Spray Foam Insulation 101

Spray foam Insulation has moved to the forefront of home and commercial insulation technologies in recent years. It is a significant improvement over traditional fiberglass insulating systems. By acting as a wind and air barrier, it often eliminates the need for separate air-tightness barriers. By eliminating the heat pressure associated with a non air-conditioned attic space, the spray foam system can increase energy efficiency and allow downsizing of the heating and cooling system equipment. 

Historically, the most common insulation method uses fiberglass insulation batts, which are placed between the studs and stapled into place. The drywall is then nailed over it, creating a straight wall. Although this is an acceptable method, it does not create an airtight seal, so heat can escape. 

There are several manufacturers of spray foam insulation products and each have their own formula and application techniques. Spray foam can be used as an insulating and air sealing product for residential wall and ceiling cavities. The insulation is sprayed into wall cavities and expands to fill all the gaps and spaces 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. 

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 open space. Because it expands into tight areas, sprayed foam is ideal for insulating steel and wood framing applications. Sprayed foam insulation does not shrink, sag, settle, or biodegrade and as the house expands and contracts, so will the foam insulation. This eliminates cracks and spaces for warm air to escape.

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. Open-cell spray foam is what is typically used in residential construction. Every inch of open-cell spray foam has an R value of about 3.81. Many manufacturers claim an R value per inch of about 5.9. The cost of spray foam insulation is about $1.25 per square foot at an R value of 19. More and more of the manufactures of spray foam are starting to use agricultural based materials like soy to replace a percentage of the chemicals in spray foams further placing them in the “Green” arena.