Get your basement dry for good
Derry sits up on high ground, and the water that soaks your basement starts here rather than backing up from a river.
Call 603-610-1770Get a free inspection
What it costs to waterproof a basement in Derry
A full basement waterproofing system from 603 runs $3,000 to $30,000. No games with the number.
The length of perimeter drain your basement needs is what moves it most, then the condition of the floor and whether you want a battery backup on the pump. One wet wall is a smaller job than a full perimeter with a sump and a dehumidifier.
Free inspection, free estimate, written quote within 24 hours. Financing runs through Hearth, subject to approval, and 603 makes nothing on it.
Why Derry basements get wet
Here is the thing about Derry that surprises people. There is no big river running through town to blame. Look at where the water gets measured. Beaver Brook drains Derry southward, and the USGS doesn’t gauge it until North Pelham (USGS station 010965852). The Spicket rises near Big Island Pond and isn’t gauged until North Salem (USGS station 01100505). Both sit well downstream of you.
That tells you something useful. Derry is where the water starts. Your wet basement isn’t a river coming up, it’s your own snowmelt and your own rain sitting in your own soil with nowhere fast to drain.
Which brings it back to the dirt against your wall. When the house was built, a crew dug the hole, set the foundation and pushed that same dirt back in. That backfill never packs down the way the undisturbed ground around it did. It stays loose, it drains slow, and it holds water right up against the foundation. On high ground with no river to carry it off, the water has to go somewhere, and the loose ring of soil around your house is the easiest path it can find.
Add the winter. The area averages around 53 inches of snow a year (NCEI 1991-2020 normals, via Current Results, nearest station Massabesic Lake). It melts all at once in March while the ground underneath is still frozen solid, so it can’t soak down. It travels sideways instead. Frost heave has been leaning on the walls all winter and working the floor wall joint open, and that joint is where you’ll see it come in.
How the Forever Dry System keeps it dry
Four parts, working together. A full perimeter drain along the inside edge of the floor at the floor wall joint. One 1/2 hp sump pump for every 120 feet of that drain so the pump keeps up instead of running hot. A vapor barrier on the walls. A dehumidifier, so the whole room is dry and not just the slab.
We back it. 100% dry for life or we come back free of charge, and it transfers to the next owner under our conditions. The sump pump system carries a 3-year warranty with batteries excluded, since batteries age on their own schedule no matter what we do.
Battery backup is worth it here. The storms that flood a basement are the same storms that drop the power, and a charged backup moves roughly a residential pool’s worth of water before it needs a charge. Ours is battery only. We don’t sell a water-powered unit.
What we won’t do is dig up the outside of your foundation. We’ve watched exterior digs fail in about two or three years. The backfill settles, the coating gives up, and you’re back where you started minus a lawn. Interior drainage lasts because you can get at it.
And if you’re dry, we’ll say so. A single crack in a wall that’s otherwise dry does not need a full system. Fill the crack and don’t look back.
Derry: local context
Derry grew fast. Most of the housing here went up through the seventies and eighties on what used to be farmland and woods, which means poured concrete and block foundations rather than the fieldstone we deal with in the older river villages. Those walls take interior drainage well. The catch with subdivision-era building is that lots were cut and graded to move dirt efficiently, and the backfill around those foundations is exactly the loose ring we just described.
Something else about Derry shapes the job. Seven in ten households here own their home, but only about half the housing is a detached single family house. So a lot of Derry owners are in townhouses and condos. If that’s you, the first call isn’t to us, it’s to your association, because the foundation and the basement are usually common area and the association owns that decision. We’re glad to walk the space with a board or a property manager and put the same written quote in front of them. (Housing age and ownership figures are in the sources below.)
This is the basement waterproofing page. If your problem is upstairs of the water, we also do foundation crack repair, crawl space encapsulation, basement finishing and radon mitigation around Derry. For what structural work actually costs, see lally columns and sill beam replacement.
If you’re near Beaver Lake or Island Pond
Derry has real standing water in it, and that changes the picture for the houses around it. A pond or a lake is the water table showing itself at the surface. If your house sits near one, the table under your basement floor is sitting high year round, not just during the March melt.
Those are the basements where a sump earns its keep every month instead of twice a spring. We size the pump to the drain the same way we always do, one 1/2 hp for every 120 feet. On a lakeside lot we look harder at the backup. A pump that runs constantly will eventually pick a bad night to quit.
Frequently asked questions
Why does my Derry basement get wet in the spring when there’s no river anywhere near me?
Because Derry is high ground, not low ground. You’re not getting river water, you’re getting your own snowmelt. About 53 inches of it comes down over the winter, melts in March into ground that’s still frozen underneath, and runs sideways into the loose backfill around your foundation. The brooks that drain the town don’t even get measured until they’re well south of you.
How much does basement waterproofing cost in Derry?
$3,000 to $30,000 for a full system, driven mostly by how much perimeter drain the basement needs. Free inspection, free estimate, written quote inside 24 hours.
I own a condo in Derry. Can I get my basement waterproofed?
Probably not on your own, and that’s worth knowing before you spend time on it. In most Derry associations the foundation and basement are common area, so the association decides and the association pays. Get us in front of your board or property manager and we’ll do the inspection and the written quote the same as we would for a single family house.
Do you dig up the outside of the foundation?
No. Everything we do is from the inside. Exterior excavation tends to fail in a couple of years once the dirt settles back, and it costs you the yard on the way through. Interior drainage is the one that holds up.
What a recent customer said
We had 2 inadequate sump pumps replaced by 603 Basement Solutions several months ago. This company was HIGHLY recommended by a trusted friend who had previously had disappointing results from other several companies. Chris and his team were great to work with: responsive and kept to their timetable. We also needed an electrician to complete this installation, and Chris coordinated that as well.
Jean Leen, 5 stars, Google review
Ready to get started?
Free inspection, free estimate, and a written quote in your hands within 24 hours.
Sources
Beaver Brook streamflow: USGS 010965852, Beaver Brook at North Pelham, NH. Spicket River: USGS 01100505, Spicket River at North Salem, NH. Snowfall: NCEI 1991-2020 normals, via Current Results (nearest station Massabesic Lake, 52.8 in/yr). Housing age and tenure: US Census ACS 2023 5-year, tables B25035 (median year structure built, 1982), B25003 (70% owner occupied) and B25024 (53% single unit). Pricing, warranty terms and the system build are ours, signed off by Chris and Nik.
