Most homeowners pay $2,500–$8,200 to waterproof a basement, with a national average of about $5,200, or roughly $3–$10 per sq. ft. Sealing a single crack can cost as little as $250–$800, while a full interior drainage system runs $4,000–$17,000 and exterior excavation $10,000–$18,000 or more (Angi, HomeGuide and This Old House data, as of October 2026).
Updated October 8, 2026. Source: Angi + 2 more. National US estimates.
You may need basement waterproofing if you see water at the joint between the walls and floor, damp patches after rain, white mineral deposits (efflorescence) on the walls, a musty smell or peeling paint. The right fix depends on where the water comes from: a few leaking cracks, groundwater pushing up under the slab, or surface water draining toward the house.
This guide covers average costs by method and basement size, a line-item breakdown of a typical interior drain job, the factors that move the price and how to compare bids. If you're dealing with a single leak rather than a whole-basement problem, start with our foundation leak repair cost guide.
Average cost
Typical basement waterproofing totals from national cost guides, as of October 2026:
| Scenario | Typical range | Notes |
|---|---|---|
| Minor: seal cracks or coat walls | $250–$1,500 | Crack injection $250–$800+ per crack; sealant $1–$10 per sq. ft. |
| Moderate: partial interior drain and sump pump | $2,500–$8,200 | Most common range; national average about $5,200 |
| Full interior drainage system | $4,000–$17,000 | Perimeter drain tile tied to a sump pump |
| Exterior excavation, membrane and drain | $10,000–$18,000+ | Full exterior jobs can reach $20,000 or more |
Basement waterproofing cost by method
| Method | Typical cost | Used for |
|---|---|---|
| Waterproof paint or sealant | $1–$10 per sq. ft. | Dampness and condensation, not active leaks |
| Crack injection (epoxy or polyurethane) | $250–$1,500 per crack | Leaking cracks in poured concrete walls |
| Interior drain tile (weeping tile) | $40–$120 per linear foot | Water at the wall-floor joint, high water table |
| Sump pump installation | $600–$2,500 | Needed with any interior drain |
| Vapor barrier on walls | $1,500–$3,000 | Moisture control behind finished walls |
| Exterior drain (footing level) | $30–$90 per linear foot | Installed after excavation |
| Exterior membrane | $3–$7 per sq. ft. | Liquid or sheet membrane on excavated walls |
| Yard regrading | $500–$5,000 | Surface water flowing toward the house |
Basement waterproofing cost by size
Angi's ranges at about $3–$10 per sq. ft. of basement floor; simple sealing lands at the low end, full drainage at the high end.
| Basement size | Typical cost |
|---|---|
| 500 sq. ft. | $1,500–$5,000 |
| 750 sq. ft. | $2,300–$7,500 |
| 1,000 sq. ft. | $3,000–$10,000 |
| 1,500 sq. ft. | $4,500–$15,000 |
| 2,000 sq. ft. | $6,000–$20,000 |
Cost breakdown: materials, labor, permits and extras
Line-item estimate for installing interior drain tile along one leaking wall (about 40 linear feet) with a new sump pump, plus injecting one wall crack. Ranges are national, as of October 8, 2026.
| Cost item | Typical range | What it covers |
|---|---|---|
| Interior drain tile, installed | $1,600–$4,800 | Cutting the slab, trench, perforated pipe, gravel and new concrete; $40–$120 per linear foot |
| Sump pump and basin, installed | $600–$2,500 | Pit, pump, check valve and discharge line |
| Crack injection | $250–$800 | Epoxy or polyurethane on one leaking crack |
| Permits | $75–$500 | Required in many towns, especially for excavation or plumbing |
| Debris removal | $130–$370 | Broken concrete and soil hauled away |
| Contingency (about 10%) | $250–$700 | Extra cracks or a longer drain run |
| Estimated total | $2,900–$9,700 | Before any discounts or rebates |
Extending the drain around the whole perimeter is what pushes interior systems toward $10,000–$17,000.
What affects the price
- Interior or exterior approach. Interior systems are cheaper because there is no digging: Angi reports interior jobs average about $3,000 and extensive exterior jobs about $7,000, while HomeGuide puts full exterior waterproofing at $10,000–$18,000. Exterior work stops water at the wall; interior systems collect it and pump it out.
- Drainage system and sump pump needs. Interior drain tile costs about $40–$120 per linear foot and needs a sump pump ($600–$2,500). A battery backup adds cost but keeps the system working in a power outage; see our sump pump installation cost guide.
