Its raining in my attic!!

Not enough insulation depth to stop condensation from forming on the surface of this spray foam roof line. The BER does not recommend installing a flash and batt attic roof installation unless you install enough spray foam to ensure that the surface temperature of the insulation does not drop below the dewpoint temperature of the warm, humid inside air. Also, the surface texture of the insulation will not allow the batt insulation to maintain complete contact with the spray foam, rendering the batt insulation an R-value of close to zero. Not to mention that gravity will eventually pull the insulation down and away from the roof deck in any case. It only takes a small air space to completely devalue the batt insulation. We recommend either spraying the full IECC code required R-value depth in the roof deck, or a flash and net/spray in place fiber or cellulose insulation that is fully supported with rigid backing so it does not sag and separate from the spray foam surface. In any case, the spray foam should be at a sufficient depth to ensure no condensation will form on its own, regardless of what additional insulation you install beneath it.

Comment

You need to be a member of Home Energy Pros to add comments!

Join Home Energy Pros

Home Energy Pros

Home Energy Pros was founded by the developers of Home Energy Saver Pro (sponsored by the U.S. Department of Energy,) and brought to you in partnership with Home Energy magazine.

Latest Activity

tedkidd commented on Scott Mellberg's blog post Lessons from Energy Efficiency Advisors: Getting Homeowners Onboard with Home Performance
"David,  Please think some of these things through.  If programs suck so much, how can…"
6 minutes ago
Hannah Finch posted a blog post

Stump Duncan, Innovate with Colby, and Save on RaterFest! 2014

RaterFest! 2014 Speaker Spotlight!Presenter:  Duncan PrahlTopic: Duck, Ducks, and more Ducts…See More
41 minutes ago
David Eakin commented on Scott Mellberg's blog post Lessons from Energy Efficiency Advisors: Getting Homeowners Onboard with Home Performance
"Consultation and education are all well and good, but we have found that the…"
1 hour ago
Kari Sauder commented on Scott Mellberg's blog post Lessons from Energy Efficiency Advisors: Getting Homeowners Onboard with Home Performance
"I just had a customer bail out of the whole house approach over the weekend.  It is a small…"
1 hour ago
Profile IconLOUIS ANDERSON and Jeremy Hargreaves joined Home Energy Pros
3 hours ago
Ramon Aguirre replied to Tom Conlon's discussion Whole House Fans - Love 'Em or Not?
"Whole house fan basically serves the purpose of exhaust fans. They are more cheaper than air…"
11 hours ago
Brandon Walton commented on Brandon Walton's photo
Thumbnail

2014-07-25 15.17.30

"While performing a QC it is always good to look inside the return.........."
19 hours ago
Brandon Walton posted a photo

2014-07-25 15.17.30

Supposed Sealed Return Chase
19 hours ago
Brandon Walton commented on Diane Chojnowski's group Facebook Pages
19 hours ago
Brandon Walton joined Diane Chojnowski's group
Thumbnail

Facebook Pages

Does your company or organization have a Facebook Page?This group is for pros who have facebook…See More
20 hours ago
Brandon Walton posted a discussion

12 Things Every Home Performance Contractor Should Have on Their Work Truck

Every home is unique and differs from the last. It would be a perfect world (from a project…See More
21 hours ago
Brandon Walton posted a blog post

12 Things Every Home Performance Contractor Should Have on Their Work Truck

Every home is unique and differs from the last. It would be a perfect world (from a project…See More
21 hours ago

© 2014   Created by Lawrence Berkeley National Laboratory.

Badges  |  Report an Issue  |  Terms of Service