Radon and Iowa Real Estate: What Buyers and Sellers Need to Know Before Closing

Iowa has one of the highest radon rates in the country. The Iowa Radon Survey found that 71.6% of Iowa homes exceed the EPA's action level of 4.0 pCi/L, and all 99 Iowa counties are designated EPA Zone 1. Sellers must disclose known radon results under Iowa law, buyers can request a 48-hour test during the inspection period, and mitigation typically costs $900 to $1,800 and takes one day.

The first time most buyers and sellers hear the word "radon" is in the middle of a transaction. The inspector has finished, the report lands in your inbox, and somewhere in there is a number you weren't expecting, and now you're trying to figure out what it means, whether it kills the deal, and who pays for what.

It doesn't have to catch you that way.

Iowa is one of the highest-radon states in the country, and that is geology, not opinion. The glacial soils blanketing most of central Iowa are naturally uranium-rich, and uranium breaks down over time into radon gas, which seeps through the soil and enters homes through foundation cracks, sump pits, floor drains, and gaps around utility penetrations. The EPA designates all 99 Iowa counties as Zone 1, meaning every county in the state has a predicted average indoor radon level above the EPA's 4.0 pCi/L action threshold. The Iowa Radon Survey measured it directly and found 71.6% of Iowa homes test above that level. Whether you are in Ankeny, West Des Moines, Bondurant, or anywhere else in Polk or Dallas County, you are in Zone 1.

The law, the process, and the fix are all more manageable than most people expect once someone explains them clearly.

What makes Iowa's radon levels so high?

Iowa's glacial geology is the reason. When glaciers retreated across the state thousands of years ago, they deposited soils high in uranium and radium, and as those minerals decay underground, they produce radon gas. The gas has nowhere to go but up, so it moves through porous soil and enters buildings through any available gap. There is no neighborhood in the Des Moines metro that sits on meaningfully different geology than the rest.

Radon can be found in homes of any age and any construction type, with or without a basement. Finished basements do not block it. Age does not protect against it. The Iowa Department of Public Health puts the statewide prevalence at 50 to 70% of homes above the action level, and the measured survey data puts that figure at 71.6%.

Polk County is among the Iowa jurisdictions that required radon-resistant construction in new builds before the July 2026 statewide rule. Communities including Altoona and Bondurant have had local radon-resistant construction requirements on the books for years. And starting July 1, 2026, Iowa's building code requires all new single- and two-family homes to include passive radon mitigation as part of construction, a change that reflects how seriously the state has come to treat this. Buyers comparing new construction to resale in Ankeny and Waukee should understand what that requirement does and does not guarantee — passive systems reduce the risk, but buyers in new builds should still test.

What does Iowa law require sellers to disclose about radon?

Iowa law requires sellers to disclose any radon knowledge they have as a material fact. Under Iowa Code §§ 543B.9 and 543B.18, sellers and their agents must disclose conditions material to the transaction, and radon, if known, qualifies. The Iowa Seller Disclosure form includes radon as a specific category under Iowa's property condition disclosure law (Iowa Code § 558A). If you have had the home tested, those results go on the form. If you have a mitigation system in place, that must be disclosed too.

Sellers must also provide buyers with a copy of the Iowa Radon Home Buyers and Sellers Fact Sheet, published by the Iowa Department of Public Health, and document that the buyer received it. That receipt matters. A missing receipt is a disclosure gap regardless of whether the form was otherwise complete.

What the law does not require is testing before listing or remediation before selling. The IDPH recommends testing all Iowa homes before a sale, but that recommendation is not a legal obligation. If you have never tested and have no radon knowledge at all, you disclose that fact and move on.

One detail worth flagging for sellers who have sold before: if you think you "disclosed everything" in a prior transaction, confirm that radon was listed on the actual Iowa Seller Disclosure form, not just mentioned in conversation. The form has specific categories. General disclosure does not substitute for the specific box.

A note on a practice you may see in MLS agent remarks: some sellers instruct their agents to note that the seller has no knowledge of radon, the buyer may test for their own information, and the seller will not participate in mitigation or be informed of the results. This is not how Iowa's disclosure law is meant to work. Buyers have the right to request any inspection they choose, and sellers and their agents have a legal obligation to disclose material defects. Choosing not to know about a defect does not relieve that obligation. If a material condition exists and you elect not to address it, that posture creates more legal exposure than the radon reading itself ever would.

Can buyers request radon testing in Iowa?

