How to Repair a Cement Basement

Cracked cement floors or walls can lead to moisture leaking into your basement.

Basements have the reputation for being damp, dreary places, and cracks in cement foundations or walls lend themselves to these reputations. Concrete and cement crack naturally over time as a result of stress or temperature changes and, while small cracks will have few effects, larger ones can cause leaking and other damage. Don't ignore the cracks and chips in your basement wall and floor or, by the time you get to them, you could have a real mess on your hands.

Things You'll Need

• Safety goggles
• Cold chisel
• Hammer or mallet
• Brush or broom
• Paintbrush
• Bonding adhesive
• Patching compound or hydraulic cement
• Trowel

Instructions

1. Wear safety goggles when working with loose debris. Chisel out the damaged area with a sledgehammer and cold chisel. Remove any loose pieces and create a smooth surface around the edges of the chip or crack.

2. Clean out the damaged area with a brush, broom or compressed air. Remove all dust and debris from the area to ensure a strong bond between the cement and the repair patch.

3. Paint a thin layer of concrete bonding adhesive around the edges of the damaged area. The adhesive will help to ensure a strong bond between the patch and cement surface while the repair work dries; this can be especially important on vertical repairs, such as those in your basement walls.

4. Mix hydraulic cement or patching compound and additives as recommended by your specific product instructions. Different products will require different additives at different ratios, so follow product instructions carefully.

5. Fill in your damaged area, using a mason's trowel to apply the cement patch. Cover the edges of the crack or chip in a thin layer of the patch first, then continue to add thin layers until you have filled in the entire damaged area.

6. Scrape the flat edge of your trowel over the repair work to flatten it against the rest of the surface. Allow the repair work to dry overnight before making any other changes.

Tips & Warnings

• Cement cracks and chips will get worse over time. Address these problems as soon as you notice them to avoid potentially serious damage in the future.

• Hydraulic cement sets within two to three minutes of mixing. You must use this product very quickly, or only mix small batches at a time.

References

• Concrete Network: Concrete Patch---Repairing Cracks in Concrete
• This Old House: How to Fix a Leaky Basement Wall