a room on the same level as the attic”. I’m thinking maybe what I have is a Knee Wall. And this may be what I was looking for. So I would apply the foil to the wall and then the FLOOR, not the roof?

    • Ed Fritz says:

      David,

      You want to “zip up” the wall and make it more airtight. If you REALLY want to do it right, I would put a layer of 3/4″ foam board on the attic side of this wall. This will “zip it up” and provide additional r-value and significantly reduce thermal bypass through the studs. Take a look here on How To Keep Walls Cooler Then, I would add radiant barrier either to the roof if you are in a hot area and to the wall and the floor if you are in a cold area.

  80. marie says:

    Hi Ed,

    Thank you for all your helpful insight. We had the foil radiant barrier installed, and added additional sofits, insulation up to code. Our attic still feels pretty hot. Now the company we used is, suggesting that we lower the ducts on to the insulation and cover them with more insulation. I have never heard of this…..what are your thoughts?

    Appreciate all your help.
    Marie

    • Ed Fritz says:

      Marie,

      Thanks for the question. Before you do anything I would try to quantify the exact temperature inside the attic below the radiant barrier foil. Saying that it “feels pretty hot” is hard to measure. If the foil has good coverage and the attic is well vented then the air below the foil should not be to much hotter then the outside air. Maybe 10-15 degrees. As for burying the ducts below the insulation? I think it is a great idea and have done it many times with great results. There is really no reason to hang ducts in the attic other than to keep them from getting damaged. A typical duct has an r-value of between R-4 and R-8. By burying the ducts, you can significantly increase the effective r-value of the ducts and reduce the heat gain or loss as the air travels through the ducts.

  81. marie says:

    Ed,

    I can not begin to tell you how much I appreciate your quick response. Forgot to mention that we have 4 airhawks vents pretty close to the ridge vent. Do those need to be coverd to allow proper air flow throught the ridge vent and sofit vents?
    Thanks again for all the help!

    marie

  82. Marilyn says:

    My ridge vent was installed some years ago along with the soffit vents in the 1950s part of my home. How do you clean out the ridge vent? It mostly has spruce needles in it that have accumulated over the years and must affect the air flow.

    • Ed Fritz says:

      Good question. I think if you had a powerful leaf blower and hit it from inside the attic would “push” a lot of it out. Then hit it from the top.

  83. Tom says:

    I live in the phila. pa area and have a house that was built in the 1940’s. The attic ventilation consists of 2 louver type vents on each side of the roof. There are no soffit vents
    I need a new asphalt roof. The roofing contractors I have talked to are of 2 minds. One side says add ridge vent and edge vents(smartvent) the other side says use attic fans. Not sure which way to go.

    • Ed says:

      As far as ventilation, I’ve done hundreds of homes and I think passive is all you need (with a few exceptions) in most attics.

  84. Doug says:

    Hi Ed,

    I have a 1300 sq. ft., 2 story home which was built in 1889. I reside in the northern Finger Lakes region of, NY state. I am in need of a new roof. The attic has the blown in paper insulation. There are no soffit vents. There is one small gable vent.

    Right now we are just taking bids. One contractor is talking about installing a gable vent with a exhaust fan. Not sure I want to go that direction with the type of insulation we have in the attic. What would be your recommendations for venting?

    Thank you, in advance.

  85. Mike says:

    Hello from South Florida. I recently inherited a house built in 1955. The house has both a sloped and flat roof with vents on the bottom and a ridge vent on top. Where the screened-in back porch starts, which is where the flat roof starts, the attic stops but is exposed at the entire back length of the house. There is about a 2 feet gap that has allowed cats to get in nightly to the attic as well as allow the attic heat to escape and make the back porch extremely hot. I’m a roofing novice so I hired a carpenter to cut wood to plug these holes so the cats and heat problem would stop. I thought this would also cause the a/c bill to go down inside the house. However, I noticed the a/c has been running more, having the opposite effect.

    Today an exterminator who is also a carpenter opined that enclosing the gap was a very bad idea and would trap the heat inside the attic and actually make my house hotter, in addition to allowing bugs and mold the potentially propagate in the attic if any moisture ever got in. He suggested to either take the boards out and put up screen or to put holes into the board and screen those holes up.

    Did I mess my attic/roof ventilation up by boarding these gaps up? If so, will cutting screened holes into these boards every couple of feet cure this problem? Please help!

    Thanks, Mike

  86. Clueless Teresa says:

    WOW! Stumbled across ur great website! Thank you, thank you, thank you! Have an all brick, cape cod?, two floors, high pitch, 1942 built house in Chicago. Unfinished attic with R13 insulation. Getting new roof due to wind damage. Currently, NO SOFFIT; has window on each end of house; three static vents each side; house faces east/west. What should I get done for positive air flow? Was thinking of adding a power vent, but after reading all blogs-doesn’t sound like good idea. One roofer says he’s seen a lot of unnoticeable leaks from ridge vents (water trickle in basement traced to ridge vent. replaced ridge vent and still water. finally removed ridge vent and no water). Also, what is difference between function of wind turbine and static or roof vents?

