How to Choose Foam Insulation Thickness

What You'll Need
Foam boards depending on needs
Purposes of foam board insulation

Choosing foam insulation thickness can be difficult if you don't know what you are looking for. Foam boards are rigid panels that are used for insulating anything in the home. Not only do they provide thermal resistance, but they also add structural strength to any part of your home. Foam board insulation reduces heat conduction.

Step 1 - Types of Foam Board

The common types of foam insulation board are polystyrene, polysiocyanurate, and polyurethane. A molded expanded polystyrene foam board is a closed-cell material that is used in everyday items such as cups, shipping materials, and are made into foam boards of insulation. Foam boards vary depending on the type of bead that is used.

Step 2 - Knowing the Difference between Bead board and Roof Boards

Foam board is manufactured at different densities, depending on the application that it is used for. Knowing how thick to choose insulation depends on its purpose. Bead board used for roofing should be dense enough to walk upon without causing damage. Wall boards used for insulation are seven times less denser than roof boards because the insulation is meant for warmth and not durability. Wall insulation boards vary in thickness from 3.8 to 4.4 inches of thickness.

Step 3 - Different Facings of a MEPS Foam Board

MEPS foam boards come in a number of facings depending on their need. Spaces can sometimes exist between these foam beads causing the absorbtion of water, so it is important to have a vapor diffusion board. This type of foam board is used for insulation for structural insulated panels, as well as insulating concrete forms.

Step 4 - Knowing the Difference between a MEPS Board and an XEPS Board

An extruded expanded polystyrene board is a closed-cell foam insulation board that are made with various chemicals to allow liquefaction. This allows for a thicker density, up to 1.5 pounds per cubic foot. The XEPS board is more expensive than the MEPS board. The R-value of the XEPS board depends upon the density of the material and runs about R-5 per inch. In addition, it is more consistent in density and has a higher compressive strength. This is the ideal insulation to use on roofs or for wall panels. It is also a good moisture absorber.

Step 5 - What Foam Insulation to Use with Space Limitations

If you have space limitations, a polyisocyanurate or polyurethane foam board should be used. Both of these types of boards offer different R-values, giving you the advantage to use a thinner foam board. They come in a variety of compressive strengths and can resist deformation and maintain its shape if subject to a heavy amount of weight. This type of insulation is good for roofing and can be used as a vapor barrier.

Foam board insulation depends on installation. You will need to contact a contractor to receive the R-value. This R-value will determine how thick your insulation foam board should be.