Attic & Foam Insulation

Ask Your Question

Email: 1

1 - Notification of when your question has been answered. (Optional)

View Questions

  1. Rating: +0

    Positive Negative

    Hi there, I am just about to re-roof due to hail damage and my roofer has recommended a solar shield material to go under the one area of my roof where I see a large rectangular frost patch on cold mornings (this is above the cathedral ceilings). Though not functioning as a radient barrier will this help prevent the heat from seeping out. Is it safe for the shingles? Is it worth the extra expense? Thank you for you help.

    I'd do nothing and not spend the extra money. You actually want a "cold" roof in the winter. It means you have decent attic ventilation and will help prevent potential ice damming.
    Frost on a roof is not a bad thing on a cold morning. This tells me that the area over the cathedral ceiling is staying cold and NOT loosing much heat. I would be more concerned if the area was NOT frosted. Without frost, it would mean the area was loosing heat and the surface temperature was above freezing. Often, you will see a roof with "strips" of frost. This clearly shows where the cathedral ceilings are located. By having frost, this part of the roof is keeping the heat from escaping. Areas without frost are usually over the attic part and are not frosted since heat from the house is escaping into the attic and heating up the roof. Frost won't happen unless the surface is below freezing.

  2. Rating: +0

    Positive Negative

    Ed - would it be efficient to not only put foil on my roof rafters, but also over my insulation on the attic floor? -Kent

    I've had many customers install AtticFoil in both locations with exceptional results. If you can do it as a DIY project and keep the cost down, then I would say "Do It!"
    If you lay the AtticFoil over the insulation in addition to stapling it to the rafters, you will see the biggest benefit in reducing winter heat loss. Be sure to read the warnings here: about sealing up the ceiling to prevent warm-moist air from passing through the ceiling and insulation and possibly getting trapped under the AtticFoil. AtticFoil IS a perforated radiant barrier, so it can handle the "regular" amount of moisture that naturally passes through the sheetrock and insulation, but it could be overloaded if you have a large source of warm moisture laden air.

  3. Rating: +0

    Positive Negative

    I live outside Phoenix, AZ and I have a flat roof that will be redone (no attic). Can I create a sandwich of plywood decking with foam spacers and then have a spray foam insulation installed on top?

    You COULD do this. However, I think it would be a LOT of work for limited extra benefit. If you have a flat roof, consider a product like instead. One of the great features of a roof like this is that you could easily overlay 2-4 inches of dense ISO Board (PolyISOcyanurate), then put the Duro-Last roof on top. Products like Duro-Last are known as "cool roofs." For example, you can walk barefoot on a Duro-Last roof on a hot sunny day. By COMBINING the foam board (R-value) with the reflectivity of the white membrane roof, you will SAVE a bundle on cooling expenses AND have an awesome quality leak-proof roof to boot.

  4. Rating: +0

    Positive Negative

    I have a flat roof in rowhome in Philadelphia. I'm in the middle of the block. My joists run parallel to the front/back walls, so there's no way I can vent. I need both a radiant barrier and insulation. Does the air space need to actually vent anywhere? Could I put up the foil with an air gap and then put fiberglass below? Fortunately I have full access to the underside of the roof deck. Thanks! Mike

    Having sealed, or "dead air", is ok. In the Cathedral Ceiling installation method the air inside the assembly is not vented, but there is no risk or damage from "holding" the hot air in the wall. Just keep in mind that the total assembly will probably be a little warmer since it does not have the ability to vent some of the heat. Luckily, 97% of that heat will be reflected, so you're only talking about dealing with about 3% of the heat anyway.

    Have you had a chance to take a look at the video: How to Install Radiant Barrier in a Cathedral Ceiling? It's the third video on the page and it explains how you can get both a radiant barrier AND traditional insulation in the wall assembly for maximum benefit.

  5. Rating: +0

    Positive Negative

    We have a multi-level flat roof house with standard roofing material. Several rooms are VERY HOT (the same temp as outside or even hotter) despite using window tinting, solar shades and drapes. We live in Sedona, AZ where in the summer it will be in the mid-high 90's at it's worst and drop down to the 70's at night. The MBR is a particular problem at the highest point of the house. It's well over 85 in there even when it is only 80 outside. We have been told that is we "foamed" the roof using either R-7 or R-14 we would see a huge decrease in this heat issue and perhaps cut our very high electric bills in 1/2. The foam (depending on R-7 or R-14 and if we do the whole house or only certain rooms) was quoted at basically $2 a square foot. If it paid for itself in a couple of years or less then that would be fine. So thoughts? Is it worth doing this? We can't insulate anywhere else as there is only a crawl space available since it is flat roof (and there is the standard pink insulation in there, I saw it when I had to take down a ceiling speaker). Thanks!

    I'd need more information to properly address this situation. What about the A/C system? Based on what you have mentioned, it appears that you might be better off just adding insulation when you replace the roof - a product like Duro-Last would be a good choice.

  6. Rating: +2

    Positive Negative

    I have a almost flat roof with no attic. Just the 4x6 beams then the ceiling and roof. How do I best improve insulation?

    The downside is that there is no easy/simple way to add radiant barrier to a finished cathedral ceiling. The good news is that you do have a few options:

    First, you could remove the sheetrock and install radiant barrier foil via the Cathedral Ceiling Method. This can be labor intensive and costly, but this would garner the best results.

    Essentially your layers will be as so, coming from the roof down:
    Roof deck
    Air Space
    Radiant Barrier Foil

    Or, another option is to install radiant barrier foil over the existing sheetrock, but then you have to create an airspace. The best way to do this would be to use wooden battens over the existing layer of sheetrock and then staple the foil to the battens and then install new sheetrock over it. If you wanted to keep it simple, you could just bulk up what existing insulation you have. I recommend you get 3/4" to 1.5" foam board and apply it directly over the existing ceiling and the drywall over the foam board.

  7. Rating: +0

    Positive Negative

    Hi - We are building our entire home without any attic space. We have already bought one sided radiant OSB, 4cm polystyrene insulation, plasterboard, asphalt felting and shingles! The roof structure is of galvanized metal. What is the best way to construct our roof - we are in hot climate. Thanks for your advice.

    You will build this roof like any other. Just make sure your Techshield (foil-faced OSB) is installed so the radiant barrier is facing DOWN, toward the open attic space below the rafters. After that you build the rood out as normal. The ONLY reason you would need insulation up on the roof line is if you were not actually going to keep the attic, but instead were going to convert it to living space that you heat and cool. Otherwise, insulation does NOT belong on the roofline.

    If you are converting the attic space into living space that will be heated and cooled, then you will add insulation via the Cathedral Ceiling Method; essentially since you have foil on the deck already, your layers will look like this coming down into the space:
    Roof deck with Radiant Barrier Foil layer facing into attic
    Air Space

  8. Rating: +0

    Positive Negative

    I have an uninsulated vaulted ceiling that I want to use your product and rigid foam due to the 3" rafters (22" on Center). I need to know where I need the air spaces. I want to use 2" Foam board so that will leave me with 2 - 1/2" spaces. Your video says to have 1/2" air gap betwwen the roof and foil and then do I need an air gap between the foil and Foam Board? What about between the rigid foam and the drywall?? Thanks, Lisa in Lebec (CA) PS what would the total R Value be after I put all these products together? (My roof is made with true 3" rafters, 1x12's ran perpendicular to the rafters, Tar paper and composite shingles.)(in laywomen's terms)

    You have it right - you need a space between the roof and the foil, but you do NOT need another gap between the foil and the foam board, nor do you need a gap between the foam and drywall. Honestly, if it were me, I would utilize the entire inch of space between the foil and the roof deck.

    As far as the R-value, you would need to determine that based on what materials you use and in what quantities. Radiant barrier has no R-value, so it will not factor into this equation.

  9. Rating: +0

    Positive Negative

    Hello, My 30year old home, A/C heat is in the Attic and the flue for the other one comes up through the attic also. Should I Go with Foam or a Radiant barrier? Due to the Carbon monoxide leak if was to happen? the house also has a attic fan in it.

    Foam is going to slow down conductive heat loss/gain and foil is going to stop 97% of RADIANT heat gain; one does not replace the other.
    In my home I have BOTH - foam AND radiant barrier.

  10. Rating: +0

    Positive Negative

    I'm getting conflicting info from contractors and am stymied. My home was built in 1960 and has a 4/12 pitched roof. We are adding an addition with a 9/12 roof and will be installing decking and new shingles for new and old portions. I planned to have Icynene foam sprayed in walls of the addition and have cellulose sprayed in the entire attic (and remove the old insulation as we've had mice) but had a spray foam contractor say I should spray the entire attic and if I need to save $$ use foam insulation in the new walls. We installed a HE HVAC system already (sized for the house with the addition) so reducing the tonnage is not an option. Should I follow my original plan? Or use radiant barrior or sprayed open cell foam on the underside of roof?