    • Ed says:

      Wind-driven turbine vents do move more air than flat vents (but only when the wind blows). A largely arbitrary rule of thumb that’s been adopted into most building codes calls for 1 sq. ft. of vented area for every 300 sq. ft. of attic space. A good idea is to utilize this rule to do about half the vents as intake (soffit) and half as outtake (exhaust via turbine, ridge, etc); it’s hard to overventilate an attic — generally speaking, more is better. Just remember to make sure your area on the attic floor (the area shared by the living space and the attic) is well sealed to prevent leaking air from the interior to the attic space and make sure your soffit vents remain open and unclogged so they draw enough outside air into the attic space.

  87. Clueless Teresa says:

    p.s. would radiant barrier be placed inside of attic over beams or under roofing deck? forgot to mention the attic so hot in summer that the glue which holds the soles of my shoes together melts! The space is used as a big closet for storage of clothes, linen, dry food, paper goods, books, Christmas, etc

    • Ed says:

      The easiest and best option is to staple it across the bottom of the rafters from inside the attic. This eliminates thermal bypass through the rafters and creates a cooler attic space for your storage.

  88. Larry says:

    Went in my attic to add an outlet and discovered that my front porch soffit area which is 7’x7′ is open to the entire attic! Shouldn’t this have been walled off? It’s like having a huge hole cut into the attic. Just doesn’t seem right. Ed what do you think?

    • Ed says:

      Well it’s not necessarily a problem, and some homes do have those areas walled off. However, unless you’re seeing an issue with ventilation or furthermore, moisture accumulation, I think it’s ok.

  89. Kyle says:

    My question is on a roof system that uses standard soffits and vents (4 ridge vents and one wind turbine) and has blown in insulation. The house has what looks like panels running from the edge of the soffit about 4 feet up the rafter. One side has these attached to the rafters the other side has them laying down some or partially attached or completely on the insulation. What should be done about this? Also the covered patio and garage have no insulation over these two rooms and they are open to the house attic area. Does this decrease efficiency or present problems?

    • Ed says:

      On the panels – I’d have to see a photo to know exactly what we are discussing here. As for the patio and garage area, that is typical to see no insulation – in these non-conditioned areas, you just need a layer of radiant barrier to control the heat gain. You can lay it over both areas from the attic side to help the areas below the attic cool down and you can also address garage doors that catch sunlight by following this install method for radiant barrier: How to Install Radiant Barrier on Garage Doors to Stop Heat Gain.

  90. paul says:

    Ed – I live in the mid-Atlantic East Coast zone. I have a low pitch (4:12)ranch house, with 3,000 sq feet of attic floor area, 14 soffit vents and 2 wind turbines, as well as couple of static vents. I need a new roof. One high-end roofing co says they see evidence of condensation and staining around roof nails coming through the deck, indicating inadequate ventilation – they suggest 2 powered fans, because the low pitch roof does not permit good air flow. Other roofers suggest ridge vent or adding a 3rd turbine.

    What is the minimum pitch for effective ridge venting from either airflow/ventilation, or from potential ice/snow/rain/water infiltration viewpoints?

    I appreciate your help and being a great resource and knowledge base in this area…..paul

    • Ed Fritz says:

      First, I would check the soffit vents to make sure they are clear and open. I would physically put a smoker below them and make sure air is being drawn into the attic. Ridge vents work very well on low pitched roofs. Especially if you use the high profile “baffled” type. As the wind blows over the roof, it will actually “suck” air out of the ridge vent. It also keeps rain from blowing in. I would stay away from power vents. Never a good solution. I think a good ridge vent combined with clean soffit vents (maybe install a few more) you should be OK. Do not mix ridge vents with other exhaust vents.

  91. Thomas says:

    Hi Ed,
    Great website; I’ve learned a lot. Thank you for your time.

    I live in a Cape Cod in KY. Last spring I added a gutter intake vent system when I replaced my roof. Also paid some guys to insulate the attic floor and knee walls and they added those styrofoam channels along the roof ceiling to make sure air can move from bottom to top.

    Ventilation has certainly improved, and the attic temp is much closer to the outside than it used to be, yet in the summer, the attic still gets hotter than I would like.

    My question is: How to I install radiant barrier, being that the styrofoam channels are in place? Do I remove them, then install radiant barrier against the inside of the wood rafters, then replace them? How can one install radiant barrier in the small space between the roof and the slanted ceiling in the “finished” room below? Remember, this is a Cape Cod.

    Thank you so much for your help.

    • Ed says:

      You can leave the baffles (styrofoam vents) in place and just staple the foil across the bottom of the rafter ends. Install guide is here:
      Installing Radiant Barrier on Rafters
      The navigation of the tighter spaces in a Cape Cod might be cumbersome, but as long as you can get a piece of foil between the roof and the insulation covering the living spaces below, then you’ll be good.

