Radon Mitigation in Amherst, NH

The Quick Version: Worried about radon? Amherst sits on New Hampshire granite, and granite is where radon comes from. Hillsborough County is EPA Radon Zone 2 (moderate, 2 to 4 pCi/L predicted), but homes here test high anyway. The county’s measured indoor average is about 5.3 pCi/L across 5,528 tested homes (American Lung Association / CDC tracking, 2008 to 2017), above the EPA 4 pCi/L action level. The fix is a certified radon system. It pulls the gas from under your slab and vents it up above the roof, and we have been doing this work in southern NH since 2015. Most jobs land between $1,950 and $2,250, with a full range of $900 to $6,000. Test first. Then call us. Free inspection, quote in 24 hours.

Branden runs our radon work. The crew calls him “B-Radon” because he has been beating this gas back since 2015. Got a basement or crawl space in Amherst? Give us ten minutes.

What is radon, and why does Amherst care?

Radon is a gas you can’t see or smell. It comes up out of the ground as the uranium in soil and bedrock breaks down. It sneaks into a home through cracks in the slab, gaps around pipes, sump pits, and dirt crawl-space floors. Then it pools in the lowest level you live in.

Now the Amherst part. New Hampshire is the Granite State for a reason, and granite is a classic radon source. The US Geological Survey and NH DHHS both tie the state’s high radon to that granite, and the southeastern and eastern parts of the state show the most homes with high levels (NH DHHS, Tracking Radon). Amherst sits right in that belt, in the Souhegan River valley between Milford and Merrimack. The valley floor through southern Amherst is mapped as alluvium and glacial sand and gravel over thin till on crystalline bedrock (Koteff, USGS Milford Quadrangle map GQ-881, 1970; NH DES GEO-195). That ground is loose and lets soil gas move easy, so radon shows up here no matter the zone.

Why radon is worth fixing

Radon is the second leading cause of lung cancer in the US, behind smoking. That’s the EPA’s finding, not ours, and it’s why NH tells every home to test no matter the zone. We are not here to scare you. The fix is simple and it lasts. Test first. If your number comes back at or above 4 pCi/L, mitigate. If it comes back low, you’re done.

Radon levels in Amherst, NH: the honest version

A lot of pages get the zone wrong, so let’s get it right. Hillsborough County, which includes Amherst, is EPA Radon Zone 2 (moderate), with a predicted average of 2 to 4 pCi/L (EPA Map of Radon Zones, New Hampshire). It is not Zone 1. In New Hampshire only Carroll County is Zone 1. Anyone calling Amherst a “high-risk Zone 1” town is reading the map wrong.

But the zone isn’t the whole story, and here’s the part that matters. Even in Zone 2, NH homes test high all the time. The measured indoor average for Hillsborough County is about 5.3 pCi/L across 5,528 tested homes (American Lung Association / CDC tracking, 2008 to 2017), above the EPA 4 pCi/L action level. The US average is near 1.3 pCi/L (EPA). So the rule in New Hampshire is simple. Test every home, zone or no zone. The only way to know your Amherst number is to test it. A $50 test settles it.

Testing for radon

Testing is cheap and quick. 603 charges $50 for a radon test, and that $50 comes right off the mitigation job if you move forward. A short-term test sits in your lowest lived-in level for a couple of days. A long-term test gives you a fuller read over time. Comes back at or above 4 pCi/L? Mitigation is the next step. Comes back low? Good news. You have your answer and you don’t need us yet.

A lot of Amherst homes run on private wells, and radon can show up in the well water too. NH DES says to treat well water for radon when the air level is over 4 pCi/L and the water tests high (NH DES, Radon in Your Home). We’ll tell you straight if that’s something to look into.

How radon mitigation works

The standard fix is sub-slab depressurization, an active radon system. We seal the obvious entry points, then run a vent pipe through the slab and add a quiet inline fan. That fan pulls radon out from under the foundation and pushes it up and out above the roofline, where it scatters off into the air. A little monitor on the pipe shows you the system is working. Most homes are done in a day.

