Cracks in the Foundation: Epoxies Vs. Polyurethanes
By Damon Peter Rallis
Given enough time, foundation walls will eventually crack and while there are a range of products designed specifically for concrete repair, there are generally two main types: epoxies and polyurethanes. While both will do the trick, the answer lies in what you need to achieve when repairing the crack.
For example, epoxy works best when you are attempting to repair a crack that is structural in nature, because the area needs to be just as strong as the concrete that surrounds it and epoxies offer incredible strength. There are a wide range of epoxies for crack repair and the type you choose will depend solely on the width of the crack. Use an epoxy with a thin viscosity for smaller cracks and a thicker viscosity for larger cracks. Keep in mind, however, that epoxies are slow to harden, but they are the only type of crack repair material to use when you are dealing with a structural crack.
For cracks that are not structural in nature, but must be repaired to prevent moisture and leakage from seeping through, a polyurethane product is the right choice. Although they do not offer the compressive strength of an epoxy, they are an effective and quick solution for properly sealing a crack that could potentially leak. Polyurethane foams, injected directly into a crack, harden rather quickly and create the protective barrier necessary for such repairs.
There are an array of polyurethane and epoxy products on the market today to help repair virtually any foundation crack, but it is important to recognize exactly what it is you need to achieve (structural integrity or leakage prevention) before you determine the base material you should use.