Yes, and it is common practice in the Des Moines metro. Buyers include radon testing as part of their inspection contingency, and most experienced buyers do. The test runs 48 hours, conducted by a licensed measurement professional using a continuous radon monitor. Results come back as a formal report, not just a number, which matters when you need to negotiate or want documentation for a mitigation contractor.

Timing inside the inspection period is important. Whatever window you negotiated, request radon testing within the first day or two, not the last. A test started on day eight leaves almost no room to respond to a high reading, negotiate a resolution, or get a mitigation quote before your contingency expires. Plan accordingly, and confirm with your agent when the window opens and closes.

The Iowa Department of Public Health maintains a list of licensed radon testers across the state. Iowa certifies these professionals, and results from unlicensed testers may not hold up in a negotiation or with a lender.

A high radon reading is not a reason to walk away from a house. It is a reason to negotiate with the numbers in front of you.

What happens when the radon test comes back high?

A reading above 4.0 pCi/L during the inspection period gives both sides options, and none of those options automatically ends the deal.

The seller can install a mitigation system before closing, which is common when the reading is high and the seller wants to demonstrate the issue is resolved. The seller can also offer a credit so the buyer handles installation after moving in. Parties sometimes renegotiate price to account for the cost of mitigation, though this is less common when the fix is a known, bounded expense. And buyers can choose to take the home as-is, accepting the reading and arranging mitigation on their own timeline.

Which path makes sense depends on where the deal stands and how motivated both sides are. Any reading above 4.0 pCi/L crosses the EPA action level, and the path forward is the same regardless of how far above it the number lands. The options do not change whether the reading is 4.3 or 43. The number affects the urgency of the conversation. It does not change what the fix is. Understand how earnest money works inside your contingency window before you decide how to respond, because the clock on your deposit starts the moment the inspection period opens.

A home with a mitigation system already installed is not a lesser home. The system is the solution, not a flag. Buyers sometimes treat existing mitigation as a warning sign. It is the opposite. It means the problem was identified, addressed, and tested post-installation. That documentation has value.

One of our buyers, Amy, purchased a home in Ankeny where the reading came back at 43 pCi/L, the highest I had seen. We asked the seller to mitigate. They did, and the deal closed on schedule. A high reading is not a deal-killer. It is a line item.

How much does radon mitigation cost in the Des Moines area?

For most homes in the Des Moines metro, mitigation runs $900 to $1,800 and takes a single day. Cost varies by foundation type:

West Des Moines homeowners should know about the West Des Moines Radon Mitigation Program before spending anything out of pocket. The city offers grants up to $5,000 per home for eligible owner-occupied and rental properties within city limits. The grants cover both testing and remediation costs and do not need to be repaid. Income eligibility applies at 80% of Area Median Income, with thresholds ranging from $64,150 for a single-person household to $113,600 for a household of seven. Contact the city's Housing Department at (515) 273-0770 or housing@wdm.iowa.gov for application details.

For Des Moines metro clients, we recommend calling Central Iowa Radon. Corey and his team are easy to work with, consistently come in at a reasonable price, and their fans carry a 10-year warranty. If you need a licensed contractor for a mitigation installation, start there.

Use a licensed contractor for any mitigation work. The Iowa Department of Public Health certifies radon professionals, and an unlicensed installation can create problems at your next sale.

Should sellers test before listing?

Yes. The reason is practical: a radon issue found by a buyer's inspector midway through the inspection period forces you into a negotiation under pressure, on the buyer's timeline, with their contingency clock running. A radon issue you found before you listed gives you time to remediate, document the post-mitigation reading, and put a clean result in the buyer's hands.

Pre-listing testing typically runs $150 to $300. That is a small number relative to the leverage it gives you and the conversation it can prevent.

When we walk through an estimate of proceeds with sellers before listing, we talk through expenses that can come up during a home inspection, and radon mitigation is one of them. Not because every house will test high, but because if it does, we want you to have already accounted for it. A seller who has already budgeted a potential $1,200 to $1,800 for mitigation is not rattled by the inspection report. They're ready to keep the deal moving.

My own house tested over 16 pCi/L. I had Corey at Central Iowa Radon install the system. They were easy to work with, priced fairly, and the fans carry a 10-year warranty. The house was done in a day. I didn't lose sleep over the number because I understood what the fix was and what it cost.

Sellers who test before listing, remediate when the reading warrants it, and can show buyers a post-mitigation report are in a meaningfully stronger position at the table. You control the disclosure, the timeline, and the narrative.

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