    I think the only time you should foam the deck is if you are doing new construction and doing a fully encapsulated "non-vented" attic. Otherwise, stick with the proven combination of traditional insulation (blown-in cellulose is fine) and a radiant barrier. Combine those with some decent attic ventilation and you'll have a system that works great.

  11. Rating: +0

    Positive Negative

    I purchased rolled R-13 insullation to put in my attic over the flooring which already has insulation in it. I asked and was told that the paper side of the insulation was to be up - away from the floor not against the floor. Last night I had an e-shield sales person look at my attic and told me that the paper side of the insulation should be down against the floor in the attic. When I purchased the insulationat lowe's I was told that paper side goes up. I am an 68 yr old female senior. i am now thoroughly confused. Do I leave the paper side of insulation up toward the ceiling or do I go up into the attic and flip the insulatin so that the paper side is down toward the house. Plesae help. I am now also trying to see if I would be smart to put in the radient barrier. from reading you info it loos as though something called AtticFoil might be just as good and less expensive - I had been quoted a bottom price of 4600 to install e-shield

    Typically the batt insulation is laid so that the paper is down, closest to the drywall/ceiling of the floor below the attic.
    As far as adding a radiant barrier, while radiant barrier is NOT a substitution for traditional insulation, it does work very well WITH traditional insulation to make it more effective. The combination of the two (regular insulation and radiant barrier) works to keep the home more comfortable and energy efficient, year round. EShield sells (and installs) a product that has a tiny layer of insulation in between the two foil layers, but it is really irrelevant since a person already has traditional insulation on their attic floor! What works about that product is the FOIL, not the small layer of insulation. Take a look at for some more information and perhaps you can even find a radiant barrier installer in your area who could help you install a radiant barrier.

  12. Rating: +0

    Positive Negative

    I would like to install composition shingles over underlayment over "Techshield" OSB with sprayed Iceynene closed cell foam applied to underside of the Techshield deck. Without an airspace, does this defeat the purpose of the radiant barrier and result in a "hot" roof which might degrade or damage the insulation? Would open cell foam be better?

    Yes, a radiant barrier does not work without an air space and so when it is sandwiched between other layers, the heat flows conductively and aluminum is a great conductor of heat, meaning it will PROMOTE heat transfer instead of preventing it. The only way any radiant barrier will work is if radiant heat is present, and radiant heat can only exist in an air space/vacuum.

    The best set up is a combination of both a radiant barrier and traditional insulation (or spray foam insulation), since the two products address two different forms of heat.

  13. Rating: +1

    Positive Negative

    Two questions first one is in a typically cold climate like North Dakotawhat kind of savings can be seen with a radiant barrier added to let's say R 16 bat in a percentage how much of a percent of my heating bill will be saved . Cold climate . . 2nd is it possible that adding a reflective insulation that is breathable or a radiant barrier could casue damage to areas where cieling is taped and mudded because the heat is being pressed down . . Being that there is no dead air between the insulation and the radiant barrier . That's my questions thanks a lot

    1. There is no truthful way to tell you what kind of savings you will get because (1) every home is different and (2) energy savings amount to a whole lot of factors besides just adding a radiant barrier. I don't offer false promises; the more roof area that catches sun and you are able to cover below that, the bigger the impact.
    2. No, radiant barrier will not cause damage to roof shingles because radiant barrier does not change the AMOUNT of heat, just the DIRECTION it travels. It's like a lamp without a shade. It puts out light in a room, but if you add a lampshade to it the light now travels in different directions, you haven't change the amount of light, just where it travels.

  14. Rating: +0

    Positive Negative

    i have no storage space, only a very small section of the attic over the garage. however the attic is huge but has so many wood support for the roof all over unable to move. can this problem be fixed o allow storage by removing or restructure the support?

    You need to talk to an engineer or architect before messing with any supports - they are there for a reason.

  15. Rating: +0

    Positive Negative

    I have a 2500 sq. ft. bungalow in Dallas, Texas. There are seven inches of foam insulation in the attic with an R14 rating. A local company is saying that I need 19 inches for an R50 rating. Due to cost considerations, I looked at an additional five inches for a total of 12 inches and a R30 rating. The contractor who services the A/C-heating has always checked the insulation and found it adequate. Do I need the additional insulation? Tanks for your help. Peter

    It's hard for me to say since I haven't been in your attic or seen what the current insulation looks like. The US Department of Energy has recommended guidelines for insulation levels based on geography in the US.
    Take a look at that. Otherwise, you could also get a second opinion from another insulation contractor.

  16. Rating: +0

    Positive Negative

    In the fall and springtime in Dallas, it is often warmer than comfortable in the daytime, and refreshingly cool at night. With an encapsulated attic, warm air from the living areas accumulates in the attic all day, and there is no way for it to escape. The solution seems to be a switch-operated or temperature-automated insulated damper or door, with perhaps a fan, at the top of a gable, or on the roof at the peak. That, combined with open windows on the ground floor would create that ideal stack effect, evacuating the accumulated heat, while drawing in the cool nighttime air. The house would quickly become nice and cool, and insulation and thermal mass would keep the house pretty cool all the next day. Have you found a product that would accomplish this? The closest I have found is this: but it is pretty expensive, and I don't think the fan would be necessary. Another issue is fire code. For the system to work, the ceiling would have to be penetrated. To be code compliant, you'd need a fire-rated louver or damper at the ceiling, that opened at the same time as the damper to the outside air, and closed when smoke was detected. Got any design ideas?

    Considering there are only a few weeks a year where this would be an advantage I don't think I would install anything. On cool nights, we crack/open our windows and run the bathroom fans and kitchen vent hood to pull cool air in.

    Another option (If you have the air handler in the attic) is to open the filter door and it will act as a return air vent that will pull air out of the attic. Depending on how tight your ceiling is, you might need to leave a door open to the attic to give the make up air a path.

  17. Rating: +0

    Positive Negative

    I've recently seen some homes that used Tech Shield sheathing on the roof. They claimed that it would reduce hvac load in the summer and winter. The problem is that I don't see how it's possible for the foil to help during summer months because there is no air gap between the foil and the roof shingles. Diffusion of heat will basically be the same as without the foil on the underside of the sheathing. I can see some benifits in cold climates where you reflect heat back into the house, but see no benifits from summer heating. Am I missing something?

    The air gap only needs to be on one side of the foil barrier for it to work. In the case of Tech Shield the air gap is the attic side air - it DOES work. However, the one downside to it is that the rafters are not covered in this application, so they can still bridge heat from the roof into the attic. That aside, the majority of the roofline is still covered so the results are pretty good.

  18. Rating: +2

    Positive Negative

    i have an overlay of pink faced insulation should i take it out and then blow in new insulation and put the pink back down or should i blow the new insulation over the pink faced insulation

    If they are unfaced batts of insulation (meaning there is a pink side facing up into the attic), I don't see a problem with blowing in cellulose over the existing insulation.

  19. Rating: +0

    Positive Negative

    I live in Birmingham, AL, have a 1-12 pitched roof with ridge-vents,vaulted interior ceiings. My Insulation in the attic is r-25: 1-Will a radiant barrier help? If so, how mucm? 2-Should I cover soffit to ridge-vents and also lay blanket of film over batt/and blown insulation in attic? Thank you for you advice.

    Does radiant barrier work? Yes, it is proven science, it works. The question people often hope to address when they ask this question is typically how much can they expect to save?  If this is what you are wondering, I have to be honest: it can be hard to quantify since every home is different but in general the more space you have in direct sunlight that you are able to cover with a radiant barrier, the more you stand to gain by adding one.  Check out this article on Expected Savings with Radiant Barrier Foil.

    As far as doing both methods - I have seen this becoming more and more popular.  While only one layer of application is necessary to get 97% heat block, many people are opting to do both methods to see the best results year round.  For more information, here is a good article: Installing radiant barrier on attic rafters and over attic insulation.

  20. Rating: +1

    Positive Negative

    hi ed my attic over my garage share the stairwell to the upstairs and the vaulted ceiling of the family room the high end the stairwell going up the stairs has warm spots on the living side of the wall they put r11 on the studs 2x4 studs and then the drywall would the radiant barrier help for this or install foam board cellotex and radiant barrier spaced away from the insulation

    If you can get the radiant barrier between the ROOF and the insulation up there, then it will offer tremendous help! See this page for more information on this application technique: How to Install Radiant Barrier in a Cathedral Ceiling.

