DIY Concrete Basement Crack Repair

November 26, 2012

Concrete Cracks in Basements

Many homes that have concrete basements have foundation cracks. This is a normal situation because as the concrete cures it shrinks in volume. This shrinkage creates stresses in the concrete wall. To relieve the stress, the concrete cracks. The most common areas for a "shrinkage crack" to occur are in the middle of a long wall, below a corner of a basement window or where the foundation wall changes height.

A large number of homes built since 1990 have their walls coated with a waterproof membrane. This waterproofing protects many cracks from leaks, but it can be defeated. Whether your home is protected by waterproofing or not, there are several ways for water to get into the basement;

Soil above the waterproofing allows water to enter above the protective waterproofing. When rains occur, water enters the crack above the waterproofing and leaks into the crack from the top. The water runs down inside the crack until it is seen on the interior surface of the basement wall as a leak.The corners of basement window openings are a common area for concrete to crack. During rains water runs off of the window and then enters the crack at the window opening corner. Again the water runs down the inside of the crack until the crack narrows and forces the water to the interior face of the basement wall.Some cracks are sufficiently wide to exceed the maximum width the waterproofing is designed to protect. In this case the waterproofing tears and leaves a gap in protection against the water. Water can enter directly into the crack and enter the basement.Foundation walls without waterproofing run a high risk of having cracks leak. Water can enter unhindered through any shrinkage cracks and appear on the interior side of the basement.

Whatever the source of the leak, homeowners wish to stop it.

DIY Concrete Basement Crack Repair Kits

Urethane foam injection used to be a process only professional repair technicians could perform. Kits with urethane foam are available for homeowners to stop water leaks in concrete basement cracks. Urethane foam liquid is injected into the crack using a common caulk gun. Once inside the crack the urethane begins to expand. This expansion forces the urethane foam all the wall through the crack. Once finished the crack will be sealed from top to bottom. Now water will remain on the outside of the basement and not leak into the basement.

Urethane Foam Injection Advantages

  1. No chiseling the foundation wall
  2. Entirely fills the crack top to bottom
  3. Fast repair performed in about 1-2 hours
  4. Little mess


  1. Concrete basements only. This repair will not work on block foundations.
  2. Surface must be dry. The interior face of the basement wall must be dry for application.

Click here for a list of our kits.


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