A large share of North Liberty homes were built under the North Liberty building code, which called for a radon vent pipe running from beneath the basement slab up through the roof. Iowa's seller disclosure statement never asks about that pipe. The radon question on the form asks whether the seller knows of any radon tests and, if so, when the last report was done and what it showed. Iowa HHS says there is currently no state rule requiring radon testing or mitigation during a real estate transaction.
Put those two facts together and a common North Liberty sale can close with a labeled radon pipe in the basement, a seller who honestly checks "no known tests," and a buyer who reads the pipe as a clean result. The pipe shows how the house was built. It says nothing about the air inside the house today.
Why so many North Liberty homes have the pipe
North Liberty adopted the International Residential Code's radon appendix in July 2005. Its current building code adopts the 2021 IRC with Appendix AF, "Radon Controlled Methods," under Ordinance 2023-20. According to Iowa HHS, before July 1, 2026, only 11 known jurisdictions in the state required radon-resistant construction in new single-family homes. The list included Johnson County, Iowa City, and North Liberty.
The town built a great deal of housing after that rule took effect. The Census Bureau's 2024 American Community Survey five-year estimates count about 8,739 housing units in North Liberty. Roughly 2,781 of them were built in 2010 or later, and another 2,818 were built between 2000 and 2009. These are survey estimates with margins of error, and the decade buckets can't separate homes built after mid-2005. Still, about a third of the town's housing dates from 2010 or later, all of it built under the radon rule.
Since July 1, 2026, Iowa's state building code requires a passive radon method from Appendix AF in all new one- and two-family homes. The rest of Iowa is now catching up to something North Liberty buyers have been seeing for about two decades. So the questions that sellers and buyers elsewhere are just starting to ask already come up in North Liberty sales.
What a passive system actually does
The EPA lists the parts of radon-resistant construction. There's a gas-permeable gravel layer under the slab, plastic sheeting over it, sealed openings in the foundation, a vent pipe running to the roof, and a junction box in the attic for adding a fan later. The EPA recommends labeling the pipe "Radon System."
A passive system has no fan. It counts on natural pressure differences and air movement to carry soil gas up the pipe. Wire in an inline fan and the system becomes active, pulling gas out and venting it outdoors. The EPA says radon-resistant techniques cut radon levels by 50% on average. An average drop isn't a promise for any one house, and that's why the EPA advises testing every new home after move-in, including homes with these features, and adding a fan if the result is 4.0 pCi/L or higher.
How well the system was installed matters too. Cody Smith of the Iowa Environmental Council told The Gazette that radon installers had come across homes where passive systems weren't installed correctly. He also noted that the new state law standardizes how these systems go in. Iowa's state medical director, Robert Kruse, said the same thing about home age in that story:
"The age of the home alone does not predict the radon level. Really, the only way to know is to really test."
A 2015 North Liberty house with a neatly labeled pipe and a 1970s house without one are in the same position on paper until someone tests them.
Where the pipe meets the disclosure form
The radon question appears on the Iowa Real Estate Commission's seller disclosure statement. The seller must provide the statement before making or accepting a written offer, and both seller and buyer acknowledge receiving the Iowa radon fact sheet from Iowa HHS. The form asks what the seller knows about tests. It doesn't require a test, and it doesn't ask about mitigation equipment as a separate question.
That leaves a gap in practice, and it cuts both ways:
- For a seller, an old result becomes part of the record. If you tested years ago and the result was high, it goes on the form with its date. If you never tested, the honest answer is no, and the buyer can still order a test during the inspection window.
- For a buyer, a "no known tests" answer in a house with a pipe simply means nobody has measured it. The EPA's home-sale guidance suggests running a new test even when a past result exists if it's older than about two years, if the house has changed since, or if you'll use a lower floor than the one that was tested.
