First used in roofing systems in the 1960s, spray polyurethane foam (SPF) is emerging as an important component of many high-performance buildings. The physical properties of SPF don't change much over time, and with proper maintenance, which may include repairs and recoating, an SPF roof can last as long as the building does. SPF has high compressive strength (40 to more than 60 pounds per square inch), and closed-cell foam can increase resistance to wind uplift when it's applied to the underside of the roof deck. High thermal performance (more than R-6 per inch) make SPF valuable in net-zero energy buildings, which are designed to produce as much energy as they use on an annual basis.

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