  92. Thomas says:

    Ed, just to clarify, my Cape Code 2nd floor has a conditioned room, with the sides and top unconditioned. My goal is to keep heat out in the summer; it’s usually fine in the winter.

    I would like to know “where” I install the radiant barrier in the “unconditioned” spaces. Everything I read on your site says you would install on the rafters, as close to the roof as possible, in order to keep the heat out.

    Thanks for the help.

    • Ed says:

      Thomas, yes – you can install it on the rafters to keep the triangular pockets of attic space on either side of the 2nd floor room cooler, this will help that room. Then, if you can get a layer of foil in the area ABOVE the 2nd floor room, that would be ideal; even if you can only lay it across the ceiling joists of the room, that will make a significant difference in that room being more comfortable. Take a look at this page to get some more info on these small areas around rooms: Radiant Barrier on Kneewall Areas

  93. Ryan Mallary says:

    I have a quad level home on the SW Chicago suburbs. The home was built in 1986 and features a new roof with no soffit venting. The 2nd story attic space is roughly 1500 sq ft and gets very hot in the summer as you could imagine. I currently have 2 mushroom cap passive vents and do little to nothing to reduce the temperature. My HVAC works overtime as still does not cool my second floor master bedroom. Having just painted the T-111 siding and the soffit spaces along with countless other projects has left me stopped for cash. I really would love to pull all the soffit and install perforated vinyl but financially it is not an option this year. If I am reading this properly you would recommend installing soffit vents through the plywood and taking back the blown insulation to allow proper flow. I would like to add a powered roof mounted fan also to give that new air somewhere to exhaust. I am looking at adding 6″ pvc vent covers over 6″ holes cut into my soffits. How many would I need? I am guessing with 10.3 sq inches of free air per vent I would need about 10 vents? Does that sound about right? I think I like the look of individual round vents over a few large rectangular vents. These are what I am looking to install. http://m.homedepot.com/p/Speed.....202907302/

    • Ed says:

      You’re going about this the wrong way. If your goal is to get your home cooler and help the A/C run efficiently so it’s able to cool the home, then attic ventilation is not where you start. Bottom line: you need a radiant barrier up there to BLOCK the heat from getting in to the attic in the first place. You can flow air through the attic (ventilation) all day long and it is not going to change the fact that you’re absorbing 100% of the radiant heat from the sun into your roof and ultimately your home. Start with this article: How Radiant Barrier Works
      Then, take a look at this video where I describe the difference between AIR temps and SURFACE temps and why it matters in making your home cooler: Difference between AIR temps & SURFACE temps in your attic & which makes the home cooler.
      If you still have questions after that, give us a call.

  94. Tony says:

    My home was built in 1889 (Southern California). The house is about 1700 square feet. I just had a new roof installed, and the roofer installed a ridge vent. There are no soffits at all, only a dormer (window) that faces the east. The attic is the blueprint for Hades! What’s the best way to cool it down? Thank you for your time.

    Tony

    • Ed says:

      I assume you’re trying to cool the attic down because you want the HOME to get cooler. Right? (Really, that’s the primary reason to cool an attic anyway.) That being said, the most effective thing you can do is to BLOCK heat from ever getting in to the attic space. To do that, you need to add a radiant barrier in your attic, stapled to the rafters preferably. The AIR temperature of the air in the attic space (which is largely determined by ventilation), is what the ventilation addresses. Air temps aren’t going to really affect the space below the attic, so the most important task is to get the surface temps low so they don’t radiate heat down into the living/cooled space. For more information on air temperature versus surface temperature, please look at this page: How Much Cooler Should My Attic Be After I Install a Radiant Barrier?
      Then, you can always add more ventilation (soffits would be a good starting point) if you want to further drop the air temp; however the radiant barrier is going to be the biggest impact for this space overall.

  95. Allan says:

    Ed, great website. Thanks for the info on the radiant barrier under asphalt shingles…makes sense. I am having my home,1350 sq. ft, reroofed with asphalt shingles. I am going with white shingles for the solar reflectivity. Currently my attic ventilation consists of two solor powered vent fans, and a gable vent at each end. There are 12 – 2″ X 10″ soffet vents, so I see that I need more soffet vents. Roofers are quoting me roofs with a continuous ridge vent and one indicated I need more soffet vents and the other said I didn’t. So the questions are, with adequate soffet ventilation which is better a continuous ridge vent, or a couple of turbine vents? Do white shingle make that much difference in attic temps? Thank you, Allan

    • Ed says:

      If you have gable vents then you probably have enough ridge for ridge vent. Just make sure you go with a high profile baffled type ridge vent. However, it does sound like too little soffit vents – I’d recommend looking in to adding more, or at least make sure they are clean and open.

