What are the signs of radon under a house, other than a high test result?

There is no sign. You cannot see, smell, or taste radon, and there is no symptom in your house that tells you it is there. The only way to know radon is under your house is a radon test. A short-term test runs a few days. A long-term test runs more than 90 days. If the result comes back at or above 4.0 pCi/L, the EPA says to fix it. Between 2.0 and 4.0 pCi/L, the EPA says consider fixing it (epa.gov/radon).

We get this question a lot here in New Hampshire. People want a tell. A musty smell. A wet spot. A crack in the floor. None of that points to radon. Radon is a radioactive gas that comes up out of the ground, and it has no color and no odor. A house with a bone-dry, finished basement can have a high radon level. A damp old cellar can test low. The gas does not care how your basement looks or feels.

So what is the real indicator? Geology and the way your house sits on the ground. New England sits on a lot of granite, and granite-heavy soil tends to give off more radon. That does not mean your house has a problem. It means a test is worth doing. NH DHHS recommends every home in the state get tested, because levels vary house to house even on the same street.

How the gas gets in: it finds the openings. The floor wall joint where the slab meets the foundation wall. Cracks in the slab. Gaps around pipes. A sump pit that is open to the dirt below. An unfinished dirt or fieldstone crawl space, which is wide open to the soil. If you have any of those, you have a path for radon. Again, that is not proof you have high radon. It is a reason to test.

If a test comes back high, the fix is a radon mitigation system. For a normal poured slab we install an active sub-slab system: a pipe and a fan that pull the gas from under the slab and vent it up and out above the roofline, so it never enters your living space. For a dirt or fieldstone crawl space, we do sub-membrane depressurization, which is a sealed barrier over the dirt with the same vacuum pulling from underneath. Both run quiet and use very little power. Our crew lead on radon is Branden, and yes, the crew calls him B-Radon.

What drives the cost is the layout of your foundation. A simple single-slab basement is the low end. A house with multiple slabs, an addition, or a dirt crawl needs more piping and sometimes more than one fan, so it runs higher. The radon test itself is $50, credited toward the job if you move ahead and a mitigation system is $900 to $6,000, and most homes land around $1,950 to $2,250. We give you the number after a free inspection, in writing, with a quote within 24 hours.

Now the part where we talk you out of work you may not need. You do not need a mitigation system because a salesperson says so. You need it because a test came back high. If you have never tested, test first. A cheap short-term test kit or a state-listed tester will tell you where you stand. If you are under 2.0 pCi/L, you are fine and you do not need us for radon. We would rather tell you that than sell you a fan you do not need.

One more NH note. Radon and water often show up in the same basement, because the same cracks and the same open sump that let water in also let gas in. If you are already fixing a wet basement with our Forever Dry System or sealing a crawl space, that is a smart time to handle radon too, since the crew is already down there. But they are separate systems. Waterproofing does not lower radon, and a radon fan does not dry a basement.

If you want a clear read on your house, we will come look. Call us at 603-610-1770 or book your free inspection. We will test it, tell you the number, and only recommend a radon mitigation system if the test says you need one. Every job we do is backed by the 603 guarantee!

Related questions

Can I smell radon in my basement? No. Radon has no smell, no color, and no taste. A musty or damp basement is a moisture problem, not a radon sign. The only way to detect radon is a test (epa.gov/radon).

What radon level is dangerous? The EPA action level is 4.0 pCi/L. At or above that, fix it. Between 2.0 and 4.0, the EPA says consider fixing it. Below 2.0, no action is needed (epa.gov/radon).

Does a radon system come with a guarantee? Yes. Our radon mitigation carries a 10-year warranty on the system. We do not guarantee a specific radon level unless that is put in writing. After we install, the retest is yours to run.

Do I need radon mitigation if my basement is dry? Maybe. A dry basement can still have high radon, because the gas comes from the soil, not from moisture. Only a test tells you. If it is high, we fix it for $900 to $6,000, and most homes land around $1,950 to $2,250.