  21. Rating: +0

    Positive Negative

    we want to put up a radiant barrier in the third floor before we finish it for living space. Were would we place the barrier, right up against the roof then put a baffle for an air space then regular insulation then drywall? Or, do we keep a space between the roof plywood, then the barrier then the baffle, then insulation and drywall?

    Ideally you would keep a space between the roof deck and the foil. This is a common installation called the Cathedral Ceiling method - it works well for converting unconditioned spaces into living spaces - see photos, a video and install tips here.

  22. Rating: +0

    Positive Negative

    Hi Ed, I've started usic Attic Foil and am pleased with it (particularly with the strength of the foil.. does not tear easily). I've already spanned my attic rafters with one piece that is 24 feet long. Just stapled it in place. My question is do you recommend using it as an insulation baffle right next to the soffit on the floor. I want to blow-in fiber glass insulation and need a baffle to keep it a safe distance from the soffit intake. There exist thin black plastic baffles (Accuvent) which I have purchased, but my rafter spacing is somewhat irregular and the baffles have irregular surfaces. So I'm thinking it might be easiest just to use attic foil for this. I realize Attic Foil does have small perforations (it's not a moisture barrier), but should it provide a good enough barrier between the environment in the soffit intake and the blown-in fiberglass on the floor? Thanks

  23. Rating: +0

    Positive Negative

    I live in Albany County, New York and we are looking to have our house insulated, including our large, walk-up attic. We would like to spray foam the roof of the attic and eventually finish the space, but we were told once we spray foam we need to sheet rock or spray a thermal barrier almost immediately, adding a significant cost to the project. The last quote we received was the only contractor who told us this was necessary so now we are concerned about the cost moving forward but our 1890 house has NO insulation in a very cold climate! Any idea if sheetrock/thermal barrier is immediately required? The attic is strictly used for storage.

    I am not sure what the building/remodeling codes in your county dictate - I would contact a local building code office to get the most accurate information. I can't imagine why this would be mandated on a non-conditioned space, but I'd check with your county to be sure of what you need to do.

  24. Rating: +0

    Positive Negative

    We just moved into a new home, and the living portion of the house has batt in the walls and open cell foam elsewhere. It's really great! Our garage is 20 x 27 and has ZERO insulation, and therefore it gets quite hot in the attic over the garage. There are no vents. Would it be more cost efficient to foam the roof (we have a 12' pitch roof) or just batt the ceiling, and would this be enough to keep the garage cool in our hot Georgia summers? Thanks so much

    For a garage, or any non-conditioned space (meaning you aren't heating and/or cooling the area), the best option is to just add a radiant barrier because there is nothing better than radiant barrier to keep it cool; basically, you are looking for shade from the HEAT. As it stands you are gaining 100% of radiant heat (that heat is coming from the sun) into that space, which you probably know since you feel it! Traditional insulation is NOT needed (or recommended) on a non-conditioned spaces like garages. Simply staple the foil to the bottom of the rafters above the garage, just like you would in an attic space.
    Installation guide is here: Radiant Barrier Staple up installation
    If the garage door or garage walls are also catching sunlight, you need to add some radiant barrier on those surfaces as well. Here is an article on: adding radiant barrier to the garage door and garage walls

  25. Rating: +0

    Positive Negative

    On a 30 yr old flat roof townhouse with no attic. From a roof leak, partial ceiling & insulation caved into upstairs bathroom. Looking up into the 18x24 hole in the ceiling, I can see plywood above the insulation. Before I replace the insulation & ceiling, should the plywood also be replaced? Would hardi-plank be appropriate?

    I'd recommend you talk to a roofing professional about this repair. From an insulation standpoint, you should consider adding radiant barrier up there while you have the roof open. The cathedral ceiling method would be the way to go over an area like this with a flat roof: cathedral ceiling method installation click here

  26. Rating: +0

    Positive Negative

    I have a house im doing work at, and the interior perrimiter walls are foam board and i bave to install my gas lines on the block wall can i cut out the foam to install lines and re silver tape back over it

    You will want to use some type of foam to seal the hole, not just tape.

  27. Rating: +0

    Positive Negative

    I have a lake cottage that has an old flat tar roof that covered the portion of the house that was not 2 stories. The flat roof rafters are 2 x 6 with 6 inch insulation and the old roofing material is a tar material about 1 inch thick. The previous owner put on a new roof (12/3 pitch) structure over the old roof, adding a 8' veranda porch. There is a 2 ft to 3.5 ft gap between the old tar roof and the new roof. Can I put insulation over or on top of the old tar roof? Will there be moisture problem? Can I use blown in insulation? If so, I was thinking going with 18 inches of blown insulation. Dave

    Yes, you can add insulation over the old roof. The better option in this case would be to add a perforated radiant barrier in combination with some traditional insulation or even foam board. Moisture should only be a problem if the area below the old roof is not air tight & therefore is leaking air into the air space. Make the old roof airtight then add your insulation and top it off with the radiant barrier foil open to at least a 3/4" air gap facing the new roof.

  28. Rating: +0

    Positive Negative

    My home is insulated with spray foam. The entire roof joist is foamed. Currently have on insulation on the attic floor, I assume that was by design. Would it be safe for me to now use blown-in cellulose on the attic floor?

    If you have a fully foam encapsulated attic then there is no need for additional insulation on the attic floor.

  29. Rating: +0

    Positive Negative

    We have a cottage that we use in the winter months. As we had no intention of using it year round when we built the insulation in the attic is only R24. We have been told that we should have foam insulation blown into the livingroom, dining room and living room areas (one big room) and that it is ok to leave the bedrooms?? What do you think.

    I think if you are going to go through the trouble, you should do the whole thing. Furthermore, if you are only using it part of the year, you'll probably have a better investment using a radiant barrier to help hold the heat inside. Radiant barrier will make the insulation you already have more effective. The best way to install it would be closest to the inside of the home:

  30. Rating: +0

    Positive Negative

    I have spray foamed the underside of the roof in the attic area. However, I am having a problem with condensation in the living space. Does the attic and the living space need to 'talk'? Right now I don't think there is any free air flow between the the attic and the living space. I literally have water on the walls.

    Sounds like you have reduced the load of the home so much that your air conditioner is too oversized and it is not running long enough to dehumidify. This can be an unintended consequence of retrofitting an existing home with a sealed foam attic. I would consult a very good air conditioning company. Generally, you have several options: Install a dehumidifier, install a "mini-split" ac system that will run at "part load" and both cool and dehumidify or replace your ac system with a smaller tonnage system.

  31. Rating: +0

    Positive Negative

    hello,i have loose fill fiberglass insulation now. im thinking of instaling spray foam between the rafters in the attic making it a non vented attic.will this shorten the life on my asfalt shingles since it has no ventilation?will i have to remove fiberglass or is this a plus?i live in deep south texas very mild winters,hot 100+ degrees from may to sept.attic is large 8"pitch with large span.

    Are you wanting to add spray foam to tackle the problem of the heat load that comes with your location? If so, your better bet would be to get a radiant barrier up on the rafters and block 97% of the heat from coming in to the attic space in the first place. One thing that often happens when foaming an existing home is that now the AC system is so oversized it can result in not removing enough moisture. The AC system will only run short period of time to remove the sensible load (heat) but does not run long enough to remove the latent load (moisture). I love foam closed attics (I have one) but usually only recommend doing it on new construction when you can properly design the AC system for it.

  32. Rating: +0

    Positive Negative

    I recently had a fire in my two year old home. The fire wasn't so bad , but the smoke completely filled the attic space. I suspect the radiant barrier was compromised. The radiant barrier is attached to the roof decking and one option is to remove the roof and replace the radiant barrier / roof. Would adding foam insulation to the roof be a good alternative solution ?

    If the foil is still shiny and sturdy, it should still work fine. Foam isn't going to perform like radiant barrier. It, just like traditional insulation, slows conductive heat gain/loss but it doesn't stop it. Radiant barrier blocks 97% of radiant heat. You can either replace the radiant barrier decking with new radiant barrier decking (quite economical) or you can add radiant barrier foil over your rafters before the roof deck is put in place. Having a radiant barrier as your first line of defense up on your roof is going to be the best bang for the buck.

  33. Rating: +0

    Positive Negative

    Should we make the attempt to to cut the ridge and install ridge-vent? We are installing a new roof on a 10-15 year old contemporary post and beam home that has 6+ inches of spray foam directly to the osb sheathing with no air space alloted for a continuous vent system. I was at least going to try to cut away the foam to see if the drywall was part of the panel but do not want to damage the interior finish at that hard to get at area to make repairs. Should we save the homeowner some money and just cap it after a determination is made whether or not air space even exists? We ripped some very crispy shingles that are first generation architect that should have ten years of life left judging by the rear porch which is 3 season. I am thinking the ridge-vent will help the cap but not much more. Thanks for any input!

