Comments on: Attic Ventilation – Don’t Mess It Up

By: Ed Fritz

Ed Fritz — Tue, 24 Jan 2012 14:14:26 +0000

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.

By: Kyle

Kyle — Tue, 24 Jan 2012 13:46:32 +0000

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.

By: Keith

Keith — Mon, 07 Nov 2011 17:53:20 +0000

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!!!!!

By: Ed

Ed — Mon, 24 Oct 2011 18:18:26 +0000

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.

By: Cher

Cher — Sat, 15 Oct 2011 21:16:01 +0000

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.

By: Ed

Ed — Fri, 07 Oct 2011 18:43:02 +0000

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.

By: Erin

Erin — Tue, 20 Sep 2011 01:47:40 +0000

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??

By: Ed Fritz

Ed Fritz — Mon, 19 Sep 2011 02:48:58 +0000

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.

By: Ed Fritz

Ed Fritz — Mon, 19 Sep 2011 02:42:38 +0000

Craig, 1) I would go with foil over paint. Not just because I sell foil 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.

By: Don

Don — Wed, 14 Sep 2011 18:13:08 +0000

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