Basement & foundation waterproofing: methods and cost

Signs you may need foundation waterproofing

• Water on the floor after heavy rain, especially along the wall-floor joint
• White mineral deposits (efflorescence) on walls
• Musty smell, mold or damp carpet
• Leaking cracks or pipe penetrations

How foundation waterproofing is done

1. Fix the outside first: gutters, downspout extensions, grading away from the house
2. Seal leaking cracks and pipe penetrations
3. Interior: drain in a trench along the walls to a sump pump
4. Exterior: excavate, membrane and drain tile at the footing
5. Add a dehumidifier and check the sump pump each year

How much foundation waterproofing costs

Interior systems are cheaper and less disruptive; exterior waterproofing stops water before it reaches the wall but means digging around the house. Coatings and sealers ($2–$10 per sq ft) help with dampness, not water under pressure.

Source: HomeGuide, Basement waterproofing cost (updated Jan 2026). Checked October 2026.

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Foundation leak repair cost

A single leaking crack injected from inside costs about $250–$800. When water comes in along the floor joint or through many cracks, the answer is usually an interior drain and sump pump ($4,000–$17,000 for the drain).

Sump pump installation

A sump pump costs $600–$2,500 installed. Battery backup and an alarm are worth asking for: pumps fail most often during storms and power cuts.

Before you hire

• Start with gutters, downspouts and grading: they're cheap and often fix the problem
• Ask whether the system has a battery backup sump pump
• Ask for the warranty terms (dry basement, or only the system)
• If a wall is bowing or cracked structurally, repair that first

Permits, codes and licensing

Contractor licensing is set by each state, and some leave it to cities or counties. Some states license this work at state level (for example the CSLB in California, the Registrar of Contractors in Arizona or the DBPR in Florida); others only require registration or local licenses. Check the license or registration number on your state's or city's public lookup before you pay a deposit, and ask for proof of liability insurance.

Companies that offer foundation waterproofing

1,204 companies in the directory name this repair on their own website (the quote is on each company page); they are listed first in each state. Another 103 are companies that usually offer it but don't say so online – confirm when you call.