Ask Dr. Dave - September 2002
QWe install custom wood floors over a foam base. Sometimes, after installation, imperfections in the floor require us to fill voids. We want to be able to drill a small hole in the wood and inject some type of filler. However, we do not want something too strong that would bond the wood permanently to the floor.
AThe usual way of doing this is to fill the imperfections before the installation with an epoxy-based filler. However, in your case, it sounds like you need something that will be easy to inject, completely fill the void and then have a low-enough adhesive or cohesive strength not to permanently bond the wood. I would suggest that the ideal material might be a foamed polyurethane sealant of the type used to fill holes in construction projects.
These foams come in an aerosol can, which will give you the required pressure to inject the sealant. The sealant will then expand to fill the void and then cure to a solid. Don’t be discouraged if you remember using these foams several years ago when they foamed excessively. Several “low-foam” versions are now available that should give you the right amount of controlled foaming for your application. If you need to remove the wood flooring in the future, the urethane will almost certainly have a low-enough cohesive strength to break rather easily under a minimum force.