      White roofs are typically about 10-20 degrees cooler than dark roofs. See attached thermal images on same day.
      White roof thermal imaging This the white roof.
      charcol roof thermal imaging This is the charcoal colored roof.
      From experience, I think this only makes a marginal difference in heat transfer into the home. But I would not do it unless you LOVE the look of white roof. Installing a radiant barrier will make a bigger impact than any white roof. More info on this page: http://www.atticfoil.com/insta.....tures.html

      Ed

  96. Tammy says:

    I just purchased a condo and one of the bedroom closets has the attic door in it. When I leave my closet door closed, it sweats extremely bad (damp clothes & door is soaked with moisture).. Any advise to correct this?

    • Ed Fritz says:

      It’s actually pretty simple. When relatively warm-moist air (in your attic) comes in contact with a “cold” surface, (in this case your uninsulated closet door – Cold can mean cool from the air conditioning) you get condensation. You need to bulk up the insulation on the door, seal it better and this should fix the moisture problem. You probably have an AC duct in the closet. When you close the door, the air probably being “pushed” into the attic around the attic door. This will cause the trim to get “cold” and sweat too.

  97. Susan Jordan says:

    My question is this. I have a 3,000 square foot new home with soffit vents all around the eaves and a ridge vent on the top of the roof. 2 of my a/c vents inside are dripping water from the attic. When the a/c repairman came out, he said our ridge vent never had the felt cut so we have a vent but it has felt so you can not see the outside. The a/c repair people want to build scaffolding inside the attic to get up there to cut the felt at GREAT expense to us. My husband wants to get on the roof and cut through it that way.

    What do you suggest to do to fix this problem?

    Sue from the very hot Louisiana South

    • Ed says:

      Sue,
      If it’s a new home, it should still be under warranty. I would start there or contact the builder.
      Otherwise you can probably have a handyman do this for cheaper than the a/c repair man is quoting. It can be done from the top outside, but it will require removing the ridge vent, cutting the felt and it will probably also require new shingles in the ridge area since most likely the existing ones will get torn up when you take off the current ridge vent.

  98. […] talked about attic ventilation issues before, in fact it’s probably one of the most popular posts on the blog to date. In that […]

  99. Kim says:

    Hi Ed,

    I have a 15-year-old roof that the shingles are literally falling off of (they are coming off in small pieces). I have been told different things by all the different contractors I have had out to look at the roof (1) wind damage (2) roof shingles were baked due to improper ventalation (3) poor quality shingles (made by IKO). I have a ridge vent with soffits. I have also been given various scenarios at varying prices to fix the roof one contractor told me my baffles are damaged and two others said the baffles are fine but my ridge vent is blocked. Help! Any ideas?

    Thanks,
    Kim

    • Ed says:

      It’s impossible for me to guess since I haven’t seen it firsthand and it’s likely that all 3 reasons have contributed to the deterioration of the roof, not to mention just normal wear-and-tear over 15 years. Keep it simple when you replace the roof: open/clean soffits for intake, open/clean exhaust – ridge vent is fine.

  100. John says:

    Hi, I have a question for you. We live in an old two-story farmhouse. Several years ago we put a ridge vent in our roof and also put in soffit vents. At the same time we also put in soffit vents under our porches because why not, right? Now here’s the rub- over time our house has become a nightmare to keep warm in the winter and I’m of the opinion that the porch soffit vents are largely to blame. The porches butt up against the house on all sides with nothing between the porch roof and the first floor ceiling/second story floors. The floors are old tongue in groove wood that have plenty of gaps, cracks, etc. for the cold air to move freely from the porch soffits through the very bones of our house. The kitchen ceiling is the same way with tongue in groove wood.

    I’ve expressed my concern several times to my father but he doesn’t seem to pay any attention. He said he asked someone who did insulation about the issue and the insulation person told him it wasn’t a problem, but I’m thinking they might have just been thinking of soffit/ridge vents on the roof of a house which aren’t as big of a deal since there is insulation in the ceiling. This to me is completely different than cold air running freely through the middle floors/ceilings of a house. IMO the situation could be largely attenuated by simply covering up the porch soffit vents with some sort of plywood during the winter but I’m disabled and again, my father doesn’t think it’s necessary.

    Do you have any advice on what should be done? Thanks a bunch for any help.

    • Ed says:

      Air should never be running through the walls/floors. I think they should call an insulation company and at least get a free estimate and have the company explain what they propose doing. Then, at least you would know the options you have and if you have the option to DIY.

  101. Kumar says:

    My attic is humid and causing mold problem. Attic is 1500 squire ft. have adequate eves Roof is not having ridge vent instead have canister vent(7) and powered attic fan that runs at Humidity control and temp control. Is this proper installation or what I should do to control the humidity in the attic to prevent mold.

    • Ed says:

      First you need to figure out where the warm moist air is leaking from. If it’s from inside the house, you need to address that and seal it up/vent it properly. Second, mildew forms because of moisture that can’t dry out – this means you probably do not, in fact, have adequate ventilation in the attic and you need to address that as well.

