How to Waterproof a Block Wall

Water can seep through block walls and cause damage over time.

Block walls usually make up the basement boundaries of a home. These block walls, situated against the earth, are prone to water damage. If you don't waterproof a block wall at the earliest sign of seepage, the moisture will slowly deteriorate your blocks, leading to bigger repair bills and the risk of ruining everything in your basement. Waterproofing block walls is a job that the average homeowner can do on her own, saving some money in the process.

Things You'll Need

• Wire brush
• Shop vac
• Hydraulic cement
• Waterproofing sealant
• Paintbrush or roller

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Instructions

1. Remove the water from the block walls by improving air circulation. Open the doors and windows, and hook up fans to keep the air moving. Install a dehumidifier to remove moisture from the air.

2. Clean the block wall with a wire brush to remove dirt and loose mortar. After you finish, use the brush of your shop vac to make sure the block walls are clean.

3. Inspect the block wall for any problem areas. Patch any holes and cracks that you see in the blocks with hydraulic cement. Apply the cement and allow it to cure according to manufacturer's directions.

4. Apply a waterproofing sealant on the blocks. Paint it on with a paintbrush or roller. Each waterproofing sealant has different directions for applications, so read and follow what the manufacture recommends.

5. Allow the waterproofing sealant to dry according to the label directions.

6. Inspect the blocks for areas that you may have missed or for small pin-sized holes in the surface of the paint. Repaint those areas to seal the holes and keep it waterproof.

7. Determine if you need a second coating. If after a week you still see signs of water, apply a second coat of waterproofing sealant.

References

• United Gilsonite Laboratories: Drylok Extreme Latex-Base Masonry Waterproofer
• "The Original Basement Waterproofing Handbook"; Jack Masters; 2011
• "Keeping Basements Dry"; Larry Diamond; 1980