Waterproofing costs

Waterproofing quotes vary more than almost any other home trade, because two contractors can legitimately propose completely different work for the same wet basement. That is why an average is close to useless on its own. Price the method, not the job.

Published 2026 ranges: waterproof paint and sealants $1-$8 per square foot; interior perimeter drain $40-$120 per linear foot; epoxy injection $250-$1,000 per crack; vapor barrier $1,500-$4,000; dehumidifier installation $1,000-$2,800; exterior French drain $10-$100 per linear foot; soil regrading $500-$3,000; sodium bentonite exterior waterproofing $2-$5 per square foot (Fixr). Sump pump installation typically lands at $800-$2,000 with an average near $1,400; a battery backup adds $150-$2,000 and a replacement pump alone is $350-$1,000 (Fixr).

As whole-project figures, HomeCostLab puts interior systems at $2,000-$7,000, an interior French drain at $3,000-$6,000, exterior waterproofing at $5,000-$15,000, and calls interior French drain plus sump pump the most cost-effective combination at $4,000-$8,000 total.

The biggest cost driver is access. Exterior work means digging to the footing. A deck, a driveway, mature landscaping or a neighbor's wall three feet away can double the excavation line. Ask specifically what it costs to remove and restore whatever is in the way, and get it in the written quote — restoration is where surprise invoices come from.

How to choose

Get three quotes, and make them comparable

Ask every contractor to price the same scope in linear feet and to list the pump model, drain pipe type and discharge location. Lump-sum 'basement system' pricing hides everything.

Question anything much cheaper

A quote far below the others usually means less linear footage, a cheaper pump, or no discharge line. Compare line items, not totals.

Don't pay a large deposit

Materials deposits are normal. Handing over most of the money before work starts is not.

Price the cheap fixes separately

Regrading at $500-$3,000 and downspout extensions are separate line items for a reason. Ask what happens if you do only those first.

Budget for restoration

Concrete patching, landscaping and finished-wall repair after the work are frequently excluded. Ask directly whether they are in the number.