Basement waterproofing cost: what each fix costs and what's in the price

How much basement waterproofing costs

Published national prices, installed:

Source: HomeGuide, updated January 23, 2026. These are installed prices, so they don’t split materials and labor. They’re national figures, not prices from my own jobs. Your location, the size of your basement and what has to be moved out of the way can put your price well above or below these numbers.

Typical installed cost, cheapest fix first

• Replace downspouts$220–$625
• Crack injection, per crack$250–$800+
• Sump pump, installed$600–$2,500+
• Regrade around the house$1,000–$5,000
• Interior French drain$4,000–$17,000
• Interior waterproofing system$6,000–$12,000
• Exterior waterproofing$10,000–$18,000

$100$1,000$10,000

Start with the cheap fixes outside

Most of the water I see in basements is surface water: roof water discharged next to the foundation, or a yard that slopes toward the house. If water only shows up when it rains hard, and it’s at one corner or near a downspout, start there. Extend the downspout to a spot where discharge is allowed and regrade the yard away from the foundation. Then see whether you still have a problem after a few real storms.

That wouldn’t work in a basement with steady hydrostatic pressure, or with water coming in along the whole joint between the wall and the floor. Our guide to water in the basement helps you work out which one you have, and yard grading and downspout drainage cover the outside fixes.

Interior basement waterproofing cost

An interior system collects the water that gets into the basement and pumps it out. Typically, a channel is cut in the floor along the walls, a perforated drain line goes into a bed of gravel and the concrete is patched. The drain line runs to a sealed sump pit with a pump. A dimple membrane may also go on the walls. HomeGuide puts most interior jobs at $6,000 to $12,000, and an interior French drain at $4,000 to $17,000.

I don’t compare interior drains by linear feet alone. I look at how much concrete has to be cut, whether steps or finished walls have to come out, how the water will be discharged and who’s providing power to the pump. Those are the things that move the price.

Exterior waterproofing cost

Exterior waterproofing means digging down to the bottom of the foundation, cleaning the wall, applying a membrane or coating, installing a drain at the footing and backfilling. HomeGuide puts it at $10,000 to $18,000 on average, with exterior French drains at $30 to $90 per linear foot and membranes at $4 to $7 per square foot. Driveways, steps, decks and landscaping against the foundation raise the price. Our guide to interior vs. exterior waterproofing explains when the exterior is worth it.

Crack injection and sealers

A leaking crack can often be injected from inside the basement for $250 to $800 or more per crack. That fixes the crack, not other places that may be leaking. Waterproof paint and sealers cost $2 to $10 per square foot. They can help with dampness on the walls, but they won’t hold back water under pressure. If the foundation is still moving, injecting a crack doesn’t stop the movement: see foundation cracks.

What raises the price

• Extras that show up late: a new dedicated circuit for the pump, moving the discharge, drilling through the wall, lifting steps, fixing finished floors and walls, removing damaged material, debris and dump fees, permits.
• What’s in the ground: roots, rock, buried lines and digging by hand where a machine can’t reach.
• The outside: fixing the downspouts and putting the landscaping back after drains or grading ($300 to $1,000 or more for landscaping, per HomeGuide).

Reading a waterproofing quote

If you get a quote for a “complete system,” ask for a drawing and the details: how many feet of drain, the size of the drain line and the pump, whether there’s a check valve and where the water will be discharged. Some towns don’t allow sump pumps to discharge into the sanitary sewer.

Read the warranty. I want to know which area it covers and what it covers: “leaks through this joint” and “a dry basement forever” are two different things. Check what maintenance you’re expected to do, whether the pump is covered, what happens during a power outage, whether labor is covered and whether the warranty transfers to the next owner. I don’t trust warranties that exclude anything related to rain, groundwater, outages or drainage changes without saying what they do cover.