    I'd need more information to accurately provide some guidance. Based on what you've described - I say you need to go all or nothing on the sealed, foamed attic space. Either it is air tight and foam sealed, or it is vented - and vented well with holes in the bottom of the attic and holes in the top.

  34. Rating: +0

    Positive Negative

    I am building a garage/workshop with a loft. The side walls are 6" studs. I had 1" closed cell foam applied to the sidewalls and 6" open cell foam sprade on the roof trusses. I have a metal shingle (Decra) roof. I am going to add an additional R13 to the sidewalls. Should I consider adding a radiant barrier and if so, what would you recommend? The entire building will be heated/AC.

    Adding the radiant barrier inside your sealed space if going to have a very minimum benefit since there is already so much foam in place. To get the best results you'd need to add it from the outside, like right below the metal roof. If that is not an option, then you probably aren't going to see much of a benefit from installing it inside your attic space.
    For more info on combining a foam-sealed attic with radiant barrier, take a look at this article I wrote:

  35. Rating: +0

    Positive Negative

    I have passive gable vents at each end of my 1948 home and no soffit or ridge vents. I want to install a radiant barrier in the attic. Can I run the barrier to the soffit area and cover them up and can I cover the ridge area up as well since I have the gable vents or should I add soffit vents, if so how many? Would a fan at each end of the gable to pull air out be advised? I will add blow insulation after the barrier is installed.

    You still need to leave gaps for air flow regardless of the ventilation you do/do not have. Watch my video that explains this: Leaving Gaps in your Radiant Barrier Installation for Air Flow

  36. Rating: +0

    Positive Negative

    Hi there Ed, I'm in Madison Wisconsin. We have a 'hot roof', no venting, with 2" foam on the roof deck under the shingles, then the roof deck, then we've put about 3" of closed cell spray foam between the rafters and on the gable end walls. Some rafters are 2x4's (original to the 1914 house) and some are 2x6's (on the new attic dormer). So there's a little bit of air space left on the interior of 2x4 rafters and gable end wall studs (1/2" to 1"), and more air space on the interior of the 2x6 rafters (perhaps 2"-3"). With the cold winters, I'm wondering if there would be a benefit to either a foil layer over the remaining air space, or using foil-backed drywall? Or might this be more of a benefit for the couple of warm weeks we have in the summer? I looked at your page and it seems that our system is quite different from what you put together there. Alternatively, do you think it'd be worth it to pack the 2x6 rafter cavities with cellulose for the added R value? The full 5.5 inches of foam was going to be too expensive, so we didn't do that. Thanks for your advice

    If heat retention is your primary goal, then I do think adding radiant barrier to the bottom of the rafters would benefit you. Placing the foil there (or even on the attic floor) will give the foil the best chance to hold heat in the living space below the attic. Whether you staple to the rafters or lay it on the floor, the foil will be open to an airspace on at least one side so it will work.

  37. Rating: +0

    Positive Negative

    Hello, I have been doing research in preparation to finish our 3rd floor attic and I am getting so much conflicting information I'm stymied. Currently the room has ~12 " of blown cellulose on the floor. The pitched attic roof deck is uninsulated and the space is vented with soffit vents, gables and ridge vent. If we finish and condition the space, i am getting info that we should use baffles from the soffit to the ridge, apply the closed cell foam to seal, then either another open cell foam coat or batts to increase R value. I realize I would also need to do rigid foam at the soffit vents. I am getting other information that here in zone 4 (VA) you can forego the baffles and apply open cell foam directly on roof deck. Can you please help me determine the correct method of these, if either? I am completely confused.

    From experience I can tell you the best way to tackle this room is to use a combination of both a RADIANT BARRIER and foam (rigid foam board works best as far as attaching it to the rafter bays, spray foam will actually need something better than foil to adhere to, so many people use foam board on top of the foil and then spray foam the board until the cavity is filled). Basically you want it to look like this: roof deck, air gap (with or without baffles), radiant barrier foil, spray foam, interior of the room. This page has a detailed video on how to add the foil and insulation into the cavity so that the proper air gap for air flow is maintained, I highly recommend you take a look at it (and some of the photos on the bottom of the page) to familiarize yourself with the basics of how to set this up: Adding Radiant Barrier to a Cathedral Ceiling & Adding Radiant Barrier to a Wall
    The main ideas are: get the foil closest to the outside/roof with the proper air gap (and on any walls that share a space with the attic), allow air to flow between the foil and the roof deck (to help keep the assembly cooler, and utilize traditional (R-value) insulation closest to the inside of the room. If you can achieve these 3 goals, the room will be more comfortable year round.

  38. Rating: +0

    Positive Negative

    Can I spray open cell foam over LP Techshield?

    NO. Doing so will effectively eliminate the air space Techshield relies on in order for it to work. If you do this, you will render the radiant barrier useless. Not to mention spray foam doesn't adhere well to foil. If you're set on adding spray foam, you need to create an air space on top of the foil before the foam. Your best bet is to install like a cathedral ceiling with spacers and instead of adding a foil layer (since you already have one) you can add foam board. This will help add r-value AND the spray foam attaches better to the foam board than the foil.

  39. Rating: +0

    Positive Negative

    is there a advantage with radiant plywood vs open foam in a a new house

    Yes, combining radiant barrier decking and foam work well together - I have this system in my own home. Read more about it here: Combining Radiant Barrier with Spray Foam Insulation

  40. Rating: +0

    Positive Negative

    I am building a new single storey home almost 6000 sq.ft. We have installed radiant barrier plywoods and shingles on top. Should I go for spay foam insulation (Inceyne) or Fiberglass(Blown and Batts)?

    If your radiant barrier is radiant barrier decking, then it's using the attic space as an air space so you can't cover it with spray foam. In this case you could use spray foam (or batt insulation) on the attic FLOOR, but not directly on the foil in between the roof rafters.

  41. Rating: +0

    Positive Negative

    We are building a modern home with a single slope shed roof. We want to use black roofing metal but became concerned about the heat. The roof 36 feet by 60 feet and is constructed of engineered I joists with a particle board deck. What is the best way to insulate? My contractor originally said he would do spray foam insulation from below. Now he is talking about using double bubble foil insulation above the roofing felt and under the metal, along with insulation batts ( i think the owens corning ) in the joists. We are in North Geaorgia in what I saw was considered zone 4 climate. Thanks so much. -Jeff

    I recommend you install the foil as shown on this page:
    It allows for the air gap needed for the foil, plus regular insulation before the drywall/whatever material you are using for the interior ceiling finish. The foil MUST have an air gap in order to work to block heat, so you have to make sure that is incorporated into the assembly. Once you do that, add some R-value below the foil and you're good to go!

  42. Rating: +0

    Positive Negative

    Hi Ed: I'm in Houston in a 3 story house near the water. There seem to be very little blown in insulation in the attic. I was thinking of using your Attic foil for the roof rafters and 2" Dow Tuff R for the Attic floor and seal it with cracks with spray can foam. I would cut foam boards to direct the air flow from the soffet vents to the under side of the attic foil. The goal would be to encapsulate the attic floor yet still have attic ventilation. Your thoughts?

    Sealing the floor air tight is a great way to minimize the potential for condensation. Foil on the roofline will also keep the attic cooler, and consequentially the home too.

  43. Rating: +0

    Positive Negative

    Hi Ed, I am retrofitting a 80 year old barn are on an old feed store building, the roof is 44x80 shed roof at a 4-12 pitch with no penetrations. I am considering leaving the existing metal roof in place, laying down a 2" insulboard similar to Fomalar with sealed seams, 1x purlins and a new metal roof with an attached condensation barrier. I know the R value will be only around 7-8 but the area will be used only 5-10 hours a week. Increased insulation options are not in budget at this time,, Your thoughts?

    Your money and efforts will go a lot further if you add a radiant barrier to the layering. You can add it in place of the insulboard, the foil will reflect 97% of the heat coming off the new roof, so it never gets past the foil or into the barn. Bang for the buck it will go the furthest toward making the space below more comfortable overall. Check out similar installs on this page:

  44. Rating: +0

    Positive Negative

    Hi Ed, I just built a 30 by 18'room with 14 foot to 11' low point high vaulted ceiling. 2x12 rafters and radiant barrier foil back sheathing. I am going to use conventional fiberglass insulation and I wanted to know if even this insulation shouldn't touch the foil. I know you state it is not good to spray the closed cell foam on to the foil or it defeats the purpose. should I use an insulation that comes a little short of touching the foil on the plywood? Thanks so much. Nick

    Yes, it doesn't matter what type of insulation you use, nothing can touch the foil or else it will not work. Whatever you use, make sure that over time it will not sag and make contact with the foil, because once it does, the foil is no longer able to block radiant heat.

