The Short Answer
Wisconsin regulates radon primarily through mandatory real estate condition disclosures and public health education coordinated through a statewide network of regional information centers. Under Wisconsin Statutes Chapter 709, residential sellers must complete a statutory Real Estate Condition Report disclosing known environmental hazards, including historical radon test results and installed mitigation equipment. Wisconsin does not operate a direct state licensing program for radon mitigators or testing specialists, pointing consumers to national NRPP and NRSB certification registries. In residential construction, the Wisconsin Uniform Dwelling Code mandates foundation sealing and sub-slab moisture barriers that provide passive soil-gas protection.
Testing Requirements
Indoor radon testing is voluntary for private single-family homeowners and residential landlords in Wisconsin; the state does not compel property owners to test existing dwellings prior to occupancy or sale. Similarly, Wisconsin statutes do not mandate routine radon testing in public or private K-12 school buildings or commercial child care facilities, though the Wisconsin Department of Health Services (DHS) and local public health divisions actively encourage school administrators to test voluntarily using ANSI/AARST school measurement protocols.
Real-Estate Disclosure
Real estate disclosure is governed by Wisconsin Statutes Chapter 709 (§§ 709.01 to 709.08). Under Wis. Stat. § 709.02, sellers of residential real estate (1 to 4 dwelling units) must deliver a completed Real Estate Condition Report (RECR) to prospective buyers within 10 days of accepting a purchase offer. The statutory disclosure form specifically requires sellers to disclose known environmental defects, including elevated radon gas levels, prior test reports, and whether an active or passive mitigation system is installed on the property. Failing to disclose known radon defects exposes sellers to statutory rescission rights and financial liability, though the law does not compel sellers to test untested homes.
Mitigator & Tester Certification
Wisconsin has no state licensing requirement for radon measurement technicians or mitigation contractors, per the Wisconsin Department of Health Services, verified November 2026. The state maintains no state-administered radon licensing board or regulatory credential. Instead, Wisconsin DHS officially directs homeowners, buyers, and local building officials to hire professionals certified through the two national proficiency programs recognized by the EPA: the National Radon Proficiency Program (NRPP) and the National Radon Safety Board (NRSB). Contractors must comply with local municipal building and electrical trade permits when modifying foundations or wiring mitigation fans.
New Construction
Construction standards in Wisconsin are governed by the Uniform Dwelling Code (UDC), codified in Wisconsin Administrative Code SPS Chapter 321. While SPS Chapter 321 does not universally mandate continuous passive radon vent pipes statewide, it enforces stringent sub-slab moisture and soil-gas retarder standards—including granular base courses and 6-mil polyethylene vapor membranes—alongside foundation waterproofing requirements that limit soil gas infiltration. Furthermore, individual municipalities and tribal jurisdictions (such as Forest County Potawatomi) have adopted model codes such as IRC Appendix F requiring complete passive radon-resistant new construction.
Radon Zones & the Action Level
According to the EPA Map of Radon Zones, Wisconsin features extensive EPA Zone 1 (High Potential) coverage across southern, eastern, and central counties—including Dane (Madison), Waukesha, Rock, Dodge, and Fond du Lac—where predicted average screening levels exceed 4.0 pCi/L. Remaining northern and western counties fall within Zone 2 (Moderate Potential, 2.0 to 4.0 pCi/L). Wisconsin DHS enforces the federal EPA action level of 4.0 pCi/L, noting that approximately one in three tested Wisconsin homes exhibits concentrations above this threshold. For complete geological risk details, visit our EPA Radon Zone Map guide.
The State’s Radon Program
The state’s official public health initiative is the Wisconsin Department of Health Services Radon Program, administered in partnership with local public health agencies through a network of 16 regional Radon Information Centers (RICs). The RIC network provides local testing advice, distributes subsidized test kits, and assists residents with interpreting test scores. Homeowners and contractors can locate their nearest regional information center and order test kits through the official Wisconsin DHS Radon Program portal or by calling the state radon line at 608-266-1120.
Sources & Limits
This regulatory summary is provided for educational and informational purposes only and does not constitute formal legal, building code, or engineering guidance. Statutory disclosure mandates and dwelling codes are subject to legislative amendment. Real estate buyers, sellers, landlords, and contractors should verify current rules directly with the Wisconsin Department of Health Services or a licensed real estate attorney.
Official Sources: Wisconsin Statutes Chapter 709; Wisconsin Administrative Code SPS Chapter 321; Wisconsin Department of Health Services (DHS); U.S. Environmental Protection Agency.
To examine how Wisconsin’s regulatory approach compares to other states, consult our comprehensive guide to radon regulations across the United States or inspect the EPA Radon Zone Map.
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