SPF is quickly gaining ground as a high-demand insulating material. Here’s Why.
By Matt Weber
An increasingly popular method of home insulation is Spray Polyurethane Foam, commonly called Spray Foam or SPF.
Although pioneering work on polyurethanes was conducted as far back as 1937 in Germany, it was not until the early 1970’s that 2-pound/cu. ft. closed-cell foams were used in the U.S. for perimeter wall insulation. In the mid 1990’s, 1/2-pound/cu. ft. open-cell foams were brought into the market for interior wall insulation as seen in many of today’s new homes.
Spray Foam is a spray-applied insulating foam plastic that is installed as a liquid and then expands many times its original size. As home insulation, the concept is similar to living inside a sealed Styro Foam cooler. The foam can be adjusted to have many different physical properties depending on its intended use. For example, the same basic raw materials that can make insulation foam semi-rigid and soft to the touch also creates high-density roofing foam that withstands foot traffic and water. Specialized equipment is used to apply the Spray Foam, and proper training is important in order to get the best results.
As an insulating material SPF can provide high levels of R-value, while providing air barriers and moisture control in buildings. For roofing, spray polyurethane foam insulates and eliminates thermal bridging through fasteners or gaps in decking.
Spray foam is available in two versions; low-density/open-cell SPF and medium-density/closed-cell SPF. The low-density/open-cell SPF refers to a generic Spray foam that weighs between 0.4 to 0.6 lbs. per cubic foot when fully cured. It is spray-applied as a liquid and expands about 100-150 times its original volume to form a semi-rigid/flexible, non-structural SPF insulation. The low-density SPF has an R-value around 3.5 per inch.
Medium-density/closed-cell SPF used in interior applications refers to spray foam that weighs between 1.5 to 2 lbs. per cu. ft. when fully cured. It is also sprayed as a liquid onto a substrate and expands about 35 to 50 times its original volume to form a rigid, structural SPF insulation with a compressive strength between 15 to 25 PSI. The SPF has an aged R-value of around 6.0 per inch.
Benefits of SPF
Spray foam offers a number of benefits for residential construction. SPF is durable, maintains its physical properties over time (won’t sag), and for the “green” thinking consumer it contributes little to the waste stream. Plus, depending on the formula and project, a single product can take the place of three or four other products, including insulation, air barriers, sealants, vapor retarders and weather barriers.
“While there is a higher upfront cost for the installation of the foam, SPF can really cut down on energy bills in the long run,” says Ron Brown of Thermetix, a professional installer of SPF systems throughout Alabama. Although the initial cost of installation could be 3 to 4 times the cost of installing standard fiberglass batts, in as few as five years the homeowner can recoup their investment and enjoy lowered utility bills throughout the life of the house. SPF also has no food value to attract insects or rodents.
“Spray foam is also helpful for people who suffer from allergies,” says Brown, explaining that the seamless, continuous layer of insulation provides superb air quality and reduces pathogen growth.
Furthermore, according to the Spray Polyurethane Foam Alliance (www.sprayfoam.org), closed-cell SPF adds structural strength by “gluing” a building together, thereby making it more resistant to racking events, such as hurricanes and high winds. SPF also reduces noise from outside by air-sealing the building.