Basement Wall Repair: Fixing Cracks

Lead Image
  • 48 hours
  • Beginner
  • 80-150
What You'll Need
Caulk gun
Liquid urethane foam
Surface seal epoxy
15 injection ports
Wire brush
Water bottle
Latex gloves
Safety glasses
Plastic drop cloth

Cracks in concrete walls are not unusual. They are often caused by construction, accidents, settling of the house, or just a natural expansion and contraction caused by fluctuating temperatures.

Most of these cracks are not serious enough to cause leaks. Others, though they may look small, can penetrate through the thickness of the wall and allow water to enter your basement. When that happens, you need to repair these leaking cracks if you want to keep water out of your basement. You may also want to repair unsightly cracks if you convert the space into a living area. Although repair of these cracks can be a challenge, you should be able to repair them if you have the right materials and guidance. The five steps below will guide you through repairing your basement wall cracks.

WARNING: This DIY task requires using epoxy and urethane products, which can both be toxic especially for people with skin or respirator conditions. Be sure to wear work gloves, long-sleeved clothes and a face mask will performing this task.

Step 1 - Remove Debris

Remove debris, dirt, loose concrete particles, and old paint with a stiff wire brush. If you are unable to remove the paint around the crack with the wire brush, use paint remover. You may need to use a softer brush to clean the surface of any dust or loose dirt. Sandpaper can also help with this task.

Step 2 - Apply Surface Sealer

After mixing ½ cup of a surface seal, place a bead of it at the bottom of an injection port and position the port over the crack, starting at the crack's lowest point. Don't cover the crack with the sealer.

Attach a port every six inches along the crack. Allow the epoxy on the ports 10 minutes to activate, then cover the entire crack with epoxy and let it cure for another 60 minutes. You'll know it's cured when you are unable to scratch it with your fingernail.

Step 3 - Prepare to Inject Urethane

Use the spray bottle to apply water to the uppermost part of the crack. This water will act as a catalyst and cause the urethane, which is added later, to expand.

Locate a lock nut at the urethane cartridge top. Remove this nut, attach a mixer onto the cartridge, and re-attach the nut you have removed. Now, insert the cartridge into the caulk gun.

Step 4 - Inject the Urethane

Insert the mixer into the first injection port and begin slowly injecting the urethane. Start at the bottom of the crack and allow the urethane to fill the crack. A foam will develop from the catalytic reaction between the water and the urethane. Allow the foam to fill the crack.

Step 5 - Test the Repaired Crack

Wait 24 hours, spray a stream of water on the crack. Inspect the crack for any leaking. If the urethane has completely filled the crack, the water you sprayed onto it will not enter. Then you can smooth out the area and cover the wall without concern that the crack will leak.