  102. […] Attic Ventilation Basics – Don’t Mess It Up | The Radiant … – Simple tips on Attic Ventilation can save hundreds on your energy costs. Get the right amount of air flow with the right techniques to make your home… […]

  103. Doug says:

    Hi Ed,

    Great article. I’m in the middle of doing my own roof, and would appreciate your input.

    Simple roof 12.75 squares including the garage. House alone, I’ve got 9.6 sq. at a 2.5/12 pitch. 50 year old house has 2 gable vents 1 ft sq, no soffit vent of any kind.

    I’ve got a 24 in whole house fan that is a works well in San Diego. The fan requires 6 square feet net ventilation. To that end, I’ve put in 6 Ohagin vents low on the roof (3 sq ft of intake) and next plan to add an equivalent (3 sq ft of exhaust) of ridge vent (may decrease the ridge vent to account for the existing gable vents)

    Any glaring issues with this plan?

    Few roofers in the area seem to vent anything, except maybe a turbine over the garage, so I feel like I’m “over thinking” this.

    Thx,

    –Doug

    • Ed Fritz says:

      Doug, yes if the fan requires 6 sq feet of NFA, then you will want to have at least that much in the attic. Otherwise, the added static pressure could cause the motor to burn out and you could end up driving attic air back into the home causing dust and other issues. I would bump it up some just to be sure. Remember the size of the hole and the NFA (net free area) are not the same.

  104. […] as warm air flows freely through this vented dead-air space, then upwards and out through the attic ventilation […]

  105. Several years ago my roofer insisted on replacing 13 perfectly functioning soffit vents on our roof. I immediately noticed the attic fan wouldn’t exhaust properly and told him but he insisted I was wrong. The fan no longer draws air from the open windows in the summer like it used to…in fact almost no air flow. I know it’s not the fan because when I opened the crawl space attic entrance in the bedroom closet, the air rushed out those bedroom windows and air flowed throughout the house as it used to. Conclusion, the roofer ruined our ventilation but he’s on the board of directors of the Better Business Bureau so I have no recourse. Wish we had our old vents back! What can we do to get vents with higher output like we had? Please HELP??

    • Ed Fritz says:

      I’m assuming you are referring to a “whole house” fan and not an attic fan. A whole house fan is in the ceiling of the living space and blows air INTO the attic from the open windows. Since the fan is blowing air INTO the attic, it needs “holes” in the attic for the air to be pushed out to the outside. If the soffit vents were replaced with vents that offer less open area, then it could restrict air movement. The answer is to put more “holes” in your attic. The easiest way would be to install a couple of wind turbines or static vents in the top of your attic. Assuming you have some type of exhaust vents, in the top of your attic, probably more of the same type would fix the problem. Not sure on the type/brand etc. on the soffit vents, but more or different vents with more open area could/would help. It’s really just about having more holes for the air to get out of the attic.

  106. Steve says:

    So much info here but my question is: my attic never had sofet openings and when our house was reroofed, the contractor removed an electric fan/turbine that I believe was non op? He installed 2 static vents. I installed an electric gable fan on one end that runs a majority of the hot summer days. The other gable vent needs cleaning of dust I know! I started installing sofet openings around my house but haven’t finished. Do I actually benefit from using the gable fan and if so, once I install the radiant barrier would I need it all? My sofet openings are (2) 2″ holes every other rafter opening. Think I need more?

    • Ed says:

      If you already have passive vents in your attic – you should not add an active (powered) vent to the system. Typically mixing exhaust vents is problematic to attic ventilation and AIR temp inside the attic because the strongest vent will dominate and the other exhaust vents will probably become INTAKE vents. This short-circuits the whole concept of air coming in the bottom and out the top. For more information on ventilation and mixing vents, please check out this article on Basic Ventilation Tips.
      It’s also worth mentioning that while having proper attic ventilation is important, it has nothing to do with stopping radiant heat, so you would probably benefit from a radiant barrier. The primary goal with proper ventilation is to move air and by doing so, you reduce air temperatures in the attic. However, moving air in effort to lower air temps will not really affect the surface temps of the items in the attic, and that is important because the surface temps of those items (insulation, storage, duct work, etc.) can determine how much heat is sent down, into the living/cooled space. Read more information on attic air temperature versus attic surface temperature here.

  107. Jim says:

    My hip roof is 14′ high at the middle peak. My Radiant Barrier installer is going to staple to the rafters but then cut across at 9′ high since it’s too hard to get the barrier up to the 14′ peak inside the attic.

    Is this acceptable?

    Thank you!

  108. Thomas says:

    Hi Ed. I have someone coming to install radiant barrier in my attic. I have Ridge Vents. But, there are also passive vents on the back side roof of the house. My assumption is that when the new “roof” (replaced shingles) was added (two years ago – just before I bought the house), they added the ridge vent, which likely weren’t there originally. So, are the passive vent now useless – or even worse than useless (by now acting as “intakes” rendering my soffit vent useless? Should I block those other passive vents, leaving only the soffit vents and the ridge vents?

