R-value

Depending on the specific manufacturer, SPF products can have some of the highest R-values of any residential insulation. A range between 6 and 7 per inch can be expected.10

Limitations

All polyurethane foam insulations must be installed by certified installers. Safety gear and ventilation equipment are required dur­ing installation. The installation of polyurethane foam can be a messy process. Since the material adheres to any surface, extensive masking may be required on specific job conditions.

CFCs were formerly used as blowing agents but were banned from use by the Montreal Protocol, an international plan to limit the production and ultimately the release of CFCs. Currently, polyurethane foam insulation is blown with HCFCs such as HCFC – 141b, which are less threatening to the earth’s upper atmosphere but still have ozone-depleting potential. Production of this chemi­cal for use as a blowing agent is to cease by January 1, 2003. Ferrous metals should be painted with a primer prior to applica­tion of rigid polyurethane foams.

Polyurethane foams are not UV stable and can be biodegraded by both direct and indirect sunlight. If exposed for any long period of time, the finished product needs to be coated with an elastomeric coating designed to protect the SPF from sunlight. Without some type of UV protection, the foam will degrade, compromising the thermal performance. SPF typically turns from a light yellow to a dark orange or brown color after UV exposure. Eventually, the sur­face degrades into a light powder that can be eroded by wind and rain to expose the foam below, thus starting the process again. The eroded surface of the SPF appears similar to that of an eroded dry creek bed within a few years.