Basement costs
Waterproofing, interior wall treatment and drainage — priced by method, with what each one actually solves stated plainly.
Basement Waterproofing Cost
$2,000–$15,000typical projectInterior drainage against exterior excavation — three times the price, and what that buys.
Waterproofing Basement Walls From the Inside
$500–$7,000interior wall treatmentWhat sealants, membranes and interior drainage each fix, and what none of them fix.
French Drain Cost
$2,500–$12,000typical installationPer linear foot, inside or out. Plus when a drain is the wrong purchase entirely.
Timing tells you the source
Water that appears within an hour of rain starting is surface water — roof runoff, grading, a patio sloping the wrong way. It is the cheapest category to fix and the one most often mistaken for something worse.
Water that appears a day after rain, or that is present regardless of the weather, is groundwater under hydrostatic pressure. Nothing applied to the inside face of the wall will stop it; it needs somewhere to drain to, which is what a drainage system and sump pump provide.
Common questions
- What does fixing a wet basement cost?
- Between $600 and $25,000, depending entirely on the source. Gutter and grading work is $600 to $4,000. Interior drainage with a sump pump is $4,000 to $12,000. Exterior excavation and membrane is $10,000 to $25,000.
- What should I do before getting waterproofing quotes?
- Extend every downspout six feet from the foundation, clear the gutters, and check that the ground falls away from the house over the first ten feet. This costs a few hundred dollars and resolves a large share of wet basements. Any quote gathered before doing it is pricing a problem that may not exist.
- Is interior drainage as good as exterior?
- Not as complete, but proportionate for most homes. Exterior work stops water reaching the foundation and protects the structure itself. Interior drainage collects water that has already arrived and pumps it away, successfully, at roughly a third of the cost.
National 2026 figures, published as ranges. Reckon Home does not sell, broker or perform this work.