Detail for Foam-Insulated Attic
suect
| Posted in General Questions on
I have a foam insulated attic. The board that meets the outer wall and ceiling is entirely exposed. Should foam be covering any portion of this?
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Replies
SueCT,
Are you describing the gable end of the roof? Can you take a picture and post it? Also tell us your climate zone or ZIP code?
My apologies,
I just read this.
I’m located in San Antonio, Texas climate zone 9, I believe. This would be located along the lower soffit of a gable end. Inside the home there is a 30 degree angle that is 2 feet wide between t to he wall and ceiling, as if that section is parallel to the lower roof.
SueCT,
Bexar county is climate zone 2A. (See https://www.energy.gov/sites/prod/files/2015/10/f27/ba_climate_region_guide_7.3.pdf for details.) Construction climate zones and plant-growing climate zones are different things (but it is easy to confuse the two when someone asks).
I'm still having trouble visualizing your roofline. In any case, you want to establish a consistent boundary between the exterior and interior. If you are conditioning the attic at the sheathing, you want spray foam applied to all the sheathing sections that interface with the outdoors. This article includes critical information on this topic: https://www.greenbuildingadvisor.com/article/creating-a-conditioned-attic.
As the article says, there are risks associated with installing open cell foam. You can manage these risks by eliminating air leakage into the attic and controlling humidity levels in the living space.
Again, pictures would be helpful. Maybe Dana Dorsett or another GBA expert will weigh in with better advice on your situation.
Thank you for clarifying the zones!
Here are photos of inside finished area and outside roof line.
I have noticed my drywall rippling slightly in this area.
Keeping the humidity below 55%. What would the recommendations be for a home with foam?
I’m thinking there may not be an answer on how to best approach this?
Sue,
I will give your post a bump.