What Is the R-Value of Foam Board Insulation?

Foam board insulation R-value varies based on type but is anywhere from 3.6 per inch of insulation thickness to 8.0.

Types of Foam Board Insulation

Before we can delve into the respective R-values of foam board insulation, we have to talk about the types of foam board.

1. Polyurethane

Foam board constructed of polyurethane is known for its sound-insulating properties. 

2. Polyisocyanurate

Polyisocyanurate is its own form of insulation. Polyisocyanurate is only available in one form, rigid foam boards.

3. Extruded Polystyrene Foam

Comprised of additives and plastic resin that is fed into a die, the foam will expand while it’s cooling.

4. Expanded Polystyrene Foam

Expanded polystyrene foam won’t develop bacteria, a benefit that extruded polystyrene also has. 

Where do you buy Foam Board Insulation?

Buy Foam Board Insulation

The sheets are usually in 4x8ft cutouts rectangle sizes (pretty big) – but bring or buy a basic utility knife with you to cut it up in the store if you need to fit small pieces in your car.