Can you use spray foam on attic floor?
(Source: Building Science Corporation.) One technique that can both increase attic insulation and air seal the attic is to apply a layer of spray foam to the attic floor, then to install additional blown-in or batt insulation to meet or exceed insulation R-value requirements.
Can you use closed cell spray foam in attic?
The first thing to realize is both spray foams create an air seal, it really just comes down to what is a better fit for your project. In most cases, we recommend the open cell spray foam on the attic flat and roof deck, but there are instances where the closed cell is the better option.
Is spray foam insulation good for attics?
Closed-cell spray foam is a better choice for keeping subfloor moisture at optimal levels, while open-cell spray foam is a better choice for walls and attics, because it allows homes to “breathe.”
Can I use rigid foam insulation in attic floor?
You can use rigid foam panels or do as Tom Silva does with nearly all houses these days: Hire a pro to install spray foam insulation. Foam blocks airflow needs no vapor barrier and has a higher R-value per inch than loose fill or batts, so you’ll get more protection with less depth.
How thick should spray foam be in attic?
Now generically speaking, we usually recommend open cell spray foam to be 6- to 10-inches on a roof deck or ceiling and 3-inches in the walls. Closed cell spray foam should be 4- to 5- inches on the ceiling and 2- to 3-inches in the walls.
Is closed cell spray foam worth the money?
Closed-cell spray foam is the king of the insulations when it comes to both R-value per inch and cost. Nothing else comes close, really. Unlike its open-cell cousin, closed-cell spray foam is not vapor permeable and will not hold water. This makes it an excellent option in case of water intrusion.
How many inches of spray foam do I need in my attic?
Should I insulate my attic floor or ceiling?
roof insulation is no-contest. The floor wins every time. Insulating the floor is standard practice for an unfinished attic space. The exception to this rule takes place when families opt to convert an unfinished attic space into something usable or livable.
What insulation should I use for my attic floor?
There are three common types of insulation used to insulate attic floors: fiberglass batts, blown-in fiberglass, and cellulose. Cellulose is the best choice. The second-best choice is blown-in fiberglass. The worst choice is fiberglass batts.
Can rigid foam insulation be left exposed in attic?
Q: Can it be used in a basement or attic? Yes, it’s a great interior insulation solution for both the basement and attic.
What is the R-value of 4 inches of closed cell foam?
This microscopic difference in the two products creates a dramatic difference in performance. Closed cell spray foam has an R-value of R-7 per inch. In comparison, open cell spray foam has an R-value of R-3.8 per inch. Additionally, the materials have decidedly different densities.
How many inches of closed cell foam do I need in attic?
Does closed cell foam need a vapor barrier?
Closed-cell spray foam insulation, on the other hand, is completely moisture-resistant. Because it creates a moisture barrier on its own, there is no need to install a separate vapor barrier as long as a sufficient quantity of insulation has been implemented—typically around 1.5 inches thick.
Does attic floor need vapor barrier?
In hot-dry climates a vapor retarder should also not be installed, but attics can be vented. All attics — vented or unvented — should have an air barrier (a properly detailed airtight drywall ceiling, for example) regardless of climate.
What type of spray foam insulation is best for your attic?
When opting for the sealed attic, it’s really the closed cell spray foam that is more desirable and nearly mandatory. The closed cells create an air impermeable membrane that serves as a vapor, air, and moisture barrier. Closed cell spray foam has an R-value approaching 6.5 per inch or higher.
How do you air seal an attic with spray foam?
One technique that can both increase attic insulation and air seal the attic is to apply a layer of spray foam to the attic floor, then to install additional blown-in or batt insulation to meet or exceed insulation R-value requirements. Closed-cell spray foam (ccSPF) is the preferred product for this air barrier application.
Can you put spray foam insulation on a roof deck?
Even if a homeowner were to apply spray foam to a roof deck after the fact, the common conception might be that the insulation already on the attic floor, “doesn’t hurt anything.” While it would seem that the more thermal barrier in a house the better, leaving the attic floor insulation in may be doing more harm than good.
Can spray foam insulation stop condensation?
With spray foam creating a barrier from the roof, the plan is that the two different temperatures of air never meet – and thus do not create condensation. The first concern would be that unvented attics get incredibly hot during the Summer, as even spaces with ventilation are scorching during the warmer months.