  45. Rating: +0

    Positive Negative

    Hi! Just started building my home and I am planning on total encapsulation. At this moment the materials supplier is planning on shipping me osb with foil face RB for the roof deck. I am also planing a standing seam metal roof. From the info I have gleaned from your site the proper method woud be to install the osb foil side up (toward sky) and use furring strips to provide an air gap under the metal roof. Is this correct? This is a north Texas home with a gable roof.

    Yes, that would be the best way to do it. Then, from inside the attic space you can spray the bottom of the deck directly to totally seal off the attic space without compromising the radiant barrier at all.

  46. Rating: +0

    Positive Negative

    I just purchased a multilevel,3800 square foot, 100 year old farmhouse in east Georgia. It has a metal roof and the HVAC is in the crawl space. It has 8" of spray foam insulation on the roof deck and 4" in the wall and crawl space. We live in the downstairs area(2400 square feet) that has 10" ceilings in the rooms. I understand that if spray foam is installed on the roof deck, I should take out the old blown in insulation in the floor of the attic. Since I am mostly concerned with heating the living space of the house, won't taking the blown in insulation out of the attic floors allow substantial heat transfer from the living space?

    If the foam makes a sealed, fully encapsulated, non-vented attic, then there should be very little difference with/without insulation on floor of attic. If it’s vented in any way, then you must keep the floor insulation.

  47. Rating: +0

    Positive Negative

    I have been researching radiant barriers for my attic space. I got an estimate to install a rigid foam board backed with foil on both sides to install to the rafters, making the attic a conditioned space. The estimate was over ten thousand dollars. I wanted to know if I could do something like this on my own. Is it ideal to attached radiant barrier foil to pink insulation foam on both sides, and then attach to my rafters, or should I just use the foil itself? Thanks!

    The foam isn't really necessary up on the rafters - it's really out of place up there. If you want to add it, then add it to the floor of the attic.
    As far as the foil install - yes, you can DIY! Check out this page as a starting point on how to install it (videos, photos, tips & tricks):

  48. Rating: +0

    Positive Negative

    Hi Ed. We are covering sheetrock on a cathedral ceiling with wood planks. Because the room is warm in summer and cold in winter, the plan is to first attach furring strips to create air space, then attach quilted radiant barrier, then the planks. For ease of attaching them, can we add a second set of furring strips over the radiant material? Would this a second air space cause problems? (The room is 12x16 and has a properly vented cathedral ceiling already.) Thanks so much; this is a very professional site!

    As long as the second air gap/space is a dead/sealed space that will be OK.

  49. Rating: +0

    Positive Negative

    My home was built in 1969. I have 3000 sq ft ranch in upstate ny. I have in my attic what appears to be a radiant barrier rolled out over the insulation between the ceiling joists. I want to add insulation to my attic as there is only about 5-6" of fiberglass up there now. Do I need to or should I remove that radiant barrier before I add more insulation?

    You can NOT sandwich the foil between layers of insulation; there must be an air space on at least one side of the foil in order for it to work. This means you need to pick the foil up, install your new insulation, and then lay the foil back down so it's the topmost layer, open to the attic air.

  50. Rating: +1

    Positive Negative

    I live outside Orlando Florida in a two story home. In the summer the upstairs gets very warm quickly and takes a while to cool with the A/C. I was thinking of spraying the underside of the roof with a closed cell foam(leaving room for the soffitt vents) or adding radiant foil.I was thinking the foam may help during a hurricane. What is your opinion?

    The BEST bang for the buck is going to be to get a radiant barrier in that roof! Foam isn't going to perform like radiant barrier because just like traditional insulation, foam slows conductive heat gain/loss, it doesn't stop it. Radiant barrier blocks 97% of radiant heat, meaning it stops it from entering the attic space and ultimately the home. Don't get me wrong - foam is a GREAT product, but if you had to choose one or the other - I'd go with radiant barrier because it actually blocks the heat.
    Since you mentioned you are trying to lower your electricity consumption (ie. lower your bill), I would also recommend you take a look at this page about how much you can expect to save:

  51. Rating: +1

    Positive Negative

    Is there a way to remove closed cell foam from the foil side of tech shield without damaging the foil? One of my installers mistaking my sprayed the rafter area instead of the joist/ceiling of a wine cellar. We need to remove the foam because the homeowner has been told that foaming the rafters is a bad idea because if you develop a leak over time your plywood will rot and someone can fall through. Any suggestions will be much appreciated.

    You can try scraping off the foam and see what you can salvage. Any patches that need to re-done could be patched with AtticFoil. If they have leak, water will dry out.

  52. Rating: +0

    Positive Negative

    I am installing foil backed OSB over foil faced PIC insulation board. How should the foil on each item be placed so the foils don't fight?

    The foils should face an air space - even if they share the air space. They won't "fight" per se, it's more of a minimal gain for the second layer. In a shared space scenario, it would be like what I did in my new home's double-deck system shown here:

  53. Rating: +0

    Positive Negative

    Hello, we are interested in buying a house its attic is foam insulated. The water heater and two ac furnaces are located in the attic, their exhaust line going though the roof but there is no fresh air ventilation system in the attic. All three units' main supply is gas for heating. In the roof, there is one duct probably installed for the ventilation purposes but it is cover with foam inside the attic. My questions are these. If we punch this duct from outside and provide some air for the attic, would it be correct? (I am worried about killing the foam insulation purpose). What is the best way to install a ventilation system for this attic?

    In a foam encapsulated attic you don't have ventilation; that's the whole point - it's sealed air tight. So no, I would no recommend punching out a hole to bring outside air in unless you want to potentially introduce moisture build up issues. What is your purpose for wanting to bring air in? Email me.

  54. Rating: +0

    Positive Negative

    Hi Ed, I'm about to insulate my garage door and have decided upon the reflectix product. My panels are 18inch high and upon searching for a product 18in X 100 i found Reflectix HVST1810002 indoor Double Reflective Duct Insulation Staple Tab. This product was designed for ducting, would it be OK to use? is there a difference in a duct insulator and any other?

    If it says "indoor" on the description, it might not be appropriate for a garage application. I'd contact them directly to ask about the difference and if it would work.

  55. Rating: +0

    Positive Negative

    I was given poor advice and I was redoing a roof. I had to re insulate from above. I was told to lay the propa vent down then the insulation then the decking this is a chathedrial ceiling house is this detrimental to the performance of the insulation putting the air gap between the foam board on the inside and the insulation rather than keeping the air gap next to the plywood?

    So it sounds like your are moving air between the sheetrock and the insulation? If so, this is terrible and needs to be remedied. I think your only option is to tear out the ceiling and reinstall properly as a cathedral ceiling should be. You can see the details on installation here:

  56. Rating: +0

    Positive Negative

    I have a very hot attic in south Louisiana. What is the bottom line on making the attic cooler, Spray foam or radiant barrier? Can I put the foil on one side of foam board and nail that board on the bottom of the rafters on the roof, leaving the 6" space between the foam board/foil and the decking of the roof? Would this give me any benefit of extra insulation? Thanks

    Foam isn’t going to perform like radiant barrier because (like traditional insulation) foam slows conductive heat gain/loss, but it doesn’t actually stop it. Radiant barrier foil is different than spray foam because AtticFoil’s reflectivity of radiant heat is 97%, meaning you stop the heat from ever even entering the home. Staple the foil across the bottom of the rafters and that is it! There is also no real benefit to adding foam board up on the rafters - the radiant barrier on its own will work great and you could add the foam board to your attic floor, against the living space below if you wanted to include it.

  57. Rating: +0

    Positive Negative

    I am installing a new tile roof on my house can I put the radiant barrier on top of my felt paper and will this help keep the heat out.

    If the tiles have a naturally occurring air gap or are on a batten system then yes - you can add the perforated foil on top of your felt paper to block 97% of radiant heat from coming in through the roof. Install instructions and install video are here:

  58. Rating: +0

    Positive Negative

    I have 1&1/2 story home, in Houston, with 12-12 pitch roof. 5 months ago, I installed TechShield (foil backed) decking under new roof and while roof was removed, installed 1 to 2 ft of GreenFiber R Blown-In Insulation for Attics floors. Now I'm doing interior remodeling, removing sheet rock ceilings & perimeter walls, exposing 1/3 of my homes studs & rafters. I would like to remove bat insulation in between studs and spray foam insulation. Also, want to spray between rafters but, want to know the best way to keep the radiant barrier benefit of the foil backed TechShield. Your input is much appreciated. Thanks in advance.

