I have a radon mitigation system that blows air out of my house. Is that normal?

Yes. That is exactly what an active radon mitigation system is built to do. The fan pulls radon gas out of the soil under your slab and pushes it up a pipe and out above your roofline, so the air blowing out is the system working. Radon mitigation with 603 starts at $900 to $6,000, and most homes land around $1,950 to $2,250.

Radon is a gas that comes up out of the ground. It seeps through the slab, through the floor wall joint, through tiny cracks you can’t see. An active sub-slab system drops a suction point through the slab, ties it to a sealed pipe, and runs a fan in line. The fan creates low pressure under the slab, so soil gas gets pulled into the pipe before it reaches your living space, then up and out above the roof. That stream of air you noticed is the radon leaving.

The fan should run all the time. Always on. If yours ever goes quiet, that is the thing to worry about.

Most active systems have a small gauge on the pipe called a manometer, a U-shaped tube with colored liquid. When the two sides sit at different heights, the fan is pulling suction and doing its job. When both sides level out, the fan has stopped. A tilt in the liquid is a good sign.

A few things trip people up. The exhaust carries radon, so the pipe should terminate above the roofline and away from windows, per EPA guidance ([verify] deep URL: epa.gov/radon). That keeps the gas from drifting back inside. If your vent ends at ground level or next to a window, that is worth a second look. The fan also moves a little house air out with the soil gas, so a system can have a small effect on heating in winter. That tradeoff is normal, and beats living with high radon.

The EPA action level is 4.0 pCi/L. At that number or above, you fix it. Between 2 and 4 pCi/L, the EPA says consider fixing ([verify] deep URL: epa.gov/radon). If you already have a system, someone decided your number was high enough to act on. NH DHHS publishes radon guidance for New Hampshire homes too ([verify] deep URL: dhhs.nh.gov).

Call someone in a few cases. The fan is silent. The manometer has gone flat. There is a loud new rattle or hum. Or you have a dirt or fieldstone crawl space and aren’t sure your setup is the right kind. For an open dirt floor, the answer is usually sub-membrane depressurization: we seal a heavy membrane over the soil and pull suction under it instead of under a slab. We install those. If your home has a finished slab and a crawl, you may handle each separately.

You probably don’t need a brand new system just because you can feel the exhaust. That part is normal. What you may want, if it has been a while, is to confirm it is still pulling and venting correctly. Our crew, led by Branden (we call him B-Radon), can tell you whether yours is sound or needs work.

A word on testing. We do the mitigation, but the retest after a system goes in is on the homeowner. You buy a test kit or hire a tester, run it, and read your own number. We won’t report a level we didn’t measure.

The foundation drives the cost most. A clean poured slab is one thing; a fieldstone or dirt crawl needs a membrane, more sealing, more labor. The pipe run, where the fan can sit, and whether multiple suction points are needed all move the number. Radon mitigation with us starts at $900 to $6,000, and most homes land around $1,950 to $2,250, and if you want a fresh test fee handled, that runs $50, credited toward the job if you move ahead. We give you a free inspection and a free estimate, and a quote inside 24 hours.

A lot of NH radon comes from the granite and soils under our feet up here. Radon-prone ground is common across New Hampshire, Maine, and Massachusetts, which is why we mitigate so many homes in the region.

Our radon mitigation work carries a 10-year warranty (we don’t guarantee a specific radon level unless it’s in writing). We are licensed and insured, OSHA-certified, with state radon certification RMS-113966, and trusted by 5,000+ homeowners in New England.

Want a set of eyes on your system? Call us at 603-610-1770 or book your free inspection and we will tell you exactly where yours stands.

Learn more about how we handle radon mitigation, and read the 603 guarantee. If you also fight water down there, our basement waterproofing and crawl space services pages cover that.

Related questions

Is it bad that my radon fan runs constantly? No. An active system is built to run nonstop. The fan keeps low pressure under your slab so soil gas never builds up. A fan that stops is the problem.

How do I know if my radon system is still working? Check the manometer on the pipe. If the liquid sits at two different heights, the fan is pulling suction and the system is working. If both sides are level, the fan has likely quit. Call us if you’re unsure.

Do I need to retest my radon after the system is installed? Yes, and that part is on you. You run a test kit or hire a tester and read your own number. We install and warranty the system. We don’t report a level we didn’t measure.

My crawl space is dirt. Can I still get radon mitigation? Yes. For a dirt or fieldstone crawl we install sub-membrane depressurization. We seal a heavy membrane over the soil and pull suction under it. Radon mitigation starts at $900 to $6,000, and most homes land around $1,950 to $2,250.