How to Glue a Foam Board to Concrete

Use construction-grade adhesive to get the job done.

Rigid foam insulation board is commonly used to insulate foundations and basements. Its closed-cell construction makes it ideal for exterior insulation as it will not be easily permeated by moisture and break down as will fiberglass or other forms of insulation. Installation is easy, all you need is a construction grade adhesive to glue foam board to concrete and then you are ready to backfill or attach your exterior siding.

Things You'll Need

• Stiff brush
• Rigid foam insulation
• Box knife
• Construction-grade adhesive
• Caulking gun

Instructions

1. Clean the concrete surface of dirt and dust using a dry, stiff brush.

2. Place your foam board against the concrete and make sure it will fit the area. Trim the board with a box knife if necessary. Remove the foam board.

3. Apply construction grade adhesive to the foam board in a squiggle pattern, like a repeated sideways "S," making sure you go from top to bottom of the board and from end to end. Some adhesives are available in squeeze tubes. Others require a caulking gun.

4. Press the board against the concrete and hold in it position for one to two minutes to allow the adhesive to begin to set. Repeat these steps for each piece of foam board.

Tips & Warnings

• Lay out the foam board along the foundation before you begin to glue. This will make the process faster as you will not have to keep stopping to get more board.

• Foam board insulation is highly flammable and releases a toxic smoke when burned. Ensure that no open-flame sources are used near the board after it is installed.

References

• Art-Tec: Insulating Foundations

Resources

• U.S. Dept of Energy: Foam Board Insulation