Do I Need a Permit to Build an ADU in Wisconsin?
Accessory dwelling units require building permits, zoning approval, and may require variances depending on your municipality's zoning code.
Yes, you typically need a permit. Requirements vary by municipality. Check with your local building department for specifics.
Where to Apply
Permit requirements, fees, and processing times vary by municipality. Check the specific requirements for your location:
Browse all jurisdictions →Frequently Asked Questions
Are ADUs allowed in Wisconsin?
ADU regulations vary by municipality. Some cities (like Madison) have adopted ADU-friendly ordinances. Others restrict or prohibit them through single-family zoning. Check your local zoning code.
What permits do I need for an ADU?
Building permit, electrical, plumbing, and HVAC permits. You may also need a zoning variance or conditional use permit depending on your municipality.
How much does an ADU cost to build?
ADU construction in Wisconsin typically costs $100,000-$250,000 for a new detached unit. Garage conversions can be $50,000-$100,000.
Building in multiple cities?
See permit requirements for any Wisconsin municipality instantly. Compare fees, timelines, and processes side by side across your active jurisdictions.