What Is the Uniform Dwelling Code (UDC) in Wisconsin?

The Uniform Dwelling Code (UDC) is Wisconsin's mandatory statewide building code for one- and two-family dwellings, administered by the Department of Safety and Professional Services (DSPS) under SPS 320–325. Unlike commercial buildings, which have varying local adoption of building codes, the UDC applies uniformly across every municipality in Wisconsin. No city or county can adopt a more or less restrictive residential building code. The UDC covers structural requirements, fire safety, energy efficiency, plumbing, electrical, HVAC, insulation, ventilation, and accessibility for residential dwellings. It adopts elements of the International Residential Code (IRC) with Wisconsin-specific amendments — notably including frost depth requirements (48 inches in most of the state), energy efficiency standards suited to Wisconsin's climate, and specific radon mitigation requirements in designated radon zones. Municipalities are responsible for enforcing the UDC through local building inspection departments. They issue permits, conduct inspections, and ensure compliance. While municipalities cannot change the code itself, they can set their own permit fees, processing times, and administrative procedures. The UDC does not cover commercial buildings (regulated under SPS 361–366), agricultural buildings (generally exempt), or accessory structures under certain size thresholds (set by each municipality). Understanding the UDC is essential for any residential construction or remodeling project in Wisconsin.

Check Your Municipality

Permit requirements, fees, and exemptions vary by municipality. Verify the specifics for your location.