Spray foam works wonders in Arizona’s extreme temperatures. Spray foam applied in Phoenix will bring your attic into conditioned space so all the ductwork and air handlers no longer need to work against 150 degree attic temperature. The first 90 seconds the AC is running will actually put out cool air during the summer rather than preheated air from ductwork that has been baking in the attic. Spray foam also acts as an air barrier, effectively sealing up your home from dust and allergens. Air sealing can be done manually by removing the insulation and sealing attic penetrations, canned lights, and top plates, but they are sometimes difficult to find in hard-to-reach-spots and must be done while balancing from stud-to-stud.
Spray foam insulation has the highest R-value and is more effective at blocking the heat than cellulose and fiberglass. There are two types of spray foam, open cell and closed cell. Both types serve as an air barrier helping to seal up penetrations and keep conditioned air inside your home while keeping dust and pollen out (see article on How to Stop Home Allergens).
Open cell foam expands much more than closed cell foam and therefore provides better sound blockage than closed cell foam. However, open cell foam has an R-value of R-3.6 compared to the R-6 of closed cell foam.
Closed cell foam costs more, but is has a higher R-value at R-6 per inch and is useful in tight areas without a lot of space. The closed cell spray foam does not block outside noise as well as the closed cell but it is much denser and enhances the structural integrity where installed. Closed cell foam is also an excellent vapor barrier to stop moisture from entering the home.
How Much Does Spray Foam Insulation Cost?
What Are the Health Hazards of Spray Foam Insulation?
We recommend homeowners leave their home for a 24 hour period during the application of spray foam, although many homeowners will leave only for the day, and some will choose to remain in their homes during application. During the application of spray foam risks include skin and eye irritation and respiratory problems but after a 6 hours cure period, these risks go away as long as the material has been properly prepared.
Open Cell vs Closed Cell Spray Foam
Open cell spray foam can expand up to 120 times its original volume, whereas closed cell spray foam is much denser and barely expends as all. In Phoenix we use open cell spray foam for almost all applications because of our dry climate. Open cell spray foam can meet builder's specifications in new construction walls and attics without the high cost of closed cell foam. Closed cell spray foam costs 2-3 times more than open cell spray foam and is ideal for humid climates that receive rain. This is why you'll see closed cell foam in the midwest and east coast more. It's common to see closed cell spray foam applied to the attic floor in humid climates whereas open cell spray foam is applied to the roof deck to keep our hot attics cool.
Should the Attic Floor Insulation Be Removed When Doing Spray Foam?
What is the best practice for homeowners when they are considering spray foaming their attic? In a hot dry climate like Phoenix, spray foam is worth the extra cost and is the ideal insulation method because all of our ductwork and HVAC systems are inside the attic space. We've answered this question extensively on our blog and video below.