Spray foam insulation is a polyurethane or polyisocyanurate material applied as a liquid that expands and hardens to seal gaps, cavities, and thermal bridges in building envelopes. It provides both insulation and air sealing in a single application, achieving R-values between R-3.5 and R-6.5 per inch depending on foam type. This dual functionality reduces energy loss and prevents infiltration that typical batt insulation cannot address.
Types and Performance
Open-cell spray foam offers R-3.5 to R-3.8 per inch with moisture permeability, making it suitable for interior applications. Closed-cell spray foam delivers R-6 to R-6.5 per inch with excellent moisture resistance and structural rigidity, preferred for below-grade and exterior locations. Closed-cell requires thinner installation depths to meet code requirements, reducing material volume needed.
Installation and Benefits
Professional application requires trained technicians using specialized equipment. Spray foam expands 30 to 60 times its liquid volume, filling irregular cavities that rigid materials cannot access. It provides superior air sealing at R-value equivalent to 5.5 to 7 inches of fiberglass batt, delivering measurable energy savings and improved comfort by eliminating thermal bridging and air leakage.