    The only way to preserve the Techshield's ability to block radiant heat gain is to keep the required air gap for the foil facing to work. I do know what LP recommends for the minimum air gap for their product, so you will have to contact them to find out for sure. It's possibly going to get tricky and expensive to do this - you basically will have to find a way to create the air on top of the foil surface (probably using spacers) and then add an intermediary layer that the foam can attach to.

  59. Rating: +0

    Positive Negative

    Hi there, I live in Phoenix, AZ. I am adding on to my home with a flat trussed roof. I plan to use foam for my roofing. I also plan to use radiant barrier sheathing. Will it help for me to batt insulate the underside of the radiant barrier sheathing to increase the R value?

  60. Rating: +0

    Positive Negative

    Our attic stair zipper closure has lots of condensation when we pull down the attic stairs - we are in a newer home but we are already seeing signs of rust on the stair hinges. What is the culprit? Could the builder have installed this incorrectly?

    Certainly a builder could have installed the stairs incorrectly, but that may not be the issue. Moisture is a result of warm-moist air coming in contact with a colder surface. So likely your stairs are LEAKY (not uncommon at all) or the stair cover wasn't sealed properly when it was installed. Find the source of leaking air and you'll solve the moisture issue.

  61. Rating: +0

    Positive Negative

    I have a client who is requesting a specific detail. He wants to apply a layer of 1-1/2" 4x8 rigid foam panel followed by a 2-1/4" rigid foam panel staggered. On top of that a layer of tech shield or solrboard plywood with foil side up, underlayment then shingles. Although the foam is giving insulation the radiant plywood would not unless placed over 3/4" furring strips and foil side down correct? This is all installed over a cathedral roof with no interior access to rafters and no attic.

    Correct. The foil side of the plywood product must be facing an air space or else it won't work. Every single spot it is being touched, it's gonna just transfer the heat right on through. The only way to do this right would be to use the furring strips like you mentioned OR to flip it over and have some space between the rigid insulation and the foil side.

  62. Rating: +0

    Positive Negative

    Can the radiant barrier foam board be installed between rafters and against roof decking?

    If you place the foil side right against the decking, the foil will NOT be able to perform as a radiant barrier. In that set up, you would only benefit from whatever r-value the foam has since the foil will conduct heat right through itself into the foam. A better use would be adding it to the bottom of the rafters.

  63. Rating: +0

    Positive Negative

    hello, i live in illinois and when the temperature drops below zero frost forms on my roof rafters.When the temperature rises the frost melts and drips onto the ceiling.We are now seeing water seepinbg through the drywall inside the house. Most of the water is along the edge of the walls that have a outside wall. there is one spot in the middle of a room. We have 16inches of insulation we put in the attic several years ago and just had a new roof put in this year. They put extra mushroom vents on the roof along with one solar powered power vent. The gutters and soffits and facia were replaced. We have noticed the water for several years but never to this extent. Any ideas why the frost is forming and what to do to stop it?

    Frost is a problem associated with warm air from inside the house "leaking" into the attic. When the moisture condenses on the rafters, frost can form. Then, when the outside temperature rises again, the frost thaws, water collects and can leak into your house. Adding more attic ventilation is probably not completely the right solution. Additional roof vents do allow more air to move and keep things dry, but in a case like this, they also can pull more warm moist air from the house and into the cold attic.
    The better solution is to check for the obvious leaks in the ceiling and seal them. Then, you should make certain that you have the adequate level of insulation for your climate area (over time insulation settles and you lose R-value). Then, you should cover your insulation with an air barrier as a final step. Watch my video here on why this is a huge energy saver and helps keep the house warmer in the winters:
    All of that combined should eliminate your frost problem.

  64. Rating: +0

    Positive Negative

    Hello. I have a low pitch cathedral roof (3/12) that is 36 feet in length from vented soffit to ridge vent . The roof joists are 2X10 construction, 24" OC with foil backed drywall on ceiling. Currently there is fiberglass batting with a 1-2" air gap below the roof sheathing. Due to length and low pitch, I feel adequate ventilation has always been questionable. I am in the planning stages of getting roof replaced. However, I want to convert to closed cell spray foam first. Essentially, all of the exterior sheathing and fiberglass batting would be removed topside, exposing the foil backed drywall. I was planning to have this spray foamed but have concerns on the adhesion to the foil. Will this be a problem? Does it make sense to cut and install thin foam board into cavities before foaming? Can an experienced sprayer maintain a reasonably consistent foam thickness (7') to ensure I have a decent air gap above foam for ventilation? Is anything required above finished spray foam before sheathing is re-applied? Appreciate your thoughts and recommendations. Kent - Prior Lake MN

    No concerns with the foam sticking to the foil - the foam sticks to anything. It would make sense to cut and install thin foam board before foaming, but it's gonna be a lot of work!

    Can an experienced sprayer maintain a reasonably consistent foam thickness to ensure a decent air gap above foam for ventilation? Yes, but 7” of closed cell foam is a LOT of foam!! They would have to do 2-4 layers to keep from having spontaneous combustion.

    For the finish, I’d recommend installing foil over the rafters and pushed down an inch or two like I show on this page:

  65. Rating: +0

    Positive Negative

    Good morning. I am building a house in the Caribbean. For aesthetic purposes I chose a dark colored metal roof. I know, not the best for heat gain. I plan on installing drywall to the underside of the rafters. I want to implement the best possible solution to keeping the space cool. Keeping the A/C cool at night and preventing heat gain during the day. Was thinking of a combination of batt insulation with a radiant barrier, or looking into rigid panels that have a foil backing... Any suggestions. Any silver bullets out there? Any help would be greatly appreciated. thanks!

    Hands down, this is the best way to do an installation like this: Hands down, this is the best way to do an installation like this: Adding foil to a cathedral ceiling.
    Outside of that, even just the radiant barrier alone will provide a significant difference in the heat gain.

  66. Rating: +0

    Positive Negative

    Hi. Love your site and videos! And apologize if you've already answered these questions. 1) I have an older home with 4 vertical soffits and 2 gable vents (for intake). If I'm not blocking any soffits, can I maximize foil coverage all the way to the bottom or should I leave a few inches regardless? I understand I'm suppose to leave room across the top regardless for the exhaust vents. 2) It's been a hot summer on the west coast! I'm thinking to add another stiff foam insulation with foil already on one side to the attic ceiling (not the floor). This will go between the rafters and then I'll cover the rafters with attic foil. I understand the air space requirement between the two. Is this worth the cost, savings, and extra work? And is this more like a 5% improvement? Thanks for any help I can get!

    Hi, thanks for the questions!
    1. You still need to leave a gap, regardless of the ventilation you have (or don't have).
    2. No, this isn't beneficial. If you have r-value (like the foam board), it belongs on the attic floor, not the rafters.

  67. Rating: +0

    Positive Negative

    do they make a 1'x4x10' radiant barrier rigid foam for underneath roof decking

    Not that I know of. If you're adding radiant barrier under decking, you'd want to drape it anyway, like this:
    Also, there's no benefit to adding r-value to the roof line unless it's a cathedral ceiling construction, in which case you still would not add the foam outside the envelope like that. It belongs closer to the living space like I show here:

  68. Rating: +0

    Positive Negative

    I live in CA with long spans of time over 100F and have a low sloped roof. I bought SmartShield 5 mm with foam inside and originally intended to staple it on roof rafters and use Rockwool on the floor of the attic. But the roof is so low that it won't allow floor insulation on the edges. Is it a good idea to use the SmartShield on the roof under tar paper and then the shingles? And use R15 insulation between roof rafters and R30 on the attic floor?

    No, it's not a good idea because radiant barriers ONLY WORK if there is an AIR GAP on one side of the foil. Sandwiching foil between shingles and tar paper doesn't have an air space. It's a waste of time and money. You're better off adding your R-15 on the floor and then covering that with a layer of SuperPerf AtticFoil on top of the insulation like a blanket:

  69. Rating: +0

    Positive Negative

    What is best foam to use around old lighting fixtures in my attic so I don’t lose so much heat. And what can I put between my chimney and walls so I stop losing heat through the 3” space gap

    A can of spray foam (Great Stuff) is perfect for this!

