Spray Foam Cost Table
Open Cell Spray Foam Along The Roof Deck
Open cell spray foam expands 100 times its original size and fills the cracks and crevices stopping air leaks and has an R-value of 3.7 per inch. Open cell spray foam is not recommended in cold climates but is perfect for hot, dry climates like southern Arizona where we do not have to worry about humidity. In Arizona homes, open cell spray foam is ideal for single story homes with greater attic square footage than two story attics. We like to remove the existing insulation from the attic floor before the spray foam is installed because it prevents the build-up and trapping of heat with the existing insulation left in place. 6” of open cell spray foam is typically applied to the attic rafters to achieve a R-value of R-22.2. Open cell spray foam can be applied thicker to a total depth of 8” to get an R-value of R-29.6.