If you have scrolled through active listings in West Des Moines this year, you may have run into a line buried in the agent remarks: the seller has no knowledge of radon, the buyer is welcome to test at their own expense, and the seller will not participate in mitigation or be informed of the results. It reads like a tidy way to keep both sides out of each other's business. It is not what Iowa's disclosure law actually requires, and it tends to protect the seller far less than the wording implies.
That single line is a decent entry point into a bigger problem with how most people think about radon in this city. The usual advice sorts houses by age and assumes the risk sorts the same way: old basement, worry more; new build, worry less. West Des Moines does not cooperate with that logic. A brand-new house going up in Jordan Creek can post the same reading as a house that predates the city's own founding as Valley Junction in 1893. The house's age alone does not tell you its radon level. Your leverage depends on where you are in the transaction and whether the paperwork in front of you is doing what it claims to do.
The Line in the Listing That Doesn't Do What It Says
Iowa's radon disclosure rules live in Iowa Code sections 543B.9 and 543B.18, administered through Iowa Administrative Code 193E Chapter 14 by the Iowa Real Estate Commission. The requirement is specific: if a seller has a known radon test result, they must disclose it, along with the date of the test. Sellers also have to acknowledge that they gave the buyer a copy of the Iowa Radon Home-Buyers and Sellers Fact Sheet, and the buyer has to acknowledge receiving it.
That "no knowledge, won't participate" remark only addresses one scenario: a house that has never been tested. It says nothing about a house that was tested at some point, maybe during a refinance, an insurance inspection, or a previous sale, where the result exists but never got mitigated. The PubMed Central study describes how Iowa closed exactly that gap in 2015. Before the amendment, only the seller received a copy of test results. After it, disclosure of the result to the buyer became mandatory regardless of what the number said. A seller who knows a prior reading and lets an agent write "no knowledge" into the remarks is not avoiding the disclosure requirement. They are creating a bigger problem for themselves if that prior result ever surfaces.
If you're a buyer working through a listing with that kind of language, it is worth asking directly whether any test has ever been run on the property, rather than taking the remark at face value.
Same City, Same Zone, No Correlation to Age
Iowa's radon problem is a geology story, not a construction-quality story. The soils across the state, including under West Des Moines, were deposited by retreating glaciers and carry unusually high concentrations of uranium, which decays into radon gas that moves upward through any gap it can find. That process does not care whether the foundation above it was poured last spring or a century ago.
| Neighborhood | Typical housing age | Common assumption | What actually happens |
|---|---|---|---|
| Valley Junction | Many homes built before 1939, some earlier | Old house, assume elevated risk | Can test high, but age itself is not the reason |
| Jordan Creek | New construction, ongoing development | New build, assume low risk | Can test just as high as older housing nearby |
| Westridge / Ashworth | Mix of established and newer construction | Depends on build year | Same pattern: results vary by house, not by era |
The city's own radon grant materials make this point directly, naming Jordan Creek, Valley Junction, and Westridge side by side and noting that homes in all three can test high regardless of when they were built. A finished basement does not block the gas. Homes without basements are not automatically safer. The only way to know what is happening in a specific house is to test that house.
What Actually Changed on July 1
According to Iowa HHS, Iowa's statewide building code now requires new single-family and two-family construction to include a passive radon mitigation system, based on the 2021 International Residential Code's Appendix AF. The requirement took effect July 1, 2026
Here is the part that matters specifically in West Des Moines: most of the city sits in Polk County, but the area around Jordan Creek extends into Dallas County. Polk County was already requiring radon-resistant construction in new builds before the statewide rule existed. That means a new-construction home going up in the Polk County side of the city, closer to Valley Junction and the historic core, likely had a passive system built in well before this summer's code change was ever on the books. Jordan Creek falls in the Dallas County portion of the city.
Either way, a passive system is not a guarantee. It reduces the pathways radon can use to enter the house, but it does not replace testing. Buyers comparing new construction against resale in this market should treat "the builder included a radon system" as a starting point, not a finished conversation.
What It Actually Costs, and Why the Range Swings So Wide
A standard sub-slab depressurization system, the most common fix across the metro, typically runs somewhere between $800 and $2,500 installed. That is a wide range, and the reason has nothing to do with the house's age. It comes down to foundation type. Sealing and ventilating an unfinished basement might run around $4,600. Encapsulating a crawl space without a slab can range anywhere from $1,500 to $15,000, depending on the size and condition of the space.
That is the same pattern showing up again. Risk and cost both track with the physical structure of the foundation and the soil underneath it, not with the decade the house was built or which established neighborhood it sits in.
The Grant Most Owners Don't Know to Ask About
West Des Moines runs its own Radon Mitigation Program, and it is worth checking before anyone pays out of pocket. The West Des Moines Radon Mitigation Program covers up to $5,000 per home, applied to both testing and the mitigation work itself, and the money does not need to be repaid. It is open to single-family homes, duplexes, and townhouses, whether owner-occupied or rented, as long as the rental has a valid rental certificate. Income eligibility is set at 80 percent of the area median income, with thresholds ranging from $64,150 for a single person up to $113,600 for a household of seven. Applicants also need to be current on their mortgage and property taxes, carry home insurance, and have no outstanding city fines.
The program has been active since January 1, 2025, and it applies inside city limits regardless of which neighborhood you're in. A house in Valley Junction and a house in Jordan Creek qualify under the same terms. If cost has been the reason you have put off testing a house you already own, this is the program to call before hiring anyone. The city's Housing Department can walk through the application at (515) 273-0770 or [email protected].
What This Means for Your Transaction
- If you're buying, request testing early in your inspection period rather than near the end.
- If you're selling and a prior test exists on the property, disclose it. The 2015 amendment removed any gray area here.
- If you're weighing new construction, ask which system the builder installed, whether it's active or passive, and whether the home falls on the Polk County or Dallas County side of the parcel line.
- If you already own the home and are just now thinking about testing, check your eligibility for the city's grant before assuming mitigation is an out-of-pocket cost.
A Few Questions Worth Answering Directly
If my new-construction home already has a passive radon system, do I still need to test? Yes. A passive system reduces the pathways radon can travel through, but it does not guarantee a reading below the EPA's action level of 4.0 pCi/L. Testing is still the only way to know what the house is actually doing.
Does the city's grant apply if I'm planning to sell rather than stay? The program is built around income eligibility and the property's standing, not your future plans for it. If you qualify and the home is within city limits, it can be used to test and mitigate before you list, which also gives you a clean result to disclose rather than an open question.
What happens if a test comes back high during my inspection period? Check the terms of your contract.
Radon in West Des Moines is not a story about old houses versus new ones. It is a story about soil, foundations, and whether the paperwork in front of you actually reflects what has or hasn't been tested. If you're weighing a purchase, a listing, or just trying to figure out what a line in an MLS remark actually means for your specific address, Christopher Lewis can walk through it with you before you're up against a deadline. Let's Connect.
This article is general information, not legal, tax or financial advice. Consult a qualified professional about your situation.
