Estimate interior sealer, interior drain tile, exterior excavation, crawl-space encapsulation, sump pumps, and dehumidifiers. 2026 data; not a contractor bid.
| Item | Quantity | Estimated range |
|---|
Got a contractor quote? Compare it to the planning range.
What this is: a planning-range basement waterproofing calculator informed by Basement Systems / Groundworks network pricing, HomeGuide, HomeAdvisor, Homewyse, and licensed cost-estimating references.
Labor is modeled from per-unit installed rates with a crew-rate sanity check ($75-$140/crew-hr loaded billing rate), informed by BLS OEWS 47-2061 (Construction Laborers).
Last updated: May 2026. Full methodology →
| Scope | Range | Timeline |
|---|---|---|
| Interior sealer + paint (1,200 SF wall) | $3,500-$8,000 | 2-3 days |
| Crack injection (1-3 cracks) | $400-$3,500 | 1 day |
| Interior drain tile + sump (60 LF) | $5,500-$12,500 | 3-5 days |
| Exterior excavation + membrane (40 LF) | $7,000-$18,000 | 1-2 weeks |
| Crawl-space encapsulation (1,000 SF) | $7,000-$18,000 | 3-5 days |
| Sump pump system w/ battery | $1,200-$3,500 | 1 day |
| Dehumidifier install | $1,000-$3,000 | 1 day |
The two approaches solve the problem from opposite sides:
Interior is the usual choice; exterior is for severe or recurring water you can't manage from inside.
Waterproofing money is wasted if it doesn't target the actual source — diagnose first:
A foundation/waterproofing inspection ($294–$500) finds the real entry point before you spend five figures — and often the cheapest fix is outside the basement entirely. Clogged gutters and soil sloping toward the house cause a large share of "wet basement" calls and cost almost nothing to correct. Where water has been sitting against drywall, framing, or stored organics, budget for mold remediation ($1,764–$3,000) as part of the job. The cardinal rule: waterproofing that doesn't address the source just relocates the problem.
Interior sealer / paint: $3-$8 per square foot of wall ($3,500-$8,000 for a typical 1,200 SF basement). Interior drain tile + sump (60 LF): $5,500-$12,500. Exterior excavation + membrane (40 LF): $7,000-$18,000. Crawl-space encapsulation (1,000 SF): $7,000-$18,000. Sump pump install: $1,200-$3,500.
Interior drain tile collects water that's already entered through the wall and pumps it out — cheaper, less disruptive, but doesn't fix the source. Exterior excavation seals the wall from the outside and is the most permanent fix — but you pay for the dig (often $150-$400/LF). Most homes start interior, only go exterior if interior fails or the wall is actually moving.
Reputable waterproofing companies offer 10-25 year transferable warranties on interior drain tile + sump systems and on exterior membrane work. The transferability is a real selling point at resale. Always read the warranty: most are limited to the work performed, not all water entry, and may exclude hydrostatic pressure events.
Limited mold remediation often included. Full remediation is a separate scope ($2-15k+) handled by certified IICRC mold contractors.
Sealer + paint and minor crack injection — yes for confident DIYer. Drain tile, sump, encapsulation — pro work for code, scale, and warranty.
Interior sealing is $3,500-$8,000; crack injection $400-$3,500; interior drain tile with a sump $5,500-$12,500; exterior excavation and membrane $7,000-$18,000; and crawl-space encapsulation $7,000-$18,000. The right scope depends on the water source.
Interior drain tile + sump ($5,500-$12,500) manages water that gets in and is less disruptive - the common choice. Exterior excavation + membrane ($7,000-$18,000) stops water at the wall and is the gold standard for severe cases, but it digs up the yard.
Diagnose the source before spending. Clogged gutters and soil sloping toward the house cause many wet basements and are cheap to fix ($1,764-$3,000 to regrade and extend downspouts). Beyond that it is crack injection, interior drain tile, or exterior waterproofing.
