Winnebago County, WI Accessory Structures: ADU Rental Restrictions (2026)
Key Facts
- No separate entrance
- Sole entry must be shared
- No separate meter/address
- Bars independent utility/address
- Floor-area perk
- Exempt from accessory area cap
- Governing section
- Ch. 23 § 23.8-474
Summary
Winnebago County bars a mother-in-law suite from having its own address, utility meter, or separate entrance: the features that would let it function as an independently rented unit.
The residential quarters must be contained entirely within the principal structure and shall not be recognizable from the outside as a separate dwelling unit utilizing such characteristics as a separate address, separate utility meter, or a separate entrance which is the sole means of entry into the unit.
(a)Accessory floor area. A mother-in-law suite is exempt from counting towards the maximum allowed accessory floor area.
Full Breakdown
Ch. 23 § 23.8-474 requires a mother-in-law suite's residential quarters to stay entirely within the principal structure and forbids it from being recognizable from the outside as a separate dwelling unit through a separate address, a separate utility meter, or a separate entrance that is the sole means of entry into the unit. That structural bar keeps the suite tied to the main home rather than functioning as a standalone rental. In exchange, the code doesn't count a mother-in-law suite's floor area toward the parcel's overall accessory-structure area cap. The rule applies only in towns that have adopted Ch. 23 by resolution (§ 23.1-3) and never inside Oshkosh, Neenah, Menasha, or any other incorporated city.
Violations & Fines
Adding a separate entrance, meter, or address to a mother-in-law suite is a zoning violation under § 23.14-3, triggering a stop-work order and forfeiture plus prosecution costs under § 23.14-9.
Frequently Asked Questions
Can I rent out a mother-in-law suite in Winnebago County as a separate unit?
Does building a mother-in-law suite count against my accessory building limit?
Sources & Official References
Other rules in Winnebago County
Compare Winnebago County to another location·View the Wisconsin accessory structures overview
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