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Buying or Selling? Test for Radon!

Are you buying or selling a home or do you work with people who are? Congratulations! Buying a new home is an important occasion and the perfect time to test for radon.

Radon is a naturally occurring, odorless, colorless, radioactive gas that is found in Wisconsin homes. Radon is the second leading cause of lung cancer in the United States, and the leading cause of lung cancer in non-smokers.

Real estate professionals may not be qualified to offer technical advice regarding radon and health risks.

We recommend that real estate professionals work with the Wisconsin Radon Program and our certified radon measurement and mitigation contractors for testing and fixing homes.

Test for radon before you buy

While radon testing is not required by law or regulated in Wisconsin, we recommend testing for radon during real estate transactions to better understand radon levels and lung cancer risk. Luckily, testing a home for radon is easy and can put both the buyer’s and seller’s mind at ease. If a radon test is conducted, it should be done in the basement or lowest livable level of the home.

Typically, the year average of radon levels in basements is double the radon levels on the main floors of homes where residents spend most of their time. Thus, long-term, year-long measurements provide a more accurate estimate of radon exposure and lung cancer risks. However, we recognize the time constraints of real estate transactions, and recommend that at least two-day, closed condition radon tests are conducted.

Certified testers

In Wisconsin, the seller must inform the buyer of any known unsafe levels of radon.

Certified individuals in a Radon Proficiency Program for Residential Measurement should be used for radon testing in real estate transfers. The U.S. Environmental Protection Agency (EPA) recommends mitigating (fixing) radon at levels of 4 pico Curies per Liter (pCi/L) or greater.

Fixing or mitigating a radon problem usually isn’t hard! While both home buyers and sellers in Wisconsin are free to negotiate and respond as they choose, it is ultimately up to the buyer to decide what is an acceptable level of radon risk in the home.

Tested home

If the home has previously been tested, the buyer must decide if the results of past tests are acceptable. In making this decision, the buyer should consider:

  • Level of radon found: If 4 pCi/L or greater, mitigation by a certified radon contractor is recommended.
  • Type of test: Short-term tests are usually the primary test performed in a real estate transaction. The minimum measurement duration is 48 hours with the house being under closed conditions 12 hours prior to the test (i.e., windows and doors remain closed).
  • Area of home tested: The lowest livable level of the home should be tested.
  • Who performed the test: Use of an individual certified in Radon Proficiency Program for Radon Measurement is recommended for real estate transfers. However, homeowners should have documentation if they performed the test previously.

Untested home

If the home has not been tested, the buyer should decide if they wish to request radon testing. If they buyer does wish to have radon testing, it should be brought up as soon as possible.

For radon testing prior to a home purchase or real estate transaction, the Wisconsin Radon Program recommends specifying:

  • Who will perform the test. Using a certified professional is recommended for a real estate transaction; however, the homeowner can also perform the test.
  • Type of test: a short-term (48-hour minimum) test is typical for real estate transaction.
  • Area to be tested: The lowest livable level of the home.
  • When the test will be done.
  • How the results will be shared between parties.
  • Who will pay for testing.
  • How the results will be used: The US EPA recommends mitigating (fixing) radon at levels of 4 pCi/L or greater.

To learn more, check out these resources:

  • Our Home Buyers Radon Brochure, p-01139 (PDF) provides recommendations for radon testing for buyers, sellers, and real estate professionals.
  • A short video for home inspectors and realtors describes how to deal with radon in real estate transactions.

Last revised September 28, 2022