BedrockVetted

How to Vet a Basement or Foundation Contractor in NH

The cheapest way to lose money on a wet basement is to pick the contractor by the star average alone. For the same job, an interior drain and sump pump, a homeowner on r/newhampshire reported roughly $16,000 from one local company and about $40,000 from another in 2026 (thread). Both companies hold a 4.8 or higher rating. The rating did not tell that homeowner what the job should cost or which scope they actually needed.

This is an independent, sourced walkthrough of the checks that separate a good contractor from a costly one. It applies the same criteria we use to rank companies, the Bedrock Standard, to your own shortlist. Every cost below is labeled national or NH, dated, and linked to its source.

What this kind of work costs, in rough ranges

Use these as sanity checks, not quotes. A real number depends on your foundation, water table, and scope.

JobRangeScope / source
Basement waterproofing (national)~$3,000 to $7,000This Old House, Groundworks review, 2026
Basement waterproofing (national)~$8,000 to $16,000Modernize, which calls Groundworks at or above the industry average, 2026
Foundation repair (NH, Exeter)~$2,803 average, wide variationToday's Homeowner, Exeter NH page, 2026
Crawl space encapsulation (NH)~$4,030 to $8,990, ~$6,200 averagecrawlspacecosts.com, New Hampshire, 2026
Radon mitigation (national)~$800 to $2,500+National Radon Defense, 2026

The two national ranges do not agree, which is the point: "waterproofing" covers everything from sealing one bulkhead to a full perimeter drain, sump, and dehumidifier. Match the quote to the actual problem before you compare prices.

The six checks

Read the full review distribution, not the star average.

Open the company's Google reviews and look at the breakdown: how many five-star, and how many one-star. A 4.9 on 250 reviews is a different signal than a 4.9 on 12. 603 Basement Solutions shows 243 five-star against 2 one-star out of about 250, a 97.6 percent five-star share on a deep base (Google, June 2026). A perfect 5.0 on 10 reviews, like B-Dry System of New England, is an encouraging early signal but a thin track record. Read at least ten recent reviews and three of the lowest. You are looking for how the company handled the jobs that went wrong, because some of yours will.

Get the warranty in writing and confirm it transfers.

A verbal "lifetime guarantee" is not a warranty. Ask for the written document, read the term, and confirm in writing that it transfers to the next owner if you sell. 603 Basement Solutions publishes a transferable guarantee; Crack-X states a 10-year transferable warranty on most wall cracks; several local firms in our data, including Reliable Basement Waterproofing and NH Dry Basement, do not publish warranty terms on their websites, so you have to ask at the quote. Get the exclusions too. A drain warranty that voids if the sump pump fails is worth less than it sounds.

Ask who actually services the warranty later.

The install crew and the warranty-service crew are not always the same company. With a locally owned firm, the owner who quoted the job is usually who comes back. With a national consolidator like Groundworks (headquartered in Virginia Beach, VA, nearest branch in Hooksett, NH), warranty service runs through the national company. Ask directly: if the system fails in year six, who do I call, and is it a local owner or a national call center? For work where a callback at 2 a.m. in a March thaw matters, the answer changes the value of the warranty.

Check the BBB record for the legal entity that holds the warranty.

The warranty is only as good as the company behind it, so check that exact entity at the Better Business Bureau, not a similarly named one. Look at complaint volume and category, not just the letter grade. The corporate Groundworks profile shows 741 complaints closed in three years, about 69 percent of them service or repair (BBB national profile, accessed June 2026). A high service-or-repair share tells you how often customers had to escalate to get warranty work done. For comparison, Erickson Foundation Solutions shows 2 complaints in three years and Reliable Basement Waterproofing shows 0, on the profiles we checked in June 2026.

Confirm a named system and a scope that matches your actual problem.

A defined, named system tells you what you are buying and what the warranty covers. But a named system is not automatically the right system. The most common over-engineered upsell in this trade is a full perimeter drainage package sold for a problem that is actually a single cracked wall. If the issue is one leaking poured-concrete crack or a bulkhead, a crack-injection specialist like Crack-X is the focused, lower-cost call, and a full-basement system is overkill. If the issue is a settling or bowing wall, that is structural, and you want a firm that installs piers (helical piers, wall anchors), such as a Foundation Supportworks dealer or a foundation company that piers in-house, rather than a crack-only or surface contractor. Make the contractor name the problem before they name the system.

Get more than one itemized written quote.

One quote is a number. Two or three itemized quotes are a market. Insist that each quote break out the line items, the drain footage, the pump model, whether a new slab is included, the dehumidifier, so you can compare like for like. The TC Hafford homeowner report on Reddit, roughly $43,000, included an interior drain plus a new 4-inch slab, a wall membrane, two sumps, and a SaniDry dehumidifier (thread, 2026). That is a much bigger scope than the roughly $12,000 a different homeowner reported from Basement Improvements LLC for a drain, sump, and slab. Without itemized quotes you would be comparing two different jobs and calling it a price difference.

How to compare quotes that look different

When two quotes are far apart, the gap is almost always scope, not greed. Before you assume one company is overcharging, line up the line items and ask what the cheaper quote leaves out. Common omissions: no dehumidifier, no battery backup on the sump, no slab replacement, a shorter drain run, or a warranty that does not transfer.

The homeowner reports on r/newhampshire are a useful illustration precisely because they are not apples-to-apples. About $16,000 from 603 Basement Solutions for an interior drain and sump, and about $40,000 from Erickson Foundation Solutions for the same described scope, are homeowner-reported figures from a public 2026 thread, not company price lists. Treat them as a prompt to ask each contractor exactly what is and is not in their number, then judge the value, not the headline.

Match the company type to the job

The right company depends on which of four jobs you actually have.

If you are weighing a local independent against a national consolidator, our 603 vs Groundworks and Groundworks vs Erickson comparisons lay out the local-accountability trade-off with the verified numbers. The full set is at /compare.

Crawl space and radon need their own questions

Crawl space work splits into two products homeowners often conflate. Moisture encapsulation (a sealed vapor barrier, drainage, and a dehumidifier) is bought to keep the space dry; the average NH encapsulation project ran about $6,200 in 2026, typically $4,030 to $8,990 depending on size and scope (crawlspacecosts.com, New Hampshire). Insulation and weatherization (air sealing and insulation for energy) is a different job, priced and bought differently, handled by insulation specialists rather than waterproofers. Confirm which one the quote actually covers.

Radon is common in New Hampshire because of the state's granite bedrock, and New Hampshire health officials recommend testing every home. The EPA action level for radon in air is 4.0 pCi/L; for radon in water, New Hampshire DHHS guidance describes reduction as worth considering between 2,000 and 10,000 pCi/L (NH DHHS). A mitigation system runs roughly $800 to $2,500 or more nationally, depending on home size and design (National Radon Defense, 2026). One homeowner on r/newhampshire reported about $1,600 for an outdoor pipe-and-fan assembly from Advanced Radon Mitigation & Water Treatment (thread, 2026), a single homeowner's report rather than a price list. Ask whether the quote tests after install to confirm the level dropped below 4.0 pCi/L.

The short version

Read the review distribution at depth. Get the warranty in writing and confirm it transfers. Find out who services it later. Check the BBB record for the entity on the warranty. Make the contractor name the problem before the system. And get more than one itemized quote so you are comparing the same job. Do those six things and the price gaps usually explain themselves.

Sources

See our verified rankings: Best basement waterproofing on the NH Seacoast, or browse all of our guides and comparisons.