What is spray foam?
Spray Polyurethane Foam is a cellular thermoset plastic. A thermoset plastic is a polymer that irreversibly cures to its finished state through a catalytic reaction.
Unlike thermoplastic foam, a thermoset foam cannot be melted (it burns without liquefying).
Spray foam is a combustible product.
Two types describe most of the SPF market
Spray Foam used for residential or commercial insulation is categorized into two types, “open-cell” or “closed-cell”.
Open Cell Foam
- Open-Cell insulation foam is a liquid which is spray-applied. The liquid turns to foam within two to three seconds and expands in volume about 100 times.
- Typical density is 6 to 11 kilograms per meter cubed (0.4 to 0.7 pounds per cubic foot).
- Considered “Light Density Foam”.
- R-value of 3.4 to 4.0 per inch.
- Because it is spray applied it provides a perfect air seal for the building envelope.
- Open-Cell foam is an air barrier but is not a vapour barrier.
- This foam has a soft, almost spongy feel to it because of its open cell structure.
- Used for interior applications.
- Provides excellent noise reduction.
- With Open-Cell foam the tiny cells of the foam are not completely closed. They are broken and air fills all of the “open” space inside the material.
Closed Cell Foam
- The higher density Closed-Cell spray foam insulation is a spray-applied liquid just like the Open-Cell foam, except that medium density 2 lb. only expands about 30 times its volume.
- Insulation foams typical density is 27 to 40 kilograms per meter cubed (1.7 to 2.5 pounds per cubic foot). Considered “Medium Density Foam”.
- Roofing foams typical density is 40 to 48 kilograms per meter cubed (2.5 to 3.0 pounds per cubic foot) or higher. Considered “High Density Foam”.
- Used for both interior and exterior applications.
- Qualifies as a vapor barrier at a thickness over 50mm (2 inches).
- Due to its higher density, this type of foam feels stiffer and actually adds structural value to the building.
- Closed-cell foam differs in that all of its tiny foam cells are closed and packed together. They are filled with a gas that helps the foam rise and expand and become a greater insulator.