- Wall and floor crack repair. Each leaking crack costs about $250–$800 to inject, and up to $1,500 for long or complex cracks. Horizontal or widening cracks point to structural pressure and may need reinforcement, which is foundation repair rather than waterproofing.
- Size of the basement and linear feet of wall. Methods are priced by the square foot (sealants, membranes) or the linear foot (drains). Angi's ranges run from $1,500–$5,000 for a 500 sq. ft. basement to $6,000–$20,000 for 2,000 sq. ft.
- Soil type and water table. Clay soils and a high water table push water against the walls and up through the floor, so these homes usually need full perimeter drainage and a pump rather than sealant. HomeGuide lists soil and water table as cost factors but gives no fixed surcharge.
- Excavation and landscaping restoration. Exterior jobs pay for excavation at about $50–$200 per cubic yard, plus restoring what was dug up. Landscaping repairs run about $300–$1,000+, and decks, patios or driveways along the wall add more.
Ways to save
- Fix surface water first: clean gutters, extend downspouts at least several feet from the house and regrade soil to slope away. Downspout replacement runs about $220–$625, far less than a drain system.
- Treat the source you actually have. Paint and sealants ($1–$10 per sq. ft.) help with dampness but won't stop a leak, and paying for full excavation is overkill when one crack is the problem.
- Get at least three written quotes and compare the linear feet of drain, pump model, whether a battery backup is included and the warranty terms.
- Ask your city, county or utility whether it offers flood-mitigation or stormwater rebates for drainage work or sump pumps. Federal energy tax credits ended for improvements placed in service after December 31, 2025, so don't count on one.
- Waterproof before finishing the basement. Opening finished walls later to add a drain adds demolition and rebuild costs.
- Avoid companies that push a full system after a free inspection without explaining where the water enters; an independent home inspector or engineer can confirm the source.
Related questions people ask
How much does basement waterproofing cost?
The cost of basement waterproofing averages about $5,200, and most homeowners pay $2,500–$8,200, according to Angi. Minor fixes can cost under $1,000, while a complete system can reach $15,000 or more.
What is the cost of waterproofing a basement per square foot?
Waterproofing a basement costs about $3–$10 per sq. ft. on average. Waterproof paint and sealants run $1–$10 per sq. ft., exterior membranes $3–$7 per sq. ft., and Angi reports full waterproofing at $5–$10 per sq. ft. versus $3–$6 for damp-proofing.
How much does it cost to waterproof a basement from the inside vs. outside?
Angi reports interior waterproofing averages about $3,000, though a full interior perimeter drain with a sump pump runs $4,000–$17,000. Exterior waterproofing with excavation costs about $10,000–$18,000, and full excavation with French drains and membranes can top $20,000.
How to get an accurate quote
Ask at least three licensed, insured waterproofing contractors for written, itemized quotes after an on-site inspection. Give each the same information:
- Where and when water appears (after heavy rain, in spring, all year), and photos of stains, cracks or efflorescence.
- The basement size, wall material (poured concrete or block), and whether walls are finished or there is a sump pit already.
- What sits outside along the problem walls: driveways, patios, decks or landscaping, and where gutters discharge.
- Ask each bidder to list the method, linear feet of drain, pump model and backup, crack repairs, permits, cleanup and warranty transferability.
FAQ
Is basement waterproofing worth it?
Usually, if water gets in more than occasionally. Water damage repair costs about $1,360–$6,290 per event and mold removal $500–$3,500, so stopping recurring leaks often pays for itself, and a dry basement can be finished.
How long does basement waterproofing last?
Interior drain systems and exterior membranes are designed to last decades with maintenance. Angi suggests budgeting about $200–$400 a year for upkeep and roughly $1,000 for resealing every 5–10 years.
Does homeowners insurance cover basement waterproofing?
No. Waterproofing is considered maintenance or an improvement. Insurance may cover sudden water damage from a covered event, and sump pump backup coverage is usually a separate endorsement.
More Basement & Crawl Space costs
Related cost guides
Sources
- Angi — How Much Does Basement Waterproofing Cost? [2026 Data] (updated Jul 20, 2026). Checked October 8, 2026.
- HomeGuide — How Much Does Basement Waterproofing Cost? (2026) (Jan 23, 2026). Checked October 8, 2026.
- This Old House — How Much Does Basement Waterproofing Cost? (2026 Pricing) (updated Mar 4, 2026). Checked October 8, 2026.
Prices are estimates and vary by location and provider. See our methodology and editorial policy. Browse all foundation & water cost guides.