What is the R-Value of Spray Foam Insulation?
It’s an easy thing to find if you’re talking about a traditional insulation material, but what is the R-Value for spray foam? R-Value doesn’t really mean the same thing for spray foam insulation that it does for cellulose or fiberglass.
That’s because spray foam creates an air seal that stops air movement into and out of the home. So the air you pay to treat stays right where you want it and helps you maintain a constant temperature and comfortable house.
What is R-Value? R-Value is a measurement of an insulation material’s thermal resistance. Thermal resistance is the ability to resist heat transfer or loss through conduction. Basically, if a warm or hot material comes in contact with a cold material, the heat is transferred to the cooler surface. This means the insulation material’s ability to resist heat transfer through conduction – its thermal resistance. Fiberglass and cellulose only work to prevent conduction, while spray foam works to stop conduction and convection, or air movement.
The R-Value for spray foam insulation can vary depending on the product, manufacturer, and other variables. Open cell spray foam insulation is R-3.6 to R-3.9 per inch. This R-Value is normal for open cell spray foam. Closed cell spray foam insulation is R-6 to R-7 per inch. The type of foam insulation affects the R-Value just in how they are made up. Open cell is a lighter material, so the R-Value is lower, while closed cell is thicker and denser so the R-Value is higher. This is because it takes longer for heat to transfer through the closed cell spray foam due to its denser composition.
Spray foam and the air seal it creates is what makes it a premium insulation material, not the numbers. The air seal created by foam insulation keeps air from moving freely into and out of the house. It works to help maintain a constant temperature, which in turn helps your HVAC system work less.