Tips for Attaching Foamboard to Brick Walls

Many older homes are built on brick or stone foundation walls and can be difficult to insulate during crawl space encapsulation. In this article, we discuss tips for attaching foamboard to brick or stone foundation walls.

Butyl Tape Can Help Attach Foamboard to Brick

Using 2-sided foundation butyl tape is a great way to assist in securing foamboard during crawl space insulation. We don’t recommend butyl tape alone to hold up the foamboard. Mixing butyl tape with spray foam is a great way to create a permanent seal. The spray foam needs time to cure, and the butyl tape can keep the foamboard in place during this process. Of course, you can hold the foamboard while the spray foam cures, but that takes time.

Spray Foam is an Adhesive

Did you know spray foam is often referred to as insulation, but its main purpose is an adhesive? Spray foam creates a permanent bond and cures fairly quickly. Using spray foam can be better for the foundation wall when attaching foamboard to brick or stone versus a masonry nail. Masonry nails can damage mortar joints or the wall itself. Spray foam achieves the bond but is a much slower process than nailing. You can also use masonry screws instead of spray foam, but that can be even slower.

Heavy Mortar on Brick Walls

Brick and stone walls can be uneven due to heavy mortar joints and can make crawl space insulation difficult. This makes applying foamboard difficult to foundation walls, no matter what materials were used to build the walls. Again, spray foam can help secure the foam board because more can be applied to make up for the extra mortar. Normally, on walls with heavy mortar, the butyl tape is useless, so you may have to hold the foamboard until it bonds with the spray foam.