  70. Rating: +0

    Positive Negative

    I have cathedral ceilings throughout my house. i don't want to ventilate, I want to spray 4" closed cell insulation against the bottom of the roof deck, then R19 batt below. My framer installed Tech Shield radiant barrier sheathing. Aside from losing the benefit of the radiant barrier, can I spray the closed cell directly to the tech shield without any other adverse effects? From my research it would be most $ to baffle and ventilate than the premium I paid for the tech shield. Advice?

    Well, the foam may not stick well to the foil on the Techshield - at least that has been the feedback we have received. Also, beyond losing the radiant barrier benefit, you're also ADDING a conductor to the roof, and aluminum is a very good conductive material. So where as before it blocked heat gain/loss, now it will promote/add heat gain/loss as a conductor. Something to consider - cost isn't always about dollars and cents...

  71. Rating: +0

    Positive Negative

    I live in the north east and I built a wood framed pole barn with steel on exterior. I put house wrap over the wall purlins before installing the steel walls. Inside I installed 1.5 inch foam board with foil on both sides between the purlins and taped all seems. I want to install another layer of the same 1.5 inch foam board over the first and stagger the seams to attain approximately an r-20 value and tape those seams also. I was thinking of putting 3/4 inch air gap between the two layers to maximize the reflective properties of the foil facing. Or should I be concerned about trapping moisture in this air space and place the two layers against each other?

    If everything is as airtight as you said, then you should be able to leave the ¾" gap between the 2 to get the maximum results out of your foam board and your radiant barrier. Send us some photos - would love to see it! Also, have you seen our BlueTex metal building insulation products for metal buildings? Learn more here:

  72. Rating: +0

    Positive Negative

    I have radiant roof decking(tech shied): howver, ny attic is still hot. I thought about spray foam on the decking but read that would prevent the radiant from working....

    Yep - it will negate the entire benefit of the radiant barrier decking. Is it the AIR that is hot? If so, you probably need more/better ventilation through the space. If you're concerned the surface temps are still too hot, then you can also consider putting another layer of foil below the foil-OSB; this method will definitely yield better results than the radiant barrier decking alone since it will block thermal bypass coming off the rafter ends too.

  73. Rating: +0

    Positive Negative

    We're installing polyiso rigid insulation between rafters in the cathedral ceiling of our new sun room. (Maine) The 3 layers gives us 6" but the rafters are 7 1/2." Is it ok to leave a gap between these 3 layers and the final lower layer (which will run horizontal to prevent thermal bridging at the rafters)?

    It's ok, but why not fill it with a layer of foil insulation to help hold heat in there in winter? Or spray foam in there to really seal it up? You can leave it bare, but I'd take advantage of that space and maximize it.

  74. Rating: +0

    Positive Negative

    Building a new home on the Texas gulf coast with a flat roof. Builder did not put techshield under shingle roof. What would be better spay closed cell insulation or radiant barrier and regular insulation?

    Without knowing additional details, it's hard to say but purely on science and how each functions, you'll probably be better off with radiant barrier + normal insulation vs. just spray foam. Why? Because unlike foil, foam doesn't stop/block heat, it simply slows conductive heat gain/loss. Foil reflects 97% of the heat away which yields a better overall results and then the layer of regular insulation below the foil layer will slow down any heat that makes it past the foil. A GREAT option would be installing radiant barrier foil AND spray foam!

  75. Rating: +0

    Positive Negative

    What is better to use in a residential flat roof replacement GAF ISO Barrier Board or radiant barrier plywood? We have about 20inches of 30R insulation between our ceiling and roof and want to add insulation when getting a new roof.

    If the new roof won't have an air gap for the foil side to face, then there's no point to using that material and I'd go with the ISO board. Otherwise if you CAN get the foil side facing at least a ½" of air space (dead or vented air - it doesn't matter), then I'd use the radiant barrier board every time!

  76. Rating: +0

    Positive Negative

    I have a metal garage that only has the bubble wrap style radiant barrier. My metal posts are about 5 feet apart. So open cell foam or closed cell foam seems to be the way. My question is with open cell do you leave the radiant/vapor barrier up and spray over it. I hear some people say leave it up and some say take it down. With closed cell I hear take it down. Any thoughts on this. Thanks

    Unless you are trying to seal up the garage and make it semi conditioned then foam won’t help much more than foil. If you are trying to keep it warmer then you would seal it up and add r value to the door.
    You would do basically the wall method. Door - air space - foil - foam.

  77. Rating: +0

    Positive Negative

    Last fall, a contractor sprayed open-cell foam on our roof decking, attic walls, and the attic floor. Our roof contractor said the attic is staying hot because nails on shingles are popping up. The roof was new Feb 2022. I think we need to vent hot air out or allow cool air into the roof. Any recommendations?

    If you spray foamed the decking, the walls and the floor, then the attic does not need to vent - it's a sealed space. When you properly encapsulate an attic, you stop all exchange of air with the outdoors, as infiltration is a source of moisture.

  78. Rating: +0

    Positive Negative

    Hello, I have a walk in attic where the attic wall is on one side and the other a closet. In the summer you can really feel the heat. It is insulated on the attic side with the craft paper against the sheet rock. Can I screw rigid foam sheets over the existing insulation? Or do I have to remove the insulation and cut the rigid in between the studs? Thank you so much in advance.

    Yes, you can add the rigid foam over the insulation, screwed onto the studs. I'd recommend a foam board with radiant barrier, installed with the foil side facing the attic space, for maximum benefit.

  79. Rating: +0

    Positive Negative

    New construction second floor in climate zone 5. 4/12 trusses 24”oc on 2x6 walls 16”oc. I’m thinking of adding 1” foil faced polyiso in ceiling before blown insulation. Not sure if I want to use furring strips or add blocking between trusses then lay polyiso in place and foam seal edges to bottom cord of truss. Time consuming either way. Is it worth the extra work and time? Will I see energy savings?

    If you're converting that second story into a climate controlled space, there's only one way to do it right where it justifies the cost and time and it's shown here:

    This method is 100% worth the effort - no other product or process of construction is going to help keep it cool in there like this will.

  80. Rating: +0

    Positive Negative

    We have a 2,850 sq ft home that was built in 2019. DFW area. Attic has radiant barrier on the ceiling and blown insulation on the attic floor. We are thinking of switching to spray foam insulation just to hopefully reduce the electric bill and save wear and tear on the ac unit. We understand that the blown insulation on the floor will have to be removed. Walls put up to seal off the area from the garage,etc. One contractor tells me he will spray over the radiant barrier on the attic ceiling. Another says all insulation has to be removed & you can’t spray foam over radiant barrier. Who is correct and will the $13,000 expense be worth it?

    The contractor who said you can't spray on the radiant barrier is correct - if you cover the foil surface it will no longer work. Your best best is to spray foam the attic FLOOR (seal it up airtight) for maximum energy efficiency and keep the attic vented with the radiant barrier on the roofline. This allows the roof to minimize the heat coming in the attic, flush out warm air, and then the foam reduces heat flow downward AND keeps the conditioned air down in the living space because it's sealed up.

  81. Rating: +0

    Positive Negative


    Love spray foam enclosed attics.  However you typically can’t install a radiant barrier with this type system. Take a look here to what I did with my home which has a full foam attic AND a double radiant barrier.

  82. Rating: +0

    Positive Negative

    I live in a hot coastal climate with no a/c or heating in the house. In the long summers it is often uncomfortably warm in the house. The house has vaulted ceilings formed with beams and the plywood that is really the bottom of the roof rather than a proper ceiling. There is an immense transfer of heat through roof into the house, so I've been trying to find the best approach to insulate spaces between the beams. Thinking some combination of foam board and radient barrier finished with wood slats to cover, but unsure exactly how to approach it. Thanks for the help!

    Yes, rooflines like this can get unbearably hot in the summer, especially as everyone's summers seem to be getting hotter and hotter each year. The best way to approach insulating a ceiling like this is shown here:

    This method will allow you to combine radiant barrier and traditional insulation for the best results and increased comfort year-round.

  83. Rating: +0

    Positive Negative

    Our 1925 house has 3 rooms with no attic - so no way to insulate those rooms. The house is stucco. Can we put 1/4 " pink foam board on our inside ceiling then put tongue and groove boards over it to make room warmer?

    At only 1/4" thick, its R-value is practically nothing and you will probably never recoup the cost of the material or the installation. Basically, it is just a waste of money if the foam board that is installed is not at least 3/4" thick or more.

  84. Rating: +0

    Positive Negative

    2” EPS with one-sided foil vs Foil Radiant Barrier on underside of rafters in an attic? I have a large attic with R-30 in the ceiling joist cavity, but attic temps still soar in the summer. HVAC and ducts are in this unconditioned space. I want to reduce the temps the most efficient way and lowest cost possible a s a DIY job. Curious about best method. Thank you!

