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.

Views: 338

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

Al Tibbs posted photos
2 minutes ago
Al Tibbs shared Lester Shen's blog post on Facebook
22 minutes ago
Hannah Finch posted a blog post
8 hours ago
Hannah Finch updated an event
Thumbnail

RaterFest! 2015 - Mark LaLiberte Keynote at Estes Park

September 18, 2015 at 3pm to September 20, 2015 at 3pm
RaterFest! is EnergyLogic’s  incredible two and a half day training conference nestled amongst the…See More
8 hours ago
Kerry posted videos
9 hours ago
John Meniatis posted videos
9 hours ago
Steve Schmidt joined Sean Lintow Sr's group
Thumbnail

Best Practices (Residential)

Best Building, Retrofitting, or even Auditing Practices - what are they, what should change, what…See More
9 hours ago
Profile IconDonna Lynn Saufley, John J Gilchrist, Steve Schmidt and 2 more joined Home Energy Pros
9 hours ago

© 2015   Created by Lawrence Berkeley National Laboratory.

Badges  |  Report an Issue  |  Terms of Service