How much does it cost to waterproof a basement?

Basement waterproofing with our Forever Dry System runs $3,000 to $30,000 for most New England homes. The price moves with how much wall you have to protect, how wet the basement already is, and what shape the floor is in. We give you the real number after a free inspection, and you get the quote within 24 hours.

That spread covers a full system, not a patch. The Forever Dry System is full perimeter interior drainage, a sump pump sized to your basement, a 12 mil wall vapor barrier, and a dehumidifier. It is basement only, and it is 100% guaranteed to be dry for life!

Why your basement takes on water

When your house was built, the crew dug out around the foundation and then put that same soil back. That backfill is loose. It drains slow and holds water against the wall instead of carrying it away. Add a New Hampshire winter and frost heave starts pushing on the walls from the outside. Water finds the weakest path. Usually that is the floor wall joint, the seam where the slab meets the wall.

So the water you see is usually a drainage problem, not a wall problem or a crack problem. That is the part most folks get wrong.

What drives the cost

A few things move the number up or down.

How many linear feet of wall we drain. A small basement costs less than a big one. Simple math.

How wet it is. A damp corner is a smaller job than a floor that floods every spring.

Pump setup. Every Forever Dry System gets a sump pump at 1/2 hp per 120 feet of drain. A bigger basement needs more pump.

Floor condition. If the slab has to come up cleanly along the perimeter, that is labor.

We do not waterproof from the outside. Digging up the yard and tarring the wall is a poor fix. We have seen those fail in about two or three years, and then you are paying twice. The drain we put on the inside lasts. That is where the water shows up, so that is where we stop it.

You may not need the whole thing yet

Here is where we tell you to slow down. If you have one small leak from a single crack and a dry floor everywhere else, you might just need a crack injection, not a full system. See our foundation repair page for that. We will say so at the inspection. We would rather size the fix to the problem than sell you more than your basement needs.

If your wet space is a crawl space and not a basement, that is a different job too. The Forever Dry System is for basements. For a crawl space we do crawlspace encapsulation, and that price is $3,000 to $25,000.

What you get with the system

Full perimeter interior drainage moves water under the slab and out. The sump pump pushes it away from the house. The 12 mil wall vapor barrier blocks moisture coming through the block. The dehumidifier keeps the air dry so you do not grow mold.

The whole thing carries a transferable lifetime warranty. The sump pump system is covered 3 years, batteries not included. The dehumidifier is 5 years. The wall vapor barrier is 25 years. Transfer is conditional, so it stays good as long as no other contractor touches our work.

A note on power. Our backup sump is battery only. A charged backup battery can pump about 15,000 to 20,000 gallons before it runs down, roughly a residential pool’s worth of water. That is your safety net when the grid drops in a storm.

We have done dry basements for 5,000+ homeowners across New England. We are BBB A+ accredited and rated 4.9 on Google across 250 reviews. Licensed and insured, OSHA certified, and we self perform the work with our own crew.

Financing is available through Hearth, subject to approval. We make nothing on it. It is just there if spreading out the cost helps.

Ready to find your number? Call us at 603-610-1770 or book your free inspection. We will look at the whole basement, tell you what it actually needs, and get you a written quote within 24 hours.

See the full basement waterproofing page and the 603 guarantee for the details on coverage.

Related questions

Does waterproofing fix a cracked foundation wall? Not by itself. Waterproofing handles water. A structural crack may need crack injection, carbon fiber straps, or a brace. Crack injection runs $1,000 to $3,000. We tell you which one at the inspection. See structural and foundation repair.

Is exterior excavation waterproofing better? No, in our field experience. We have watched outside tar-and-dig fixes fail in about two or three years. Interior drainage stops the water where it shows up and lasts. That is the durable fix.

Does basement waterproofing come with a warranty? Yes. The Forever Dry System carries a transferable lifetime warranty, conditional on no other contractor touching the work. Pump system is 3 years and the dehumidifier is 5 years. See the 603 guarantee.

What if I want to finish the basement after? Get it dry first, then finish. We do basement finishing with our own crew, and that runs $30,000 to $200,000. A dry basement is the foundation a finished space sits on.