Do You Have to Test for Radon When Selling a House in Wisconsin?

No. Wisconsin law doesn't require a radon test to sell a house, but if you already know your home has an unsafe radon level, you must tell the buyer. The Wisconsin Department of Health Services still recommends testing during a sale, and the EPA advises sellers to test before listing, so it usually pays to know your number before the house goes on the market.

What Wisconsin actually requires

The Wisconsin DHS page for home buyers and sellers says radon testing "is not required by law or regulated in Wisconsin." The same page sets out the one rule that does apply to sellers: you must inform the buyer of any known unsafe levels of radon. So the duty is about what you know, not about going out and measuring.

That has a practical side. If you tested in the past and got a high result, that's the kind of known level to talk over with your listing agent. Keep the report with your other house papers so it's easy to share.

Why testing before you list usually helps

The EPA's radon guide for home buyers and sellers recommends testing your home before you put it on the market and lowering the level if needed. The guide also notes that a buyer may ask for a new test, so finding out first gives you more control.

• You set the schedule. A high result found after you accept an offer lands in the middle of an inspection deadline. Found before listing, it's a project you can plan.
• You can show a clean record. The EPA suggests saving your test results and any details about work done to fix a problem, and notes this can be a positive selling point.
• Fewer surprises in negotiation. If the buyer's test comes back high, you're responding to their number. If you already fixed it, you hand over the paperwork instead.

If the buyer wants their own test

Plan for it. Even when you have a past result, Wisconsin DHS says the buyer decides whether earlier tests are acceptable, and DHS notes that short-term tests are usually the main test in a sale.

For a sale, DHS recommends a test of at least 48 hours under closed conditions, with windows and outside doors kept shut for 12 hours before the test starts. The test belongs in the basement or the lowest livable level of the home. DHS also recommends using a tester certified in a national radon measurement proficiency program for real estate transfers.

The EPA lists three short-term setups that work when a sale needs fast results: two passive tests side by side for at least 48 hours, two passive tests one right after the other in the same spot, or a continuous monitor for at least 48 hours. In each case, the home should be fixed if the average comes out at 4 pCi/L or higher. The EPA also warns that test interference can happen during a sale, which is one more reason buyers like a certified tester.

What the numbers mean for a seller

Wisconsin DHS recommends fixing radon at 4 pCi/L or greater, the same level the EPA uses. The EPA adds that levels below 4 still carry some risk and suggests considering a fix between 2 and 4 pCi/L. Our radon level checker explains where a result falls.

If your result is at or above 4, you have the usual choices: fix it before listing, fix it during the sale as part of the deal, or offer a credit so the buyer can handle it. How those negotiations tend to go is covered in our guide to radon in a home inspection, and typical price ranges are on our mitigation cost page.

Already have a radon system?

Say so in your listing materials. The EPA's Consumer's Guide to Radon Reduction asks sellers with a system to tell buyers about it and give them information on how it runs and how to maintain it. Pull together the installer's paperwork, any warranty, and your most recent test after the install. The EPA suggests retesting at least every two years, so if your last test is older than that, a new one before listing gives buyers a current number.

Selling soon and got a high result? Request a free quote and mention your listing or closing date in the message.

This guide sums up public information from Wisconsin DHS and the U.S. EPA. It isn't legal advice. Your listing agent or a real estate attorney can tell you how disclosure works for your sale.