    Also, the contractor coming (tomorrow) to install the radiant barrier (“RB”) is telling me that every edge (joint) of the RB needs to be taped. Is that true? He also is telling me that he is going to use the “flat-top” method, but he is NOT going to cut holes in the “flat top. I have never heard of this before, and everything I have seen on various websites is that you need to leave a gap at the top, or if using the “flat top” method, you need to cut holes in the “flat-top” to allow for proper ventilation of the inside of the attic (and not just allow the soffit vents vent the air directly to the ridge vents. What are your thoughts?

    • Ed says:

      A ridge vent is passive, so it’s not going to conflict with other static/passive vents on the roof.
      About the radiant barrier install – you are correct, the foil should be installed as if it were not even there in terms of airflow. Blocking airflow is a mistake and can have dramatic repercussions; being as you are the paying customer, you should make it clear to the installer that this is what you want. If he has questions, have him call us at AtticFoil and we’ll explain it to him.

  109. Thomas says:

    Ed, Thanks. If you would, would you please let me know what the repercussions of blocking the airflow would be? That really concerns me.

    He keeps telling me it wouldn’t matter b/c the airflow is going from the soffit vents to the ridge vent on the other side (i.e., the roof side) of the radiant barrier and that there is no need to have the “inside” of the attic (i.e., the space on the “inside” of the radiant barrier) getting any venting. In fact, he keeps telling me (when I tell him what I’ve read online) that every one is doing it wrong b/c if you add the openings at the top of the “flat top” the hot air will simply spill back into the “inside” space of the attic.

    Thanks,
    Thomas

    • Ed says:

      Blocking/prohibiting air flow can impede moisture drying out and moisture that sticks around can turn into mold/mildew. As it stands right now (with no radiant barrier) air from the soffits is entering the entire attic space, it’s not just staying along the roof deck. So, when you add the foil, you do so in a way that doesn’t change how things are now/pre-foil. This means leaving gaps around the install so air can move on ALL sides of the foil, like it currently does. Disrupting this air flow from the normal pattern is what can lead to moisture build-up and other issues. Does that make sense? If it’s not broken now, why would you change it? This page includes 2 videos that go into more depth on this: Radiant Barrier & Attic Ventilation
      Remember, YOU are the paying customer so YOU decide what the hired person is going to do.

  110. Jim says:

    I am replacing a wood shake roof with asphalt shingle. My roof is gabled and steep, 12;12. I have two gable vents and 5 pan vents. My roofer is suggesting replacing the pan vents with ridge venting. Would this be an improvement? Would I need to cover the gabled vents? Not sure why the gable vents would function differently if go from pan to ridge? Or maybe they should have been covered all along. I forgot to mention that the gable vents are in the front of the house and the pan vents are on the back side of the roof and house, if that makes a difference.

    • Ed says:

      Some would say ridge vents are an improvement over pan vents because they sit at the highest part of the roof and exhaust the best. It’s hard to say in your case if that is true; what is the reason for replacing them/why are you changing the ventilation? The gables should be ok – all vents are passive so they shouldn’t dramatically interfere with one another.

  111. Geoff says:

    My attic area is approx. 1150 sq. ft. I have one 10″ turbine in the center top of the roof and two gable vents approx. 1 sq. ft each. I will be drilling 45- 3″ holes in each of the 2 soffits and covering the holes with continuous 8 ft. White Under Eave Aluminum Soffit Vents. I have fiberglass batts in the attic and will also be installing a radiant barrier under the roof. My question is – do I need baffles ( or should I just make sure there is a small gap over the soffit vents) and if so, should the baffles be positioned below or above the radiant barrier.
    Thanks

    • Ed says:

      As long as the insulation doesn’t cover the soffits and they are able to bring air in both behind the foil (between foil and roof) AND in front of the foil (ie. the main attic space), then you can omit using baffles.

  112. I have a 2200 ft home with 7/12 pitch, only have ridge cap and 2 gable vents. Attic is extremely hot, Do I need to install soffit vents to get more air flow.

    Regards
    Howard

    • Ed says:

      If you don’t have any soffit vents then yes, you should add some venting down near the bottom of the attic (by the eaves) as your INTAKE venting system.

  113. Jon says:

    Great stuff, great concepts.

    Scenario- 1895 house Rennovation. Very drafty house. Basement/house moisture controlled, attic batt insulation removed and to be replaced with spray foam on attic floor/2nd floor ceiling. New asphalt roof — definitely will place a radiant barrier on the underside of rafters. Soffit vents (2″ holes) are a joke and will likely be consumed by spray foam in this balloon frame house. Ridge vent is present but can be removed with new roof. I question whether attic ventilation will be needed for this scenario.

