Is an invisible gas going to slow down your sale? In the Twin Cities, radon comes up in a lot of inspections, and it can surprise even well‑prepared sellers. If you’re planning to sell or buy in St. Louis Park, understanding radon helps you protect your health, your timeline, and your bottom line. In this guide, you’ll learn what radon is, how testing works in Minnesota, when to act, and how to keep negotiations smooth. Let’s dive in.
Radon basics in St. Louis Park
Radon is a colorless, odorless radioactive gas that forms naturally in soil and rock. It can enter your home through cracks, sump pits, floor drains, or any gaps where the foundation meets the ground.
The U.S. Environmental Protection Agency recommends taking action when long‑term average radon levels reach or exceed 4 picocuries per liter (pCi/L). You can read more about the EPA’s guidance on the EPA radon page.
Minnesota has higher radon potential than many other states, and elevated results are not unusual in Hennepin County. The Minnesota Department of Health explains regional risk and testing best practices on its Radon in Minnesota page.
Why testing is common here
Our colder climate means you keep windows closed for long stretches. Closed‑house conditions can allow radon to build up indoors. This is one reason you see radon testing in many St. Louis Park transactions.
Short‑term tests often happen during the heating season, which can produce higher, more representative readings for a quick snapshot. Long‑term tests, which run for more than 90 days, provide a better estimate of your home’s annual average.
Testing basics and timing
Short vs. long‑term tests
• Short‑term tests measure radon over 2 to 7 days, sometimes longer depending on the device. They are common in real‑estate timelines because they deliver fast results.
• Long‑term tests run for more than 90 days and better reflect your annual average by smoothing out daily and seasonal swings.
• MDH and EPA recommend long‑term testing for the most reliable picture, but short‑term tests are widely used in transactions due to time limits.
Where to place tests
Place the device on the lowest livable level that you use regularly. If your basement is finished and used, test there. Follow placement directions from your test kit or professional to avoid drafts, direct sunlight, or high‑humidity spots that can affect readings.
Closed‑house rules
For short‑term tests, keep windows and exterior doors closed for at least 12 hours before and throughout the test, except for normal entry and exit. Avoid running systems that bring in fresh outdoor air or strongly ventilate the area. The EPA outlines these closed‑house standards on its radon guidance page.
Who typically orders the test
• Pre‑listing test: You, the seller, test before going to market.
• Buyer‑ordered test: The buyer includes a radon test during the inspection period.
Both approaches are common in St. Louis Park. Pre‑listing testing can reduce friction and give buyers more confidence in your home.
Smart timing in a sale
Pre‑listing testing or mitigation
Pros
• You control timing and contractor selection.
• You can market low results or a documented system.
• Fewer last‑minute surprises during negotiations.
Cons
• Upfront cost.
• If levels are high, a buyer may still request verification after mitigation.
Testing during the inspection period
Pros
• The buyer verifies the current condition.
• You avoid upfront expenses if you are comfortable with negotiation risk.
Cons
• Elevated results can lead to repair requests, credits, or delays.
• You may need to schedule mitigation quickly to keep closing on track.
Mitigation that works
Most Minnesota homes use active soil depressurization, also called sub‑slab suction. A fan and pipe system draws soil gases from beneath the foundation and vents them safely above the roofline. Sealing major entry points helps, but the fan system does the heavy lifting.
Properly installed systems typically reduce levels below the EPA action level. Always verify performance with a post‑mitigation test and follow the installer’s guidance on maintenance. Learn how mitigation works and why post‑testing matters on the EPA radon site and MDH’s Radon in Minnesota page.
Installation can often be scheduled within days to a few weeks depending on contractor availability and your home’s layout. Costs vary by home type and complexity, but systems commonly range from several hundred to a few thousand dollars. Get local bids from MDH‑listed professionals.
How results affect negotiations
If your pre‑listing test is low or you have a documented mitigation system with a post‑mitigation test, you usually see fewer objections. Buyers appreciate clear records and a proven system.
If a buyer’s test shows elevated radon, common requests include seller‑paid mitigation, a repair credit, or a price adjustment. Buyers often ask for a post‑mitigation verification test and may also plan a long‑term test after closing. Clear contract language about test types, timelines, and closed‑house compliance helps everyone stay aligned.
What to document and share
Keep your paperwork organized so you can hand buyers a complete, confidence‑boosting packet:
• Original test report(s) with device type, device ID, test dates, location in home, and numeric result in pCi/L.
• If mitigated: installer invoice, system diagram or photos, installer qualifications, warranty info, and post‑mitigation test results.
• Operation details: where the fan is located, how to check the system indicator, expected noise level, and when to retest.
Upload documentation to the disclosure packet and listing materials. Note whether the test was short‑term or long‑term and confirm closed‑house compliance for short‑term tests.
Minnesota disclosure and guidance
In Minnesota, sellers typically complete standard disclosure forms and provide any known radon test results and mitigation records to prospective buyers. For state guidance on testing, mitigation, and lists of certified professionals, use MDH’s Radon in Minnesota resources. For national testing and action‑level guidance, review the EPA radon page.
For specifics on disclosure forms, contract language, or legal duties, consult your listing broker or a real‑estate attorney.
Seller checklist for St. Louis Park
Before you list
• Consider a pre‑listing radon test. Use closed‑house rules or opt for long‑term testing if time allows.
• If results are 4 pCi/L or above, consult an MDH‑listed mitigator and collect a post‑mitigation test result.
• Gather reports, invoices, installer credentials, warranties, and system instructions.
During the buyer’s inspection period
• Expect buyer‑ordered testing and agree on who pays for testing and any mitigation.
• If mitigation is requested, get bids from MDH‑listed professionals and document the plan.
At closing
• Provide full radon documentation to the buyer.
• Confirm in writing any post‑mitigation testing or follow‑up steps.
After the sale
• Encourage periodic retesting, especially after foundation or HVAC changes.
Local resources and next steps
• Testing and mitigation basics, action level, and closed‑house rules: EPA radon overview.
• Minnesota‑specific guidance, maps, certified labs and mitigators: MDH Radon in Minnesota.
Ready to plan your sale with fewer surprises? We can help you choose the right testing strategy, organize documentation, and present your home with confidence. Get your instant home valuation and connect with the team at Evergreen Realty Group to start a smooth, well‑planned listing.
FAQs
What is radon and why it matters in St. Louis Park
- Radon is a natural radioactive gas that can build up indoors; Minnesota’s higher radon potential makes testing a routine step for St. Louis Park homes.
What is the EPA radon action level in homes
- The EPA recommends taking action when long‑term average radon levels reach or exceed 4 pCi/L; learn more on the EPA radon page.
How do short‑term tests work during winter
- Short‑term tests run for a few days; follow closed‑house rules and place the device on the lowest livable level you use regularly for a representative result.
Does a mitigation system hurt resale value
- Typically no; a documented system with post‑mitigation results often reassures buyers and can reduce objections during negotiations.
What should Minnesota sellers disclose about radon
- Provide any known test results and mitigation documentation; for forms or legal details, consult your listing broker or a real‑estate attorney and use MDH’s guidance.
Where can I find certified radon professionals in Minnesota
- Use MDH’s statewide resources to locate certified testing labs and mitigation contractors on the Radon in Minnesota page.
