Radon Mitigation System Installation in Willmar
A properly installed sub-slab depressurization system pulls radon out from under your foundation and vents it above the roof, where it disperses harmlessly. Most Willmar homes finish under 2.0 pCi/L, and most installs take one day.
How sub-slab depressurization works
Radon enters your house because the soil under the slab is at higher pressure than your basement. A mitigation system reverses that. We core a hole through the basement floor, dig out a small suction pit, and connect it to a PVC pipe run that exits above the roofline. An inline fan in the attic or outside the house keeps gentle, constant suction on the soil, so radon gets pulled out before it ever enters your home.
On most Willmar homes the job includes:
- One or more sealed suction points through the slab
- An airtight sump basket lid, since open sumps are a major radon entry point
- Caulked slab cracks and floor-to-wall joints where they matter
- A quiet inline fan sized to your foundation, not a one-size default
- A vent stack above the eave line, per code
- A manometer gauge so you can see at a glance the system is running
- The MDH system tag Minnesota has required on every install since 2019
Different foundations, different systems
Basements
The most common foundation in the Willmar area, and the most straightforward to mitigate. One suction point handles most homes; larger slabs or additions sometimes need two.
Crawl spaces
Handled with sub-membrane depressurization: a sealed vapor barrier over the dirt floor with suction underneath it. Common in older farmhouses around Kandiyohi County.
Slab on grade
No basement does not mean no radon. Slab homes get a suction point through the slab or a side-wall route. These jobs vary the most, which is why we quote after a few questions about the house.
Homes built after 2009: the cheap fix
Minnesota's building code has required passive radon-resistant construction in new homes since June 2009. If your house is newer, there is likely a capped PVC stack already running from under the slab to the attic. When a passive home still tests high, activating that stack with a fan is a smaller job than a full install, and it usually costs noticeably less. Test first, then activate only if the number says so.
After the install: proof, not promises
Every system gets a follow-up radon test after it has run for at least 24 hours. You see the before number and the after number. Minnesota licensing rules also require the installer's information and system details on the MDH tag attached to the unit, so any future owner, inspector, or agent can verify the work. If you are selling, that tag and the post-test result become part of your disclosure paperwork under Minnesota's Radon Awareness Act.