    The best thing to do in this attic space is to add a FOIL ONLY product to the bottom of the rafters. The EPS provides virtually ZERO benefit in a vented attic being on the rafters. The better place to add it, if you want to use it, would be on the attic floor, right above the thermal envelope (living space) below.

  85. Rating: +0

    Positive Negative

    Can I put 3 inches of closed cell Sprayfoam in my attic and then put R -38 fiberglass over that and then R-19 blown in cellulose over that

    Sure, you can do that... not sure it's beneficial or necessary, but it can be done.

  86. Rating: +0

    Positive Negative

    Does faced insulation board help keep Sun heat out ?

    It can reduce the conductive heat gain but a radiant barrier foil like AtticFoil is the better option to reflect the sun's radiant heat.

  87. Rating: +0

    Positive Negative

    Hi Ed! I live in West Texas, west of the 100th meridian, with a very hot dry climate zone 3B. My attic is blazing hot and my ac duct work is all in the attic. This places an extreme load on my A/C. The majority of the heat gain in my attic is from radiant heat gain. I was wanting to place attic foil under my roof rafters. I was wondering if I would receive additional benefit from also using insulation between the rafters (using compression fitting or supporting it with insulation hangers), under the roof deck, and over the foil? Would there be any significant benefit from doing this? If I use insulation in this matter, should I keep it from touching the foil? David

    Hi David, thanks for the questions. So no, adding r-value to the rafter cavities on the roof will provide ZERO benefit to cooling down the attic space and will in fact keep your roof hotter longer. The best approach is to use AtticFoil on the roofline and then make sure you have plenty of ventilation moving through the attic (both the area between the foil and the roofline AND the inside of the attic space). With AtticFoil stapled up and good ventilation, your attic temps can get to the same as ambient temp no problem.

  88. Rating: +0

    Positive Negative

    Hello, Q about insulation under a metal roof. It was put over and screwed to furring over the there is a 3/4" space to the roof. Can I just put a foil insulation board on the underside of the roof and then add insulation to the underside of that to create not only a reflective barrier but also the insulating factor with the batts then sheetrock? It should also do to the ridges in the metal roof create a baffle like air flow from the soffit to the roof vent it is a catheral as well??

    No, you can't sandwich the foil in the rafter bays with insulation. You will have to create an AIR GAP in the rafter cavity if you want to use the foil in there. This is the best way to do it:

  89. Rating: +0

    Positive Negative

    Hi there, I was recently told by a chemical/air engineer that it was a very bad idea to blow in loose fill fiberglass insulation in an attic that has had its roof line foamed. He told me it depletes oxygen in the house and creates a moisture barrier that will allow mold to grow. This doesn't make much sense to me for multiple reasons, so I called a corporate insulation manufacturing company and talked to the research and development department. They told me that this was completely untrue, and couldn't understand went the engineer would have told me that. Is there any documented proof backing this engineer's claim? And either way, could you give me better understanding of why, or why not? Any help is appreciated. Thank you!

    If the attic is fully foamed (sealed) non-vented, then there is really no need for a layer of fiberglass at the roof line since the roof is now your thermal boundary. It’s kinda like insulting an interior wall. As for the oxygen? He may have meant air; the home will definitely be higher with a foam closed attic - which is good. However, if an air conditioner is oversized it can result in short-cycling (basically not running long enough) to remove enough moisture which can lead to mold and other moisture related problems. The solution is to properly size (usually downsize) the AC unit, use a variable speed / inverter/part load type AC system, or possibly you need a dehumidifier. Foam is great when the AC system is properly designed for the lower heat load.

  90. Rating: +0

    Positive Negative

    I have a cinder block house with non insulation. I live in Texas and the house faces the west. Sunset can raise my indoor temperature by 5 degrees. I plan on putting Hardie backer siding on the house this summer. I can't decide if I should do a house wrap radiant barrier (fured out for an air gap and sealed joints) or rigid foam with a radiant barrier built in?

    Either way you go you have to create the air gap. The foam will give you a little R-value which is important if you're cooling the house with cold air/HVAC. Again, you have to create the air space on the foil side of both the foil/foam product and just regular AtticFoil House Wrap. If we are just talking about a 5 degree difference though, you may not need the r-value from the foam.

  91. Rating: +0

    Positive Negative

    Live in NC hot in summer cold in winter, attic has blown in fiberglass with no vapor barrier, am considering adding radiant barrier foil to underside of roof rafters- should this be perforated or solid


  92. Rating: +0

    Positive Negative

    Have 2nd house in Louisiana with metal roof adhered directly to rafters vented at eaves, ridge and power fan in one gable. Attic floor has insulated ductwork and blown in insulation. 1) Can one inch of Closed Cell Spray Foam be applied over blown insulation and ductwork to a) reduce cooling load and b) provide a waterproof covering to protect interior if roof panel blows off (not sure if poly Vapor barrier was applied to ceiling before gypsum board was installed; don't think so but will check when I go down on Vacation in a week or so. OR do I have 2-3 inches of Closed cell sprayed on metal roof and rafters sealing eaves, ridge and gable ends to create an unvented space and leave the blown in place. Appreciate your input. Thanks

    If you want to add the foam, then you're better off adding it to the underside of the roof and sealing off the attic space to make it a non-vented/ air tight extension of sorts of the thermal envelope.
    Adding foam over blown-in/fiberglass will not work.

  93. Rating: +0

    Positive Negative

    Hi Ed, I recently had a home built in Florida. When adding ceiling speakers, I noticed that a radiant barrier was installed, but no attic insulation was added. Specs call for R38. Radiant barrier sounds awesome, but I'm assuming I need insulation also? Thanks!

    Yes, you are correct that you need BOTH in a home. The insulation should be right up against the rooms in the home and the radiant barrier should be the last layer (either on top of the insulation OR on the roof rafters/underside of the roof deck. More info here:

  94. Rating: +0

    Positive Negative

    Two years ago we removed the fiberglass from the attic floor and had Demilec Agribalance open-cell spray foam installed. Baffles were installed to protect the soffit venting and there is something like 83 feet of ridge venting. They " re-installed " the 7/16 osb flooring which covers most of the attic floor. Last year we had a Futureroof slate-look steel roof installed. All seems good, but I would like to get the attic temperature a little cooler in the summer. My furnace/ac buddy tells me that temps of 110-115 are nothing to be concerned about. I have purchased, but not installed yet, some small fans that we will position at the ridge to enhance the ventilation. I know that this is probably overkill. What advice, if any, would you suggest. Climate zone 5 near Pittsburgh, Pa. Thanks,RgN

    If you want the ATTIC temp lower, then staple up the foil to the bottom of the rafters. That being said, keep in mind that because it's not a cooled space, the BEST results you can get on a non-conditioned space is equal to outside air temps. For more info on how this works and realistic expectations of a space like that, see the video on this page:

  95. Rating: +0

    Positive Negative

    I have a home built it 76 that's about 2000 square foot plus an attatched garage that's another 750 square feet. I have a 2 stage bryant evolution heat pump plus a propane furnace on a 500 gallon in ground tank. This winter in Maryland has been very cold. I just got an estimate of 6,000.00 to att 6" of spray foam to the bottom of my 2x8 upper roof trusses and gable ends. I currrently have about 12 inches of fiberglass blow in on the bottom of the roof trusses. I had assumed it would be best to spray foam the entire attic but the contractor said to leave the blow in there. I'm worried that all of the protrusions through the ceiling which number about which number about 29 between light cans, smoke alarms, and ceiling fans will still alow a lot of convection of heat into the attic. Also I have several rolls of radiant barrier that my framer would not install should these still be incorporated into my attic? I'm also concerned that the pay back period will be very long spending 6G on the spray foam I'm spending about 2000 a year on propage which included my 40 gallon hot water heater with a family of 4.

    Adding radiant barrier will not only make the insulation you already have more effective, but it will go the furthest in terms of investments and ROI. The foil immediately blocks 97% of heat transfer - whether that is heat getting in during the summer or heat getting out in the winter.

  96. Rating: +0

    Positive Negative

    I have a storey 1/2 house, if I want to redo the insulation,can i remove the drywall and use spray foam and spray it onto the roof shetting.Thanks norm

    Yes, you can do that.

  97. Rating: +0

    Positive Negative

    Hello. I have an attic / crawl and a cathedral ceiling living room. Can I do spray foam on the cathedral and leave batts on my attic /crawl? Thanks


One thought on “Attic & Foam Insulation

  1. It’s difficult to find experienced people about this subject, but you sound like you know what you’re talking about!

Leave a Reply

Your email address will not be published. Required fields are marked *