Illinois Radon Awareness Act and Your Basement

What the Act says

The Illinois Radon Awareness Act, 420 ILCS 46, is a disclosure law. Sellers must give buyers the IEMA radon pamphlet and a disclosure form before the buyer is obligated, and landlords must disclose radon to tenants below the third story. Its statement of purpose is a recommendation:

“The Illinois Emergency Management Agency (IEMA) strongly recommends ALL homebuyers have an indoor radon test performed prior to purchase or taking occupancy, and mitigated if elevated levels are found.”

Illinois Radon Awareness Act (420 ILCS 46)

That is the gap homeowners miss. The Act makes radon a topic at sale and in leases. It does not make a homeowner test, mitigate or retest when they remodel. IEMA does recommend retesting after renovation, in its home measurement guidance (Illinois Radon Awareness Act, 420 ILCS 46, IEMA, guidelines for home radon measurement).

How a finished basement interacts with disclosure

Three points follow from the Act.

• You may have a test result to disclose. If you test before or after a finish, you hold information that bears on disclosure at sale. Keep the lab report with the permit file.
• A mitigation system raises a question, not a problem. A buyer will likely ask who installed it and what the post-installation test said. Licensed work with a dated test answers both.
• Renters in a basement unit. The Act covers tenants below the third story. A basement apartment is below the third story, so a landlord who finishes one has a disclosure duty on top of the permit and egress rules.

The state data point

IEMA says homes with elevated radon have been found throughout Illinois and that all homes should be tested regardless of geographic location (IEMA, radon in Illinois). That sentence is why a county-level zone label is not a reason to skip the test. Secondary sources list Winnebago County in EPA Zone 1, a predicted average indoor screening level above 4 pCi/L, but the EPA Illinois map PDF we retrieved did not render the county color, so check the map before using the zone (EPA, Illinois radon zone map).

What to do as an owner who is about to finish

• Test before you frame. See the testing guide.
• If the average is 4 pCi/L or more, price mitigation first. See the mitigation guide.
• Re-test in the finished room and keep both reports.
• If you rent the space, give the tenant the pamphlet and disclosure the Act requires.

Who to call

IEMA runs the radon program and licenses measurement professionals and mitigators. The Winnebago County Health Department sells radon test kits and says kits are also sold at local hardware and building stores (Winnebago County Health Department, radon). We found no Health Department rule that applies to finishing a basement.

What a seller does with a finished basement

When a house with a finished basement is sold, the seller's obligation under the Act is the same as for any house: give the buyer the IEMA pamphlet and the disclosure form before the buyer is obligated. The disclosure form asks what the seller knows. If you tested and mitigated, the lab report and the post-installation test are what you know. If you never tested, the form records that. Either way, a finished basement raises the number of questions a buyer asks, because the room is a place people sleep or work. Records from before and after the finish answer them.

A record to keep

• The date, location and result of each test, and who ran it.
• The mitigator's license number, the invoice and the system description if one was installed.
• The post-installation and post-remodel test results.
• The permit number for any radon plumbing permit your office issued.

Where to go next

This guide sits under Basement walls and moisture. Every price on this site, with its source and date, is on the basement finishing cost page. If this topic is on your list, these guides cover the neighbouring questions: Radon Test Before Finishing a Basement in Illinois, Radon Mitigation and Basement Finishing: Which First?, and Does a Finished Basement Count as Square Footage?.