What steps would you take to waterproof your basement,

We waterproof a basement from the inside, and we do it in a set order. Find where water gets in, install full-perimeter interior drainage and a sump pump, line the walls with a vapor barrier, then add a dehumidifier. That is the Forever Dry System, and we guarantee it dry for life. A typical basement runs $3,000 to $30,000.

Here is the whole job, step by step.

We start by finding out where the water comes in. The first visit is a free inspection. Most leaks show up at the floor wall joint, the seam where the floor meets the wall. Water pools next to your foundation because the soil there is disturbed backfill, the loose dirt that got put back when the house was built. It drains slow and holds water. Then NH frost heave pushes on the walls all winter. So we look at the joint, the wall cracks, and where the floor stays damp.

Next we open the floor wall joint and run interior drainage. We cut a channel around the inside perimeter and lay a drainage pipe in it. Water that comes through the joint or down the wall drops into that pipe instead of onto your floor. The pipe runs by gravity to one low spot.

Then we set the sump pump. The pipe feeds a sump pit. We size the pump at 1/2 hp for every 120 feet of drain, so it keeps up. The pump throws the water out and away from the house.

We add a battery backup too. Storms knock out power, and that is exactly when you need the pump most. A charged backup battery moves about 15,000 to 20,000 gallons on its own, roughly a residential pool’s worth of water (pool volume per a standard pool-size reference [verify]). We do battery backup only. No water-powered units.

After that we line the walls with a vapor barrier. We hang a 12-mil vapor barrier on the walls. It catches any seep coming through the block and sends it down behind the wall into the drain. Your wall stays dry to the touch.

Last, we drop in a dehumidifier. Even a dry basement holds damp air, and damp air grows mold and musty smell. The dehumidifier pulls that moisture out so the whole space stays usable.

That is the full system. Now the part most folks ask about.

You do not need to dig up your yard. We do not do exterior excavation waterproofing. In our field experience it tends to fail in about two to three years once the dirt settles back, and you have paid for a big dig to get there. Interior drainage is the durable fix, and it does not tear up your landscaping.

You also may not need every piece. If your problem is only one wet crack and the rest of the basement is bone dry, you might just need crack injection, which runs $1,000 to $3,000. We will tell you that at the inspection instead of selling you the full system you do not need yet.

What drives the price is the size of the basement, how much perimeter we open, and whether the foundation needs any repair before we waterproof. If a wall is bowing, that gets handled first with carbon-fiber straps at $850 each or a power brace at $1,300 per brace. Those are foundation jobs, not waterproofing, and we keep them separate.

One more thing. The Forever Dry System is for basements. If you have a dirt or fieldstone crawl space, that is a different job called crawlspace encapsulation, which runs $3,000 to $25,000. Same goal, different build.

We have done this for 5,000+ homeowners across New Hampshire, Maine, and Massachusetts. The system is 100% guaranteed to be dry for life, and the warranty transfers if you sell. We are licensed and insured, BBB A+ accredited, and rated 4.9 across 250 Google reviews.

Want to know what your basement needs? Call us at 603-610-1770 or book your free inspection. We get you a quote within 24 hours.

Learn more on our basement waterproofing page, our structural and foundation repair page, and the 603 guarantee. For independent info on basement moisture, the U.S. Department of Energy’s Building America program covers foundation moisture control.

Related questions

Do I need exterior excavation to fix a wet basement? No. We fix wet basements from the inside with full-perimeter drainage. In our experience exterior digging tends to fail in two to three years, and interior drainage lasts. See basement waterproofing.

How much does it cost to waterproof a basement? A full Forever Dry System runs $3,000 to $30,000. The size of the basement and any foundation repair needed first are what move that number. We give a firm quote within 24 hours of the free inspection.

What if my crawl space is wet, not my basement? That is crawlspace encapsulation, not the Forever Dry System. It uses a 12-mil wall and 20-mil floor vapor barrier, drainage matting, sealed seams, a dehumidifier, and a sump. It runs $3,000 to $25,000. See crawl space services.

Is the sump pump protected during a power outage? Yes. We add a battery backup. A charged battery moves about 15,000 to 20,000 gallons on its own. We use battery backup only, not water-powered units.