Radon Mitigation Cost in New Hampshire (2026)

If you want one number to anchor your budget: National Radon Defense, a national radon contractor network, puts a typical radon mitigation system at $800 to $2,500+ depending on home size and design (national figure, accessed June 2026). For a New Hampshire data point, one homeowner on r/newhampshire reported paying about $1,600 for an outdoor pipe-and-fan assembly from Advanced Radon Mitigation & Water Treatment (homeowner report, 2026). That is a single self-reported job, not a price list, so treat it as a real-world reference point rather than a quote you should expect.

This guide is independent. The figures below come from public sources, each labeled national or New Hampshire and dated. We do not take payment from any company to appear here, and the method we use to rank radon firms is published in full on our methodology page.

Why radon matters more in New Hampshire

New Hampshire sits on granite bedrock, and uranium in that granite breaks down into radon gas that seeps up through foundations. That geology is why radon is common across the state, and why New Hampshire health officials recommend testing every home. The EPA action level is 4.0 pCi/L (picocuries per liter): test above it and you should mitigate.

There is a second exposure path that surprises a lot of NH buyers: radon in well water. New Hampshire DHHS guidance considers radon-in-water reduction when levels fall between roughly 2,000 and 10,000 pCi/L. Radon in water is a separate system from radon in air, and it adds cost, which is the single biggest reason a New Hampshire quote can land well above the national air-only range.

The cost anchors

What drives the price

A radon air system is mostly a sealed pipe, a fan, and a vent path that pulls gas out from under the slab before it enters the house. The spread from $800 to $2,500+ comes down to a handful of things you can ask about before a quote:

Foundation type. A full poured-concrete basement on a single slab is the simplest case. Multiple slabs, an addition, or a finished basement with the slab buried under flooring all add labor and piping.

Sub-slab versus sub-membrane. A basement or slab home usually gets sub-slab depressurization: a suction point cut into the concrete, sealed, and vented. A crawl space instead needs a sealed membrane over the dirt floor with suction drawn from beneath it (sub-membrane depressurization). The membrane approach has more material and sealing labor, so a crawl space or mixed foundation tends to run higher than a clean basement slab.

The fan and the routing. Fan size scales with how tight the soil is and how much air the system has to move. Routing matters too: an interior run up through the house to the roofline is more involved than the outdoor pipe-and-fan assembly the NH homeowner above described at about $1,600 (homeowner report, 2026).

Radon in water. This is the big swing. If your well water tests high, NH DHHS guidance points to treatment (commonly aeration or granular activated carbon) somewhere between 2,000 and 10,000 pCi/L. That is a separate system with its own equipment, on top of the air mitigation. A national air-only range will not capture it, so if you are on a private well, test the water and price both.

Who does this work in New Hampshire

Radon mitigation in New Hampshire is led by dedicated radon specialists rather than the foundation companies. Advanced Radon Mitigation & Water Treatment in Hooksett carries the deepest verified review base of any radon firm we track (4.9 across 304 Google reviews, dated April 2026) and handles both radon-in-air and radon-in-water, which matters for the well-water case above; its full profile and verified record lays out the certification and scope. Airtight Radon Solutions in Nashua holds a perfect headline rating (5.0 across 98 Google reviews, June 2026), though its full review breakdown was not available when we last checked, so weigh that against deeper, fully verified records.

Two full-service firms also handle radon as part of broader basement work. 603 Basement Solutions in East Kingston runs radon mitigation in-house alongside waterproofing and foundation repair (4.9 across 250 Google reviews, June 2026), and radon mitigation is one of its most-mentioned review topics. Erickson Foundation Solutions in Hudson is a National Radon Defense contractor with radon mitigation showing up across 58 of its reviews (4.8 across 676 Google reviews, June 2026). If you are already opening up the basement for water or foundation work, folding radon into that scope with a single contractor can be worth pricing against a standalone specialist.

How to compare radon quotes

Get the suction-point count and the fan spec in writing, not just a lump-sum price. Two quotes that look far apart often differ because one assumes a single suction point and the other expects two, or because one routes the pipe outside and the other runs it through the house. Ask each firm what post-mitigation level they target (below 4.0 pCi/L is the floor; many systems get well under 2.0) and whether a post-install retest is included.

Pin down the retest specifically, because it is where quotes quietly diverge. A diagnostic visual inspection sets the suction point, but the only proof the system works is a follow-up radon test, usually a 48-hour or longer measurement run a few days after the fan is energized and the house has resealed. Some firms include that retest and a re-balance of the fan if the first reading is still high; others bill it separately or leave it to you to hire a tester. Get the retest, who runs it, and what happens if levels stay above 4.0 pCi/L written into the quote before you sign.

Certification is the other line to verify. New Hampshire does not run its own contractor radon license, so the credential to ask for is national: a mitigation provider certified through the NRPP (National Radon Proficiency Program) or the NRSB, which is what a firm like Advanced Radon Mitigation & Water Treatment carries. Ask for the certificate number and confirm it is current, not lapsed. Our published verified specialist rankings note which firms we have confirmed are certified and which we have not.

The sub-slab versus sub-membrane split shows up in labor, not just materials, so it is worth confirming which one your home needs. A poured-slab basement is straightforward sub-slab work: one or two cored suction points and sealing. A crawl space or a slab buried under finished flooring pushes the crew into sub-membrane work, laying and sealing a continuous barrier over the soil before they can draw suction, which is more hours on site and a real reason a crawl-space quote sits higher than a clean basement one. If a single quote spans both a slab and a crawl space, ask the firm to break the two out so you can see where the labor is going.

On a private well, ask for a separate water test and a separate water-treatment line item so the air and water costs do not blur together.

A standalone specialist is usually the lower-cost route for radon alone. A full-service firm makes more sense when radon is one item on a larger basement job, because you avoid coordinating two contractors. Neither is automatically cheaper; price both for your specific foundation.

Sources

• National Radon Defense, "Radon Mitigation System Cost" (national, $800 to $2,500+; accessed June 2026): nationalradondefense.com
• r/newhampshire homeowner report (about $1,600 for an outdoor pipe-and-fan job from Advanced Radon Mitigation; framed as a homeowner report, 2026): reddit.com/r/newhampshire
• New Hampshire DHHS, "Fixing Radon (Mitigation)" (radon-in-water reduction considered between 2,000 and 10,000 pCi/L; accessed June 2026): dhhs.nh.gov
• EPA action level of 4.0 pCi/L: stated by the U.S. Environmental Protection Agency.
• Company ratings, review counts, and scope: our verified records, dated in each company profile.

See our verified ranking: Best Radon Mitigation in the NH Seacoast.