Searching "certified radon mitigation near me" or "Allouez radon mitigation" usually means one thing: a test already came back above the action level and now you want to know what actually happens next. Here's what installation day looks like, how long it takes, and how to make sure the numbers come down for good.
How long does a radon mitigation system take to install?
A standard sub-slab depressurization system in a single-family Wisconsin home typically takes one working day, roughly four to eight hours, from the first core hole to the final fan test. Most homeowners can expect the crew in and out before evening.
Larger homes, homes with more than one foundation type (a basement plus an attached crawlspace is common in older housing stock around Green Bay and Appleton), or homes needing more than one suction point because of interior footings can stretch the job into a second day. A sump pit that's already tied into the drain tile loop often speeds things up, since it can sometimes serve as the suction point instead of coring new holes.
What happens during a radon mitigation installation in Wisconsin?
The licensed operator drills a suction point through the concrete slab (or seals a crawlspace vapor barrier), runs PVC pipe from that point up through a closet or exterior wall, installs an inline fan in an unconditioned space like the attic or garage, and vents the pipe above the roofline and away from windows and doors, consistent with the venting guidance in ASTM E2121, the industry standard practice for installing radon mitigation systems in existing residences.
A few details worth knowing that generic listings skip:
- A U-tube manometer, a small glass gauge with colored liquid, gets mounted on the pipe so you can glance at it anytime and confirm the fan is still running.
- Other slab penetrations, cracks, and sump lids get sealed with polyurethane caulk or a gasketed cover, because an unsealed opening anywhere in the slab can rob suction from the main pipe.
- The fan needs its own dedicated electrical circuit in most installations, which is why an electrician is sometimes brought in alongside the mitigation crew.
Do I need a permit for radon mitigation installation in Wisconsin?
Permit requirements for radon mitigation systems vary by municipality across Wisconsin — some cities require an electrical permit for the new fan circuit while others don't require any permit for the work at all, so check with your local building inspector's office before work begins.
A licensed operator working regularly in your area, whether that's Brown County, Outagamie County, or Dane County, should already know the local building department's stance and can pull any required permit as part of the job rather than leaving it to you.
What certification should a radon mitigation contractor near Green Bay or Allouez-adjacent neighborhoods have?
Look for a contractor holding an active National Radon Proficiency Program (NRPP) or National Radon Safety Board (NRSB) mitigation credential, since Wisconsin relies on these national certification programs rather than issuing a separate state radon contractor license.
The Wisconsin Department of Health Services radon program maintains information on certified providers operating in the state. For a step-by-step guide to checking a specific installer's credentials before you sign anything, see how to verify a certified radon mitigation contractor in Wisconsin.
How soon after installation should the home be retested for radon?
EPA guidance calls for a follow-up radon test no sooner than 24 hours after the mitigation system starts running, with results in hand within about 30 days, to confirm the level has dropped below the EPA action level of 4 picocuries per liter (pCi/L).
Keep the system powered on the entire time the retest kit is placed — even briefly unplugging the fan to vacuum near it can skew a short-term test. If you're still deciding whether to test in the first place, what to expect from certified radon testing near you covers kit types and placement basics.
Does Wisconsin winter weather affect radon mitigation installation?
Yes — frozen or snow-covered ground can delay exterior trenching or crawlspace encapsulation work, and safely routing pipe and fans up an exterior wall or through the roof is harder with ice on the ladder access points, so many Wisconsin homeowners schedule mitigation installs for fall or spring.
That said, indoor sub-slab work happens year-round without much trouble since it's performed inside a conditioned basement. It's mainly the exterior-mounted pipe and fan variants, more common on homes without attic access, that installers tend to push toward milder weeks.
Radon levels themselves also shift seasonally — homes are sealed up tighter in winter, which is part of why counties across Wisconsin show elevated readings in colder months; see how Wisconsin counties compare on radon levels for the bigger picture. The licensed operators in our network handle installations across Brown County, Outagamie County, and other Wisconsin counties, including neighborhoods like Allouez-adjacent, Green Bay, Appleton, and West Appleton.
This article is for general information only and isn't legal, engineering, or medical advice. Permit rules, code requirements, and contractor licensing details vary by municipality — confirm current requirements with your local building department and choose a certified provider before scheduling any work.