Radon mitigation & testing in Hollis, NH

Older farmhouses, granite bedrock and drilled wells in Hollis

If you live in an older Hollis farmhouse or a rural home on its own well, radon is worth a closer look. NH DHHS says radon exposure in New Hampshire is greater than the national average because of our granite bedrock. (NH DHHS)

Start with an air test

The EPA says to place a test in the lowest lived-in level: the basement if it is used often, otherwise the first floor. (EPA) NH residents can order a free state test kit. (NHDES) Breathing radon in indoor air is a much bigger risk than radon in water, so NHDES says to always test the air. (NHDES)

Old foundations: fieldstone, dirt floors and crawl spaces

The EPA notes it is common for a home to have a basement under one part and a slab or crawl space under the rest, as with many added-on farmhouses. In that case, a combination of radon reduction techniques may be needed. (EPA) For an earth-floor crawl space, the EPA calls covering the floor with a high-density plastic sheet and venting beneath it with a pipe and fan (submembrane suction) the most effective method. (EPA) Sealing cracks helps other methods work, but the EPA does not recommend sealing alone. (EPA)

Worried about a granite-block foundation or granite hearth? NHDES says radon from stone building materials is usually insignificant. Most radon comes up from the bedrock and soil through cracks and openings. (NHDES)

Drilled well or dug well?

NHDES says radon is common in water from bedrock (drilled) wells, while dug wells and point wells tend to have little or none. (NHDES) If your Hollis home has a drilled well:

• Test the water for radon at least twice, about a month apart, before deciding on treatment. (NHDES)
• Also test for uranium and gross alpha, which NHDES recommends for private bedrock wells. (NHDES)
• NHDES recommends treatment at 10,000 pCi/L or more, and says it may be advisable between 2,000 and 10,000 pCi/L if indoor air is above 4 pCi/L. (NHDES)

Full details on testing and treatment: our guide to radon in well water in NH.

Choosing who does the work

NH requires radon-in-air mitigation designers and installers to be nationally certified. (NHDES) You can check names in the NRPP directory. Ask for a home visit before the quote, and retest after the system is installed. (EPA)

Nearby

See Amherst, Milford and Nashua.

Well pump or pressure trouble? Our sister referral site, NH Well Pump Help, connects Hollis homeowners with local well pump pros.