    Perhaps not technically a conditioned space, drafts from the main living area will be virtually eliminated. Radiant barrier should drastically reduce heat gain in attic due to shingles, correct? Is there any reason to keep , say ridge venting strictly for the purpose of allowing radiant heat to escape upwards, or will it conduct back through the sheathing and shingles? My thoughts are to eliminate all venting in attic, especially because I will have a SpacePak system for heating and A/C up there, for 2nd floor.

    Thanks!

    • Ed says:

      At this point, I would say you should probably skip foaming the floor and just do the roofline; go for a fully sealed/non vented attic space.

  114. Jason says:

    I have one roofer who wants to put in 3 turbine vents; the other wants to put in a couple ridge vents and 4 slant back vents. Which is the better way to go? As for the soffit vents, I have noticed that the “holes” under the covers are not cut out sufficiently as they should – though I can’t seem to figure out how to remove the staples (not screws!) so I can cut the holes adequately and, of course, to see if there is any obstruction. Suggestions, please.

    • Ed says:

      Based on what you have described, I think it is best to just tear out the existing soffit covers and replace them with AirVent brand soffit vents.
      Also, I tend to favor wind turbines on higher pitch roofs, and ridge vents on lower pitch roofs. Whichever way you go, I would not recommend mixing ridge vents AND slant back vents (air hawks).

  115. Brad Bowman says:

    Building a 38×23 shop. I have a truss roof with 2×4 top cord. I am planning on full soffit and ridge venting with metal roof.I will put foil on bottom of top cord and have a 3.5″ air gap.This air gap will be the vent area of the shop. I am planning on having a wood stove for heat in the winter as the building is in Idaho. Also using Tyvek on exterior under a metal siding. Would there be an advantage to putting foil on the outside as opposed to the inside of studs? I will be insulating wall with fiberglass. If I need to insulate the ceiling I guess I could install at the flat area of trusses later? I am not planning on drywalling ceiling. The trusses will all be exposed to work area. Thank You.

    • Ed says:

      You want to get the foil closest to the exterior sheathing in order to get optimal performance for heat rejection. Also, it’s ideal when the air gap is between the heat source (or the sun in this case) and the foil – this allows the foil to REFLECT heat back out of the shop and that keeps most items cooler.

  116. myrooff says:

    thanks for pics.

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  119. chad says:

    I have ridges that are about 10 feet lower than the upper ridge… open attic.. There was a roof louver on the lower ridges.. front and back. It is my understanding that these would become intake and just pull air in there to be sucked out the louvers at the peak… There is no soffit vents in these areas of the house. only areas where there is not soffit vents.. they are gables if I were to add soffit vents would it suck air out of these lower louvers or still be an intake like the new soffit vents?

    • Ed Fritz says:

      Chad, it’s tough to say for sure where exactly the air will come in and go out. A lot has to do with the air temperature, attic temperature and mostly the wind. In general the more “holes” the better. If you CAN get some soffit vents in at the lowest part of the attic it would be best.

  120. Monika Kennedy says:

    I just had a solar company coming out and they recommended Radiant Barrier and 2 Solar Attic Fans for $ 8,145.00 for 1960 sqft house minus 30% tax credit. In the moment I have Soffit vents and roof ridge vents and the attic insulation seems to be adequate. Is that a good investment or shall I leave it like it is?

  121. Clyde says:

    Ed,
    I have a 3,000sqft attic on a total hip roof with 10 total sqft of ridge vent ventilation (22′ of ridge vent on the east side, 30′ on the north side and 8′ on the west side of the house). I have 29 soffit vents that provide about 27 total sqft of soffit ventilation. The ambient air temperature in the attic is still over 120 when it is 95 outside. Would you recommend adding 4 14″ wind turbines to get that temp down or should I go another route?

    • Ed Fritz says:

      Ridge vents come in 50 different flavors. Ranging from very effective – 18sq. Net Free Area per linear ft. to almost worthless. The high profile baffled vents are best. Why not add a Radiant Barrier? People get hung up on the air temperature, when what really matters is the INSULATION Temperature or surface temps. If you install a radiant barrier, you will drop the insulation temp and the air temp will most likely drop too.

  122. Clyde says:

    Ed thanks much for the insight. I have the GAF Cobra 3 model # 2018000 Ridge Vents that look like they have 18 sq net free area per linear ft. My attic stays close to outside ambient up to 90 degrees. Over 90 degrees it ramps up quickly to 25% warmer than outside ambient.

    Outside Avg Increase
    Tem in Attic Temp
    95 24%
    96 26%
    97 24%
    98 24%
    99 23%
    100 25%
    101 26%

    I just had additional blown in insulation added to the attic so it is sitting at about an R40+ right now. Also my ceiling temperature remains at about 79 – 80 degrees when it is 100 outside and 127 in my attic.

    Is the high temperatures in my attic a concern that I should take action to fix and if so is installing a Radiant Barrier then the most economical way to drop the temperature in the attic or is adding 4 passive 14″ external braced wind turbines?