The pipe still helps. Because the vent and attic junction box are already in place, the EPA says adding a fan is easier. In a North Liberty house built under the code, a high test result usually starts a conversation about activating an existing system. Without one, the conversation is about designing a system from scratch.
Why October is a practical time to test
Short-term radon results can change from day to day and season to season. For a two- or three-day test, the EPA says to keep windows and exterior doors closed as much as possible during the test and for at least 12 hours before it starts. Those closed-house conditions are much easier to keep in October than in June, when windows are open for showings. The EPA also recommends testing the lowest level a buyer could use regularly, so a finished basement office or family room is the spot to test.
Iowa doesn't require testing in any particular season, or at all during a sale. The 12-hour guideline comes from the EPA's consumer guidance, not from state real estate law. A seller planning a spring listing can still test this fall, when closed-house conditions are easy, and have a dated result to put on the form.
Who can do the work under the new rules
Under the Iowa Administrative Code, Iowa's radon rules changed on July 1, 2026, along with the building code. Anyone paid to test for radon now has to be an individually certified measurement specialist, which requires approved training, a national proficiency exam, and approved devices. The same Iowa Administrative Code also requires paid mitigation to be performed by an individually credentialed specialist. The rules generally call for testing before and after mitigation, with the follow-up test within 30 days, and the goal is to get the mitigated area below 4 pCi/L. Installing a passive system during new construction is exempt from the mitigation credential.
Certified testers report results to Iowa HHS, and Iowa Code generally keeps those results confidential unless the owner waives that. So a seller's past result reaches a buyer through the disclosure statement, not through a public database.
What the numbers look like
Testing is cheap. Johnson County Public Health sells short-term kits for $12 at its office or $15 by mail, and long-term kits for $30 in person or $33 by mail. It also recommends retesting after mitigation and testing every two years. James Lacina, an environmental health specialist with the county, told The Gazette that the kit price includes lab analysis and that he recommends using two short-term kits. The same story reported that Adios Radon in Tiffin offers free short-term tests. A 2025 Iowa Cancer Consortium article puts professional short-term testing at about $100 to $250.
Mitigation costs vary more. In its support for HF2297, the Iowa Environmental Council cited an EPA estimate that radon-resistant construction costs $350 to $500, compared with more than $3,000 for a system installed after the house is built. The Gazette reported installed-system costs of under $1,700 and about $2,300, and the paper noted that cost depends on the foundation. None of these sources gives a standard price for adding just a fan to an existing passive system, so get a quote from a credentialed mitigator for the specific house.
A short order of operations
For a seller in a North Liberty home with a passive pipe:
- Find the pipe and its label, and check whether there's a junction box in the attic.
- Test the lowest livable level under closed-house conditions, preferably before listing.
- If the result is 4.0 pCi/L or higher, get a quote from a credentialed mitigator to activate the system, and plan for the post-mitigation test.
- Put the date and result on the disclosure statement.
For a buyer:
- Read the radon line on the disclosure before you write an offer.
- If there's no recent result, schedule a test during the inspection period with a certified specialist.
- If the result is high, base the repair request on activating the existing system, using a written quote.
Quick answers
Does a radon pipe mean the house was tested? No. A pipe shows the house was built with radon-resistant features. Whether anyone has tested is a separate question, and the disclosure form only covers tests the seller knows about.
Is a radon test required to sell a home in Iowa? Iowa HHS says no state rule requires testing or mitigation during a sale.
Can I run the test myself? For your own information, yes, and county kits are inexpensive. If you pay someone to test for you, Iowa now requires that person to be a certified measurement specialist.
Do homes built after July 2026 still need testing? The EPA advises testing every new home after move-in, including homes with radon-resistant features.
If you're getting a North Liberty home ready for market or writing an offer on one, Jill Armstrong and the team can help you time a radon test around your listing or inspection dates and connect you with local professionals for the next step. Contact Us to set a plan before the disclosure form is due.
This article is general information, not legal, tax or financial advice. Consult a qualified professional about your situation.
