Basement waterproofing ranges from a few hundred dollars of sealant to a five-figure excavation, and the right fix depends on where the water comes from. Paying for an expensive system when gutters are the cause, or paying for paint when water is coming through the floor, wastes money both ways. This guide lays out what named sources report for each method and where they disagree.
Updated November 2026
Overall basement waterproofing cost
All figures are typical ranges reported by the named sources on the dates shown, in US dollars. They are not quotes. Get at least three written estimates for your own project.
| Measure | Typical range | Source and date |
|---|---|---|
| National range | $3,000 to $10,000, typical about $5,000, up to $20,000 | Fixr, updated February 2026 |
| Per square foot | $3 to $10 | Fixr, February 2026 |
| Interior systems | Average $3,000 (range $2,000 to $6,000) | This Old House, page dated March 2026 (citing Homewyse and Angi) |
| Exterior systems | Average $7,000 (range $7,000 to $15,000) | This Old House, March 2026 |
| Interior plus exterior | $8,000 to $18,000 | This Old House, March 2026 |
| Full exterior excavation with drains and membranes | About $20,000 or more | This Old House, March 2026 |
Fixr and This Old House broadly agree: most jobs fall between a few thousand dollars and about $10,000, with exterior excavation at the top. Exterior work costs more because crews dig down to the foundation, apply a membrane, install drainage and backfill.
Cost by method and component
| Method or component | Fixr (Feb 2026) | This Old House (Mar 2026) |
|---|---|---|
| Waterproof paint or sealant | $1 to $8 per sq ft | $1 to $8 per sq ft |
| Epoxy crack injection | $250 to $1,000 per crack | $800 to $1,500 per crack |
| Interior perimeter drain | $40 to $120 per linear ft | $60 to $120 per linear ft (interior drainage) |
| Sump pump | $600 to $2,500 | $1,200 to $2,500 (installation) |
| Vapor barrier | $1,500 to $4,000 | $1,500 to $3,000 (full coverage) |
| French drain (exterior) | $10 to $100 per linear ft | $10 to $100 per linear ft |
| Damp proofing | $3 to $6 per sq ft | not listed |
| Sodium bentonite waterproofing | $2 to $5 per sq ft | not listed |
| Gutters and downspouts | $3 to $30 per linear ft | not listed |
| Dehumidifier installation | $1,000 to $2,800 | not listed |
The sources disagree most on epoxy crack injection: $250 to $1,000 per crack on one page and $800 to $1,500 on the other. Ask a contractor whether a quote is per crack or per linear foot of crack, and whether it includes structural repair. Fixr also lists related costs: permits at $75 to $500, mold remediation starting at $500 to $1,500 and reaching $6,000, and structural damage repair at $2,500 to $25,000. Labor is around $200 per hour on both pages.
Match the fix to the cause
- Damp walls, no standing water: sealants, damp proofing or a dehumidifier may be enough. Sealants are usually the least expensive option; Fixr notes that epoxy can cost up to five times as much as acrylic.
- Water entering at the wall-floor joint or rising through the slab: an interior perimeter drain and sump pump are the usual answer.
- Water pressing against the outside of the wall: exterior waterproofing, drainage and soil grading address the cause but cost the most.
- Surface water from roof or yard: gutters, downspout extensions and regrading are the cheapest fixes and should come first. Fixr lists soil gradation at $500 to $3,000.
The U.S. Environmental Protection Agency advises fixing the water source first and drying affected items completely, and says an area of mold larger than about 10 square feet or significant water damage calls for professional guidance. Cosmetic fixes that skip the water source tend to fail.
What drives the price
- Length of wall affected. Drains are priced per linear foot, so a perimeter system on a larger foundation costs more.
- Access and depth. Tight lots, decks and landscaping raise excavation cost.
- Soil and water table. High groundwater means a stronger pump or a backup.
- Finish work. Breaking and repouring concrete, restoring drywall and flooring add to the total. Our guides to concrete cost, drywall cost and flooring cost help budget that part.
- Warranty and brand. Transferable warranties cost more upfront.
How to save
- Clear gutters, extend downspouts at least several feet from the foundation, and slope soil away before anything else.
- Get a written diagnosis, not just a quote. Ask what is causing the water.
- Collect at least three quotes, and compare the scope: linear feet of drain, pump size, battery backup, warranty.
- Do the sealing of small cracks and painting yourself only if water is not actively entering.
- Combine work: if you will repour the floor edge for a drain, finish the basement afterward, not before.
Keep records of the work; they matter when you sell the house.
Frequently asked questions
How much does basement waterproofing cost?
Fixr (February 2026) reports a national range of $3,000 to $10,000, with a typical spend near $5,000 and a high end of $20,000. This Old House (March 2026) shows interior systems averaging $3,000 and exterior systems averaging $7,000.
Is interior or exterior waterproofing cheaper?
Interior systems are cheaper in both sources. Exterior waterproofing requires excavation, so it costs more but addresses water at the wall.
How much does a sump pump cost to install?
Fixr lists $600 to $2,500 and This Old House lists $1,200 to $2,500 for installation (2026 pages).
Can I fix a wet basement for less than $1,000?
Sometimes. Gutter and grading fixes, crack sealing and paint can be inexpensive, but only if the water source is surface runoff or minor seepage. Repeated leaks usually need drainage.