How to Prep a Wall for Polyurethane Foam Injection

Polyurethane foam injection is a repair method used to fill in cracks that may develop in masonry walls. The foam fills the cracks, sealing them off to prevent moisture flow and to prevent the crack from expanding. It’s quick and simple to apply, with no drilling necessary. Before you can inject the foam, however, the wall must be properly prepared. This preparation begins with cleaning the cracks and extends to the mounting of plastic ports over the crack, which serves as the injection locations for the foam.

Wire bristle brush
Plastic foam injection ports
Epoxy paste
Paintbrush
Putty knife

Instructions

- 1
  Clean out the cracks in the walls with a wire bristle brush to remove any dirt that would interfere with the polyurethane foam injection patch.
- 2
  Mount the injection ports to the walls to provide a method for injecting the foam into the cracks. Cover the base of the plastic ports with epoxy paste and then press the port over the crack with the port opening centered onto the crack. Space the ports along the length of the crack with an inch of space between each port, for every inch of wall thickness.
- 3
  Cover the crack with a thin layer of the epoxy paste, using a putty knife to spread the paste. This layer will seal the crack, keeping the foam inside as you inject it into the ports. Allow the paste to cure for 45 minutes.

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