    • Ed Fritz says:

      A radiant barrier should make a big difference. Attic ventilation is like leaving the windows open on a car parked in the sun. It will only help so much. If you REALLY want to cool down the car you want to park in the shade (radiant barrier). I would NOT add wind turbines. You do not want to mix styles of exhaust vents. Installing AtticFoil Radiant Barrier will make a big difference and you will find that the air temperature will drop dramatically below the AtticFoil and that whatever ventilation you have will be adequate.

  123. Julie says:

    I need help:) I have installed radiant barrier to attic. I have blown in cellulose insulation. I have 2 small gable vents, no soffits or lower intake vents of any kind.
    I have 1600 sq feet in attic with 7/12 pitch, no ridge cap and 2 gable vents octagon shape. Attic is extremely hot after installing radiant barrier. Do I need more ventilation? What size gable vents should I have?
    I have an attic fan that I was going to install on gable?
    Thanks for your advice!
    Julie

    • Ed Fritz says:

      Julie, You really need some bottom side air vents. Hot air does not actually rise. It is LIFTED by cooler(denser) air. Putting a few soffit vents or lower intake vents will make a huge difference. Cooler air will come in an PUSH the hot air out the gable vents.

  124. Jerry says:

    Hi Ed,

    I’ve got an older house we’re doing work on with the original clay roof tiles. Looks like they’ve painted a coating on the clay tile that resembles ceramic look. There is no ventilation. I’m thinking radiant barrier on the underneath side of rafters. Thinking about how to best defuse the radiant heat buildup in the air barrier between radiant barrier and rafter cavity (2×6). One thought is gable vents…thx

  125. ngoc ho says:

    Hi,

    My house is 2047 sq feet & has a ridge vent on the top of the house and also 3 plstic air hawk vents, two of which are leaking. One of the contractors told me that I do not need to have those 3 air hawk vents since I have a ridge vent. Should I close them up with decking or replace air hawk vents with the metal ones like lomanco aluminum? Is one ridge vent enough for my house?

  126. Gulliver Viray says:

    Ed,

    I have an 1100sqfoot home. 3 soffits in the front of the house and 5 soffits in the rear (though 3 of the 5 are partially blocked because of the sunroom the previous homeowner installed. Any air pulled in these 3 are heated up by the sunroom roof). There are also 2 gable vents on the sides of the house (one on each side). As far as exhaust, I have 3 eyebrow vents placed equidistant from each other.

    I had planned on replacing the center eyebrow vent with a solar attic fan that is rated for 2400sqft (with electric mode for evenings until the temp reaches a specific temp). The install instructions tell me to block the 2 other eyebrow vents. Do I also block the 2 side gable vents? That way the only source of intake would be the soffits.

    Along with this, I also plan on installing the attic foil on the rafters (due to ductwork in the attic).

    • Ed Fritz says:

      If it were my home I would not do anything with the ventilation until after I install the radiant barrier. What most people find is that the radiant barrier cools the attic and insulation so much that whatever ventilation they have is usually adequate. Once the foil is installed, measure the AIR below the foil. If it’s MORE than about 10-15 degrees above ambient then that tells you your ventilation needs work. At that point I would do it only if needed. If you do install the fan, I’d leave the far gable vents open unless you can add more soffit vents. 5 soffit vents are not enough to handle that big of a fan.

  127. Jeff says:

    I have unfinished upstairs. I am not sure where to put radiant barrier rolls. Should I put radiant barrier rolls to the attic plywood, then Owens Corning Rafters Vent, then insulation (R38-unfaced) then sheetrock or wood panels?

    Or Radiant Barrier between the insulation (R38-faced) and sheetrock/wood panels.

    Lastly, I was not sure whether I should use faced or unfaced insulation in either way. Thanks in advance for your assistance.

    -Jeff

    • Ed Fritz says:

      Jeff, If you are doing a cathedral ceiling, you will probably want to install the Radiant Barrier Foil between the roof deck and the insulation. You must have an an airspace!! The layers from the outside would be: Roof Deck> Air Space made from foam strips> Radiant barrier Foil > Traditional insulation > Inside cladding, sheetrock, tongue and groove etc. Here are the instructions on How To Install Radiant Barrier In An Unfinished Attic

  128. Adam says:

    I live in a bungalow style home that currently has two big gable vents and two pan vents toward the ridge. I’m getting it re-roofed and the contractor said that the gable vents should be sufficient ventilation (there’s no type of soffit intake on this 1930’s house) and their plan is to remove the old pan vents. Does that sound right?

    • Ed says:

      Not exactly. Ventilation intake should really be lower down near the floor of the attic so it creates the loop I mentioned in this article. Without intake, you’re not really going to have a lot of air flow throughout the attic. If you choose to vent the roof deck, then you have to be serious about it and really vent it. You need an airtight ceiling, lots of air flow, plenty of soffit vents, and deep insulation at the attic perimeter to do it right.

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