Radon Mitigation in Minneapolis–St. Paul

Updated October 2026 · 6 public sources cited

Got a radon result of 4 pCi/L or higher in the Twin Cities? Here's how a Minnesota-licensed professional fixes it, step by step, and how to tell the job was done right.

Minnesota's rule: licensed installers only

Individuals doing radon mitigation in Minnesota must be licensed by the Minnesota Department of Health (MDH). The state's licensing framework comes from the Minnesota Radon Licensing Act.¹² MDH tells homeowners to avoid unlicensed installers and to ask for the installer's individual MDH license number, which you can check on MDH's radon professional lookup.¹

MDH also says the licensed individual should either be on-site doing the work or review the finished work at the end of the project.¹

Why Twin Cities homes so often need it

MDH says the average radon level in Minnesota is more than three times the U.S. level. It points to two causes: the state's geology, and the fact that Minnesota homes are closed up or heated most of the year, which can let radon build up.³ The "stack effect" makes it worse in winter. Warm air rises and escapes upstairs, and the replacement air is pulled in low, partly from the soil.³

Radon gets in through cracks in the slab, floor-wall joints, open sump pits and crawl spaces.³

The three system types MDH describes

Hennepin County notes that sealing cracks by itself "has not been shown to lower radon levels significantly or consistently." In most cases a fan-and-pipe system, called sub-slab depressurization, does the real work.⁵

Newer homes may already have a pipe

Hennepin County says every new Minnesota home since 2009 has been required to be built radon-resistant. That means sealed entry points and a vent pipe, but not a fan.⁵ If your newer home tests high, ask a licensed pro whether the existing passive pipe can be activated rather than building a system from scratch.

The 10-step process, per MDH

1. A test shows a problem.Your result is at or above the action level.
2. Request bidsfrom licensed radon mitigation professionals.
3. Walk-through.The professional visits to lay out the system.
4. Proposal.Review key questions and get it in writing.
5. Choose a professionalafter comparing bids.
6. Diagnostics.The pro may test to size the fan and place it correctly.
7. Sealing.Cracks and openings in the basement are sealed.
8. Installationof the system.
9. Walk-through of the finished system,with a full explanation of how it works.
10. Retestto confirm the level dropped.

Steps paraphrased from MDH.⁴

How to tell the install was done right

• The fan sits in an unconditioned space such as the attic, garage or outside, never in or below living space.⁴
• The exhaust pipe ends above the edge of the roof, at least 10 feet above the ground and 10 feet from windows, doors and openings, unless it vents at least 2 feet above them.⁴
• There's a U-tube manometer showing the fan is working, and an active notification monitor that alarms if it stops.⁴
• A system tag lists the installer's name, phone number, install date and license number.⁴
• You received written operating and maintenance instructions and copies of any warranties.⁴
• The electrical work was done by someone licensed. MDH notes most installs need an electrical permit.⁴

After the install

Run a post-mitigation test once the system has operated for at least 24 hours.⁴ MDH's goal is to get levels as low as reasonably achievable. Every system should get below 4 pCi/L, and a quality system may bring year-round levels below 2 pCi/L.⁴ If your system was installed after June 2020, MDH's Indoor Air Unit will inspect it for free.⁴

General information summarized from the public sources listed below. It isn't professional, medical or legal advice. A licensed professional who inspects your home can tell you what it needs.