Amherst has its share of older homes. The typical place was built around 1978 (US Census ACS 2024 5-year), but the town also holds 1700s and 1800s village and farmstead houses around the Amherst Village common, Cricket Corner, Ponemah, and Walnut Hill. Houses that old often have fieldstone or dirt-floor crawl spaces. For those, 603 installs sub-membrane depressurization: a sealed membrane over the crawl-space floor with the same suction system underneath. We handle both kinds.

This is a radon system. It is not our Forever Dry System, which is the basement waterproofing product. Different problem, different fix. Got water and radon both? We sort out the order on the inspection.

Cost of radon mitigation in Amherst

Here are 603’s real prices, the same ones we quote anybody in NH.

Service	Price
Radon mitigation system	$900 – $6,000 (most homes land $1,950 – $2,250)
Radon test	$50 (comes off the job if you proceed)

What moves the price is the house, not the town. A walk-out basement with an easy run for the vent pipe sits at the low end. A multi-zone home, a finished basement, or a fieldstone crawl space that needs a sealed membrane runs higher. We give you the number after we see it, and the quote lands within 24 hours. No surprises on install day.

Every radon system carries a 10-year warranty on the system and its parts. We don’t promise a specific radon level unless we put it in writing, because the gas is the ground’s, not ours. But we stand behind the system that keeps it down.

Amherst: local context

• County and zone: Amherst is in Hillsborough County, classified EPA Radon Zone 2 (moderate, 2 to 4 pCi/L predicted), not Zone 1 (EPA Map of Radon Zones, New Hampshire).
• Why test anyway: Hillsborough County’s measured indoor radon average is about 5.3 pCi/L across 5,528 tested homes (American Lung Association / CDC tracking, 2008 to 2017), above the EPA 4 pCi/L action level. Nationally the average is near 1.3 pCi/L (EPA).
• The geology: NH’s uranium-bearing granite is the source. The Souhegan River valley through southern Amherst is mapped as alluvium and glacial sand and gravel over thin till on crystalline bedrock (Koteff, USGS Milford Quadrangle map GQ-881, 1970; NH DES GEO-195), the kind of permeable ground that draws radon up through slab cracks, sump pits, and dirt crawl-space floors.
• Housing stock: The typical Amherst home dates to about 1978, and 91.9% of occupied homes are owner-occupied, with a median home value of $537,600 (US Census ACS 2024 5-year). Older village homes around Amherst Village, Cricket Corner, Ponemah, and Walnut Hill more often have fieldstone or dirt-floor crawl spaces that need a sub-membrane system rather than a simple slab fix.
• Climate: Amherst gets roughly 53 inches of snow a year (NCEI 1991 to 2020 normals at the nearest stations, Massabesic Lake and Nashua). Spring melt and a high water table are when basement-and-radon work pairs up most in this town.
• Action level: EPA recommends fixing a home at 4 pCi/L or higher (EPA Map of Radon Zones, New Hampshire).
• Permits and code: Radon work that ties into your home runs through the Town of Amherst Building & Code Enforcement office (Community Development), Town Hall, 2 Main Street, Amherst, NH 03031, (603) 673-6041 ext. 206; New Hampshire enforces the 2021 International Residential Code statewide (effective January 1, 2025) (Town of Amherst Building & Code Enforcement).
• Credentials: 603 is a state-certified radon mitigation contractor (cert RMS-113966), licensed and insured, with crews working southern NH since 2015.

What a recent customer said

603 Basement Solutions has a great team to work with. All involved are professional and courteous. The Radon Mitigation quote I received was the final price. I understand unseen problems occur, but I was fortunate. They estimated my radon levels would drop to around 2 but my monitor is reading a 7 day average of .4, WELL below what I was promised and even expected. Highly recommend 603 Basement Solutions

Jeff Eddy, ★★★★★ Google review

In Amherst, NH, 603 also handles basement waterproofing, basement finishing, crawl space encapsulation, foundation crack repair. Compare costs: helical piers, sill-beam replacement, lally columns.