New construction radon features are cheaper to add while a house goes up than after. EPA calls them an inexpensive addition to the total cost of the house [1]. Iowa now requires a basic version in new one- and two-family homes. Here's what that rule covers, what the features are, and why testing still matters.
The Iowa rule
Iowa HHS says that beginning July 1, 2026, the state building code requires new one- and two-family homes to include a passive radon method from Appendix AF of the 2021 International Residential Code [2]. It applies only to homes started after the requirement took effect [2]. Questions about the code go to the Department of Inspections, Appeals and Licensing (DIAL) building code bureau at 515-725-6145 [2].
Before that date, HHS counted 11 jurisdictions that already required radon-resistant construction, including Johnson and Linn counties and the cities of Iowa City and North Liberty [2]. Iowa's mitigation rule exempts people who install passive systems, alone or as part of radon-resistant construction, from the mitigation credential [3].
The five builder features
EPA's builder page lists five basic features [4]:
- A 4-inch layer of clean, coarse gravel under the slab so soil gas can move.
- Heavy plastic sheeting or a vapor retarder over the gravel.
- A 3- or 4-inch solid PVC vent pipe from the gravel up through the house and roof, labeled "Radon System."
- Sealing and caulking of openings and cracks in the foundation floor and walls.
- An electrical junction box in the attic in case a fan is needed later.
Test after you move in
EPA says that if your home has a passive system, you should test it right after moving in to make sure levels are below EPA's guideline [1]. If the result is high, a fan can be added to pull radon from the soil into the vent pipe [1]. Iowa's rule says converting a passive system to an active one must be done by a credentialed person [3]. See radon testing and radon fan replacement.
FAQ
Does a passive pipe mean my home is safe?
Not on its own. EPA says the only way to know whether your new home has a radon problem is to test [1].
What does adding a fan cost?
We didn't find a published price for adding a fan to an existing passive pipe, so ask for a written quote. Under Iowa's rule, the conversion has to be done by a credentialed person unless you live in the home [3]. For full systems, see radon mitigation cost.
Get a quote
Tested high in a new home? Ask about adding a fan.
We're a referral service, not a contractor. We send mitigation requests only to contractors on Iowa HHS's current credentialed list and testing requests only to state-certified radon measurement specialists, but we don't otherwise vet them, a referral is not an endorsement, and independent contractors may pay us for referrals.
Sources
- U.S. EPA, How to Address Radon When Building a New Home, last updated Aug 17, 2026. https://www.epa.gov/radon/how-address-radon-when-building-new-home
- Iowa HHS, Radon Resources (fetched Nov 11, 2026). https://hhs.iowa.gov/health-prevention/providers-professionals/radiological-health/radon/radon-resources
- Iowa Administrative Code 641, Chapter 44, Radon Mitigation (ARC 0290D, IAB 5/13/26, effective 7/1/26). https://www.legis.iowa.gov/docs/iac/chapter/641.44.pdf
- U.S. EPA, Radon-Resistant Construction Basics and Techniques, last updated Aug 6, 2026. https://www.epa.gov/radon/radon-resistant-construction-basics-and-techniques