What is a radon test?

A radon test measures how much radon gas is in your home’s air, reported in picocuries per liter (pCi/L). The EPA says to take action if your level is 4.0 pCi/L or higher, and to consider fixing between 2 and 4 pCi/L. We can run a test for $50, credited toward the job if you move ahead.

Radon is a gas you can’t see or smell. It comes up out of the ground and seeps into a house through the basement or crawl space. A test is the only way to know if you have it. Two homes on the same street can read very differently, so your neighbor’s number tells you nothing about yours.

There are two main kinds of tests. A short-term test sits in the lowest lived-in level of your home for a few days, usually two to seven, then gets read. A long-term test stays put for more than 90 days and gives you a truer year-round average, because radon rises and falls with the seasons. Most folks start with a short-term test to get a quick read.

The number it gives you is a yearly average estimate in pCi/L. The EPA action level is 4.0. If you land at or above that, you fix it. If you land between 2 and 4, the EPA says to think about fixing it. There’s no level that’s truly zero. Even outside air has a little.

When you test matters too. Run it with the windows and doors shut as much as you reasonably can, and keep your normal heating going. Winter in New Hampshire is a strong time to test, because the house is sealed up tight and radon tends to read higher. A test run with the windows open all summer can read low and fool you.

You don’t always need us for this part. You can buy a test kit and do it yourself, or hire a measurement pro. We hold a state radon cert (RMS-113966), so we can test for you and read it right. But if money is tight, a hardware-store kit is a fine first step. We’d rather you know your number than skip it.

If your number comes back high, the fix is a radon mitigation system. For a normal poured or block foundation, that’s active sub-slab depressurization, a pipe and a fan that pull the gas out from under the slab and vent it above the roofline. For a dirt or fieldstone crawl space, we use sub-membrane depressurization instead, which pulls from under a sealed floor barrier. We install both. A mitigation system carries a 10-year warranty. We don’t guarantee a specific radon level unless it’s in writing.

What drives the test result is mostly your soil and your foundation, not anything you did. Radon comes from the ground, and some New England bedrock just gives off more of it. A cracked slab or an open floor wall joint gives the gas an easy path in. Backfill around a foundation is disturbed soil, looser than what was there before, and it lets gas and water move more freely toward the house.

A word before you spend. If you’ve never tested, test before you put money into a system. Plenty of homes read low and need nothing. There’s no sense buying a mitigation system you don’t need.

After a system goes in, retesting to confirm the level dropped is the homeowner’s job. That keeps it your number, on your timeline.

Radon ties into the rest of your basement, too. The same cracks and joints that let radon in often let water in. If you’re already looking at basement waterproofing or crawl space services, it’s a good time to test, since sealing and mitigation work hand in hand. See our radon mitigation page for how the system goes in, and the 603 guarantee for how we stand behind the work.

For the official guidance, read the EPA’s radon pages at epa.gov/radon and your state program at NH DHHS radon [verify]. Both explain testing and the 4.0 pCi/L action level in plain terms.

Want us to handle it? Call us at 603-610-1770 or book your free inspection and we’ll test, read the number, and tell you plainly whether you need a system or not.

Related questions

How long does a radon test take? A short-term test usually runs two to seven days in the lowest lived-in level of your home. A long-term test runs more than 90 days for a year-round average. Keep the house closed up during a short-term test for a true read.

What is a safe radon level? There’s no truly safe level, but the EPA action level is 4.0 pCi/L. At or above that, fix it. Between 2 and 4, the EPA says consider fixing it. Outdoor air carries a little radon too.

Can I test for radon myself? Yes. You can buy a test kit and run it yourself, or hire a measurement pro. We hold a state radon cert (RMS-113966) and can test for you for $50, credited toward the job if you move ahead, but a hardware-store kit is a fine first step if you just want your number.

Do you fix high radon? Yes. If your test comes back at or above 4.0 pCi/L, we install a radon mitigation system, active sub-slab for a normal foundation or sub-membrane for a dirt crawl space. It carries a 10-year warranty.