What is the best way to waterproof exterior walls when remodeling?

The best way to keep water out during a remodel is to manage it from inside the wall, with a full-perimeter interior drainage system, a wall vapor barrier, a sump pump, and a dehumidifier. Digging the outside back up to coat the walls feels like the obvious fix, but in our field experience that exterior dig fails in about 2 to 3 years and you pay for it twice.

Here is why the outside dig lets you down. When your house was built, the crew put loose fill back against the foundation. That disturbed backfill drains slowly and holds water. So water pools right at the wall. Add an NH winter and frost heave pushes those walls inward. Coating the outside does nothing about the water that already sits in that soil. The coating cracks, the dig settles, and the leak comes back.

Inside drainage works with the water instead of fighting it. We run drainage around the perimeter, catch the water at the floor wall joint, and send it to a sump pump that pushes it out. A vapor barrier on the wall keeps moisture off your new framing. A dehumidifier handles the damp air. That is our Forever Dry System, and it is for basements. It is 100% guaranteed to be dry for life! The lifetime warranty is transferable, with conditions.

If your remodel is over a crawl space, you want crawlspace encapsulation, not Forever Dry. That is a 12-mil wall vapor barrier, a 20-mil floor vapor barrier, dimpled drainage matting under the floor barrier, spray-foam-sealed seams, a dehumidifier, and a sump. The Department of Energy notes that up to about a third of a home’s heat loss can come from an uninsulated foundation or crawl space, so sealing it can help your comfort too. Encapsulation carries a 25-year warranty.

What drives the cost? Linear feet of wall, how deep the digging goes, your sump and pump setup, and whether you also need a foundation fix first. Basement waterproofing runs $3,000 to $30,000. Crawl space encapsulation runs $3,000 to $25,000. We give you the exact number after a free inspection, not before.

One thing most contractors skip telling you. You do not need exterior excavation waterproofing to stay dry. We do not even offer it, because we watched too many of them fail. Spend that money on a system that lasts instead.

A few remodel notes worth knowing. If you see cracks in the wall while it is open, that is the time to deal with them. Crack injection runs $1,000 to $3,000. Carbon-fiber straps for a bowing wall run $850 each. Both come with a 25-year wall stabilization warranty on the carbon fiber and a 10-year warranty on crack injection. If the wall is failing in a bigger way, like a full rebuild or wall anchors, we price that after we see it. We do repair, not new builds.

Worried about backup during a storm? Our backup sump is battery only. A charged battery pumps about a residential pool’s worth of water, roughly 15,000 to 20,000 gallons, before it runs down. That buys you time when the power is out.

We are 603 Basement Solutions, based in East Kingston NH, serving New Hampshire, Maine, and Massachusetts. We are trusted by 5,000+ homeowners in New England, rated 4.9 on Google across 250 reviews, and BBB A+ accredited. We self-perform our structural work in-house, so one crew owns the job.

Want to learn more before you commit? Read about basement waterproofing, crawl space services, and structural and foundation repair. Our 603 Guarantee lays out exactly what we stand behind. For radon during a remodel, see radon mitigation. The EPA sets the radon action level at 4.0 pCi/L and suggests considering a fix between 2 and 4.

Get your free inspection

Call us at 603-610-1770 or book your free inspection. We give you a quote within 24 hours, with no pressure. Let’s keep your remodel dry for good!

Related questions

Should I waterproof from the outside or the inside? Inside. Exterior digs fail in about 2 to 3 years in our field experience, because the disturbed backfill holds water and the coating cracks. Interior drainage with a sump and vapor barrier is the durable fix. See basement waterproofing.

Do I need to fix foundation cracks during a remodel? If they are exposed, yes, that is the easiest time. Crack injection runs $1,000 to $3,000 with a 10-year warranty. Bowing walls take carbon-fiber straps at $850 each. See foundation repair.

Can you waterproof a crawl space, not just a basement? Yes, with crawlspace encapsulation, which is different from the Forever Dry System. It uses a 12-mil wall and 20-mil floor vapor barrier, drainage matting, a dehumidifier, and a sump, and runs $3,000 to $25,000. See crawl space services.

Is the inspection really free? Yes. The inspection and the estimate are free, and we get you a quote within 24 hours. Financing is available through Hearth, subject to approval. Book your free inspection.