Green Bay, WI Accessory Structures: ADU Rules (2026)
ADU rules in Green Bay, WI, also called accessory dwelling unit regulations or granny flat ordinances, cover setbacks, owner-occupancy, parking, and permit requirements.
Key Facts
- Cap
- One ADU per parcel
- Size limit
- 1,000 sq ft max
- Occupancy
- Owner must live on-site
- STR use
- ADUs cannot be short-term rentals
- Approval
- Conditional use permit required
Summary
Green Bay allows one accessory dwelling unit per lot behind the main house, capped at 1,000 square feet, but only with a conditional use permit and owner-occupancy of one unit.
Accessory dwelling units are permitted in conjunction with a primary detached single-family dwelling, two-family dwelling (duplex or semi-detached) or single-family attached dwellings (townhouses). They are not permitted in conjunction with multiple-family or mixed-use structures.(2)There shall be no more than one accessory dwelling unit on a parcel/lot...(4)An accessory dwelling unit shall not be permitted to be used as a short term rental.(5)b.Not contain more than 1000 square feet of gross floor area or greater than the established primary residential building, whichever is less.
Full Breakdown
An ADU is permitted with a single-family, duplex, or townhouse dwelling, never with multifamily or mixed-use buildings, and only one is allowed per parcel. Either the primary residence or the ADU must be the owner's permanent residence, and the ADU cannot be used as a short-term rental. It must sit behind the principal dwelling's front facade, cannot exceed 1,000 square feet or the primary building's size, whichever is smaller, and must match the primary home's height and architectural style. One dedicated parking space and a walkway to the street are required, and the parcel cannot be subdivided between the two units. A conditional use permit with Plan Commission review is required.
Violations & Fines
Building or renting out an unapproved ADU is a zoning violation; the City can require removal or bring the property into compliance through standard Code enforcement, since no separate ADU penalty is set.
Frequently Asked Questions
Can I rent my Green Bay ADU out on Airbnb?
How big can a Green Bay ADU be?
Sources & Official References
Other rules in Green Bay
How Green Bay compares: Easiest Cities to Build an ADU·Compare Green Bay to another location·View the Wisconsin accessory structures overview
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ADU Rules in Nearby Cities
How other cities in Brown County handle adu rules.