I want to waterproof my basement, but first I have to stop water coming from the floors and walls. How do I stop the water from floors and walls?

You don’t stop the water at the floors and walls. You manage it. The lasting fix is an interior drainage system that catches water where the floor meets the wall, routes it to a sump pump, and pumps it out. Patching cracks or sealing the walls alone won’t hold, because the water keeps coming and the pressure keeps building. A full interior waterproofing system runs $3,000 to $30,000, and ours is guaranteed dry for life.

Here is why water shows up in the first place. When your house was built, the crew dug a hole, set the foundation, then put the dirt back. That dirt is disturbed backfill. It’s looser than the packed ground around it, so it drains slow and holds water against your walls. Add an NH spring thaw or a heavy rain and that soil turns into a wet sponge pressed up against your foundation. The water finds the weak spots. It seeps through the floor wall joint, through hairline cracks, through the pores in the concrete itself.

People want to stop it from the outside. Dig down, tar the wall, backfill, done. We don’t do exterior excavation waterproofing, and we’ll tell you why. In our field experience that fix tends to fail in a couple of years. The coating cracks, the soil shifts, and you’re wet again with a torn-up yard. The durable answer is interior drainage. You let the water in on your terms and send it straight to the pump.

How the interior system works

We call ours the Forever Dry System. It is basement only.

A crew cuts a channel around the inside perimeter of your basement floor, right at the floor wall joint where most of your water comes through. We lay in a full-perimeter drain that catches seepage from the floor and the base of the walls. That drain feeds a sump pump, sized at 1/2 hp for every 120 feet of drain line, which pumps the water up and out away from the house.

Then we handle the walls. A 12-mil vapor barrier goes over the foundation walls so any moisture pushing through the block runs down behind it and into the drain instead of into your basement air. Last, a dehumidifier pulls the damp out so the space stays dry and stops smelling like a basement.

That’s the system. Catch it, drain it, pump it, dry it. The Forever Dry System is 100% guaranteed to be dry for life, and the warranty transfers if you sell the house (conditional, so don’t let another contractor touch the work or it voids).

What you might not need yet

If your walls are cracking, bowing, or pushing inward, that’s a different problem. NH frost heave can shove a wall in over time, and that’s structural, not a water job. You’d be looking at crack injection, carbon-fiber straps, or piers. But you don’t need any of that just to stop seepage. Don’t let anyone sell you foundation work when all you’ve got is water. See our structural and foundation repair page if you suspect movement, otherwise stick with basement waterproofing.

Got a crawl space instead of a full basement? That’s a different fix too. We encapsulate those, see crawl space services.

A note on the pump

The pump is the heart of the whole thing, so it needs a backup. We add a battery backup pump for when the power goes out, which around here usually happens in the same storm that floods your basement. A charged backup battery keeps the pump running through an outage before it needs a recharge. Plenty to get you through an outage.

What drives the cost

A full interior system runs $3,000 to $30,000. The number moves with how many feet of drain your perimeter needs, how many sump pits, and whether you want the full wall barrier and dehumidifier or just the drainage. Bigger basement, more drain, more pump. We give you a free inspection and a free estimate, and you get the quote within 24 hours. Financing is available through Hearth (subject to approval), and we make nothing on it.

We’re 603 Basement Solutions out of East Kingston, NH. We’ve kept basements dry for 5,000+ homeowners across New Hampshire, Maine, and Massachusetts, we’re rated 4.9 on Google across 257 reviews, and we’re BBB A+ accredited. Angel runs our waterproofing crews. We do the work ourselves, so the 603 guarantee is ours to stand behind.

Stop fighting the water. Call us at 603-610-1770 or book your free inspection and we’ll come look at exactly where it’s getting in.

Related questions

Will sealing or waterproofing paint stop the water? No, not for active seepage. Sealers and paints can slow surface dampness, but they don’t relieve the water pressure pushing in from the backfill. The water just finds another way through or pops the coating off. Interior drainage is the lasting fix.

Do I have to dig up my yard to fix a wet basement? No. The durable fix is interior, not exterior. We cut a drain channel inside along the floor wall joint and route water to a sump pump, so your landscaping stays put.

My walls are bowing, is that a water problem? That’s structural, usually from NH frost heave and soil pressure. Water and a leaning wall are two different jobs. You can drain the water with waterproofing and stabilize the wall with carbon-fiber straps or piers. See foundation repair.

How long does an interior system take to install? Most basements are a few days of work, depending on the size of your perimeter and how much wall barrier and dehumidifier you add. We give you the timeline in your free estimate.