Cracks in poured concrete foundation walls are very common. The cracks usually develop as a result of shrinkage that occurs when concrete cures. Shrinkage cracks typically occur within the first several years following construction. There can be small changes in the width of these cracks due to changes in temperature or moisture content in the concrete, but this amount of movement is very small.
Cracking or movement can also occur as a result of foundation settlement or lateral pressure exerted on a foundation wall. This type of movement is much less common with poured concrete foundation walls.
Cracks in poured concrete foundation walls typically do not need to be repaired for structural reasons, but this cannot be stated with certainty without evaluating conditions. If repairs are needed for structural reasons, epoxy injection is a common cost-effective process. This process involves pumping a liquid epoxy resin into the crack. The crack is first sealed at the surface with a paste type epoxy and injection ports are also glued to the surface. The epoxy is then pumped into the wall under pressure so that it penetrates deeply into the crack. When a crack is properly repaired using epoxy injection the crack is stronger than the concrete.
Epoxy injection is sometimes used to repair cracks to prevent water penetration. While this can be an effective repair, it is typically not the best material to use for control of water penetration. Because of the potential for expansion or contraction of the foundation wall the concrete sometimes cracks at another location. This most commonly occurs when a crack has been repaired before all curing shrinkage has occurred.
The most common reason to repair cracks in poured concrete foundation walls is to control water penetration. In these cases polyurethane injection is typically the preferred method of repair because polyurethane remains flexible after it cures. Polyurethane can often be used to seal actively leaking cracks. While this is often a cost-effective method of repairing cracks, proper repairs can involve the use of various different materials or methods.
You may wonder whether a crack can be repaired when a previous repair failed to stop water penetration. In many cases the answer is yes, but injecting a crack that was previously patched or injected is usually more difficult and requires good workmanship.
Can a homeowner repair cracks themselves? Possibly, but without the proper equipment, materials, and knowledge, many such repairs fail. This makes proper repairs more difficult. In addition, due to the expensive of the materials used there is often little cost savings.
Building Consultants, Inc. can evaluate and repair foundation wall cracks, whether for structural purposes or to control water penetration.