Spray Foam On Attic Drywall: Not everyone knows that we can apply spray foam in an attic. The picture below was taken in the attic of a home in Town & Country MO. We applied spray foam on top of the drywall. If you look closely to the left of the picture you will see what looks like a big mound of spray foam. We used extra foam to air seal around can lights or other places where there could be an air leak. The idea is to make sure air does not leak out of the house through cracks or gaps causes by wiring; plumbing; interior wall connections; lighting ; etc. Air leaks are wasted energy which drive up utility bills. We sometimes blow loose fill cellulose or fiberglass insulation on top of the spray foam to increase the R-Value of the attic insulation system in an economical way. For example, we might apply R13 spray foam to air seal and insulation and then blow in R36 cellulose to bring the total R-Value to R49 (R13 + R36). Spray foam is more expensive than cellulose or fiberglass so some homeowner prefer this technique. Of course many combinations of open cell, closed cell; fiberglass, and cellulose can be used.