Sprayed Foam Insulation is a foam product that, when sprayed into wall cavities, expands to fill the cavity and provide insulation. The foam material that is usually used in sprayed foam insulation is polyurethane which consists of a multi-ingredient chemical formulation. Other additives such as flame retardants are also be added to the foam formulation. Although, not very common, color can also be added.
In addition to using spray foam as an insulating material, the foam can also act as an air sealing product for residential wall and ceiling cavities. The insulation is sprayed, via special equipment, into wall cavities and expands to fill all the nooks and crannies in a wall cavity. Excess foam is scraped off the studs to form a uniform wall cavity. Spray foam insulation makes it easy to completely fill wall cavities with insulation and to perform air sealing in the same step.
One of the advantages of sprayed foam insulation is that the foam completely fills the wall cavities which greatly reduce air infiltration through cavities and air circulation within cavities. Moreover, sprayed foam insulation may eliminate the need for a vapor barrier, but check with your local building department on the need of a vapor barrier. To find out what vapor barrier is, read this article, vapor barrier.
Sprayed foam insulation can also be combined with other types of insulation, for example, fiberglass batt, to reduce cost. For instance, you can combine a layer of foam with other types of insulation in wall cavities to achieve air sealing and energy efficiency at a reduced cost. Some contractors spray a one-inch layer of closed-cell foam into cavities and finishes with fiberglass batt insulation.
There are two types of spray foam: open-cell (isocyanurate) and closed cell (polyurethane). The closed cell foams typically have a higher R-value than open-cell foam.
Sprayed foam insulation is applied as a liquid which contains a polymer (such as polyurethane or modified urethane) and a foaming agent. The liquid is sprayed through a nozzle into wall, ceiling, and floor cavities where it expands to fill every nook and cranny. Because it expands into tight areas, sprayed foam is ideal for insulating steel framing and around outlets. By acting as a wind and air barrier, it often eliminates the need for separate air-tightness detailing which can increase energy efficiency and allow downsizing of the heating and cooling system equipment. In addition, most foam insulation products have a higher R-value per inch than fiberglass batt insulation. Sprayed foam insulation does not shrink, sag, settle, or biodegrade.
In conclusion, sprayed foam insulation is indeed superior to conventional insulation such as fiberglass batt. But the downside is it comes with higher installation and materials prices. But in the long run, the return on investment will surely be justified in terms of lower utilities cost and increase in the value of the houses.
Here is an excellent video that shows how sprayed foam insulation is installed.
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