How can we fix a sloppy open cell sprayfoam installation in an unvented roof assembly?
The house in question is located in Climate Zone 4 and is a gut-rehab striving for ENERGY STAR certification. The attic space does not provide enough height for a vented fiberglass batt assembly, so we decided to use sprayfoam to create an unvented roof.
We recently hired an insulation contractor to apply “Random Fill 5 1/2″ Open Cell Foam R-20″ sprayfoam to the underside of a roof deck. The foam varies in thickness from 5″ – 7” but includes some voids and holes. There are a few locations where the foam didn’t expand to fill the entire cavity, as well as some locations along the perimeter that were missed or shadowed during installation.
Can we use closed cell canned sprayfoam to fill in the holes? Is there another feasible solution? We are concerned about air and vapor barriers, especially with respect to envelope air infiltration and long-term durability.
They added R-19 batts underneath to meet the minimum R-38 attic insulation requirement.
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S. Thiel Butner,
I hope you haven't paid the contractor yet. Insist that the contractor come back and fill the gaps and holes. If the contractor refuses, contact the spray foam manufacturer.