How to make sure your basement stays dry

The reliable way to keep a basement dry is to move water away on the inside with a full-perimeter interior drain feeding a sump pump, then block humidity with a wall vapor barrier and a dehumidifier. That is the Forever Dry System. It runs around $3,000 to $30,000 for a typical basement, and it is 100% guaranteed to be dry for life!

Here is why that works. Most wet basements are not a plumbing problem. They come from water pressure against the walls.

When your house was built, the crew dug a hole, set the foundation, then pushed the dirt back. That dirt is disturbed backfill. It is looser than the packed ground around it, so it drains slowly and holds water against your walls. Add a New England winter and frost heave starts pushing those walls inward. Water finds the floor wall joint, the spot where the wall meets the slab, and it seeps in.

So drying a basement is about managing that water, not hoping it goes away.

What actually keeps it dry

Interior drainage first. We cut a channel around the inside perimeter, lay a drain, and route everything to a sump pump. The pump moves the water out. We size it at 1/2 hp for every 120 feet of drain, so it keeps up. Add a battery backup so the pump still runs when the power drops in a storm. A charged backup battery can pump about a residential pool’s worth of water, roughly 15,000 to 20,000 gallons, before it needs power again.

Then the air. A wet floor is half the fight. The other half is humidity coming through the walls. We hang a 12-mil wall vapor barrier to stop that, and we set a dehumidifier to pull the rest out of the air. Now the space stays dry and it does not smell like a basement.

That whole package is the Forever Dry System, and it covers basements only. It carries a full transferable lifetime warranty. The sump pump system is warrantied 3 years, batteries excluded, and the dehumidifier 5 years.

What you might not need

Plenty of folks call us asking about digging up the outside of the house. We do not do exterior excavation waterproofing, and we will tell you why. In our experience that fix tends to fail in about two or three years, then you are back to square one with a torn-up yard. Handling the water on the inside lasts. So if someone quoted you a big dig, get a second look before you commit.

You also may not need foundation work to stay dry. Cracks, bowing walls, and sinking floors are structural, and those are separate jobs like crack injection, carbon-fiber straps, or helical piers. If your only problem is water, you may not need any of that yet. We will say so when we see it.

What drives the cost

A basement waterproofing job runs around $3,000 to $30,000, and the number moves with the size of your perimeter, how many pumps you need, and whether the floor wall joint is the only entry point or water is coming through the walls too. If you have a crawl space instead of a full basement, that is a different fix called crawlspace encapsulation, usually around $3,000 to $25,000. An uninsulated crawl or foundation can account for up to about a third of a home’s heat loss, per the U.S. Department of Energy, so sealing it does double duty.

We do a free inspection and a free estimate, and you get a written quote within 24 hours. Financing runs through Hearth, subject to approval, and we make nothing on it.

Want the full rundown of what is covered? Read the 603 Guarantee and our basement waterproofing page.

A little NH framing

New Hampshire ground freezes hard, thaws, and freezes again. That cycle is rough on foundations, and it is why so many basements that were fine for years suddenly start leaking. You are not doing anything wrong. The ground is just working against the house. The good news is the fix is permanent once it is in.

Trusted by 5,000+ homeowners in New England, rated 4.9 on Google across 250 reviews, BBB A+ accredited, licensed and insured. We self-perform the work with our own crew.

Call us at 603-610-1770 or book your free inspection. We will look at your basement, find the water, and tell you exactly what it takes to keep it dry for good.

Related questions

Will a sump pump alone keep my basement dry? A pump is the engine, but it needs the drain to feed it and the vapor barrier and dehumidifier to handle humidity. On its own a pump only moves the water that reaches it. The full Forever Dry System is what carries the dry-for-life guarantee.

What happens to my sump pump in a power outage? That is what the battery backup is for. A charged backup battery pumps roughly 15,000 to 20,000 gallons, about a pool’s worth, so the basement stays dry through a storm until power returns.

Do I need to fix my foundation to stop water? Not always. Water entry and structural damage are two different problems. If your walls are sound and water is just seeping in, interior drainage handles it. If you have cracks or bowing, see structural and foundation repair. We will tell you which one you actually have.

Is exterior waterproofing better than interior? In our field experience, exterior digs tend to fail in two or three years and tear up the yard doing it. Interior drainage is the durable fix, which is why it is all we install.