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Cost To Seal A Basement or Foundation

A damp or wet basement requires immediate attention to maintain the structural integrity of your home. Start by identifying the source of the moisture. One common cause is clogged or misplaced gutters and downspouts. You can redirect downspouts, clear debris or install gutters to keep water away from the foundation. Gutter costs depend on the size of the home and can be $300 or more.

National Seal a Basement or Foundation Costs

Cost data is based on actual project costs as reported by ImproveNet members.

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Average reported cost

based on 1899 cost profiles


Minimum cost


Maximum cost

Most homeowners spent between:




National Seal a Basement or Foundation Costs
Average reported cost $3,572
Number of Cost Profiles 1899 cost profiles
Minimum reported cost $55
Maximum reported cost $9,000
Most homeowners spent between: $2,475 to $4,207

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If condensation in the basement is the problem, poor ventilation may be the culprit. Install a dehumidifier and be sure to insulate water pipes. Dehumidifiers cost approximately $250, and pipe insulation may cost about $100. Another common cause of water in the basement is window wells that collect water. Installing covers on window wells instantly eliminates this problem.

Seal a basement or foundation if water is coming through leaks or cracks. Many sealing solutions are DIY projects, but some require professional installation. Start by removing any crumbling concrete and repair all cracks in the walls and floors. Use masonry caulk on cracks less than 1/8 inches wide. Caulk only costs about $10 per tube. Patch wider cracks with epoxy filler and a putty knife. Remember to patch the places where pipes and tie rods pass through the concrete. Drylok Fast Plug is effective for sealing cracks in masonry. For complex cracks or those subjected to movement, hire a professional, as DIY kits are less reliable for this level of damage.

Many homeowners can prevent water entering the basement by using sealants on smaller leaks and cracks in the wall. Sealants usually cost $12 to $40 per gallon. Apply sealers in thick layers and expect to put on at least two coats. You want to fill every pore and pinhole with the solution to create a waterproof membrane. A gallon of sealant covers about 75 square feet of wall space. Products such as Xypex apply a waterproof concrete over basement surfaces. Xypex bonds with the wall, forming a waterproof, crystalline coating as it combines with moisture. You should apply products to bare concrete or masonry walls that are free of loose material.

Serious cracks or foundation damage require professional intervention. Contractors can excavate foundation walls and apply repairs and sealants from the exterior. They might also install exterior French drains or other solutions to redirect water away from the foundation.

Last updated on May 18, 2016

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