Accessory Structures in Wisconsin (2026)

Marathon County zoning flatly bars using a detached garage, shed, or other accessory building as a separate dwelling…

In the City of Mosinee, an accessory building on a residential lot, a garage, shed or similar structure, cannot double…

De Pere allows one backyard cottage, a detached accessory dwelling unit, per lot occupied by a detached house under…

Green Bay allows one accessory dwelling unit per lot behind the main house, capped at 1,000 square feet, but only with…

New Berlin allows accessory dwelling units only inside the B-2, B-3 and B-5 business districts attached to the…

Outagamie County caps in-home accessory apartments at 600 square feet, requires the owner to live on-site, and limits…

In the towns of unincorporated Portage County, an accessory dwelling unit can only get a holding-tank special exception…

Unincorporated Waukesha County towns allow an in-law unit as a conditional use in Residential, Agricultural, B-1 and…

Appleton allows one attached or detached accessory dwelling unit plus one junior ADU per lot in the R-1A, R-1B, R-1C…

The Village of Ashwaubenon defines an Accessory Dwelling Unit in Sec. 17-3-200 of the Zoning Code (Chapter 17) as 'a…

ADUs in unincorporated Dane County are permitted in appropriate zoning districts under Chapter 10. ADUs must be…

Fitchburg allows one accessory dwelling unit per lot under § 22-230, capped at 75 percent of the principal home's floor…

An accessory dwelling unit in unincorporated Jefferson County needs its own conditional use permit and must follow real…

Kenosha County permits one Accessory Living Unit per single-family home, capped at 600 square feet and two occupants…

Madison lets a zoning lot carry one attached accessory dwelling unit or up to two detached ADUs under Madison General…

Middleton allows one accessory dwelling unit on a single- or two-family lot, attached or detached, but caps its size at…

Milton allows one accessory dwelling unit per single-family lot under City of Milton Code of Ordinances Sec…

Milwaukee allows one accessory dwelling unit per residential parcel, but only as a limited use tied to owner-occupancy…

Racine County allows one in-law suite as an accessory use in single-family homes across eleven zoning districts, capped…

Unincorporated Sauk County does not zone a stand-alone accessory dwelling unit; Section 7.059 instead permits a…

Wausau allows accessory dwelling units on a single-family lot under Municipal Code § 23.03.28(6), capping occupancy at…

Wauwatosa allows one accessory dwelling unit per lot on properties with a detached, semi-detached, attached, or…

West Allis allows one accessory dwelling unit per lot as a limited accessory use in most residential and several…

Winnebago County zoning allows a mother-in-law suite as an accessory use only if it sits entirely inside the principal…

Fitchburg's zoning code caps most lots at one accessory dwelling unit and bills new utility hookups like a brand-new…

Madison prices an accessory dwelling unit at the Multi-Family park impact fee rate, not the higher Single-Family rate…

Sauk County does not charge an ADU impact fee; instead, Section 7.059 requires the owner of an approved temporary…

An accessory dwelling unit in unincorporated Jefferson County cannot be sold off separately from the main house, and…

An accessory dwelling unit sharing a lot with a single-family home in Wausau requires the principal building to be…

Winnebago County zoning defines a mother-in-law suite as quarters accessory to, and used by, immediate relatives of the…

A guesthouse in unincorporated Waukesha County can never be leased or rented for human occupancy: Sec. 3.20 limits it…

Kenosha County limits who can live in an Accessory Living Unit: the occupant must be a resident related by blood…

Sauk County's temporary secondary dwelling permit is not a rental license: Section 7.059 issues it only to the property…

Winnebago County bars a mother-in-law suite from having its own address, utility meter, or separate entrance: the…

Appleton caps a detached shed, garage or gazebo on an R-1A, R-1B, R-1C or R-2 lot at 1,600 combined square feet, 15…

Ashwaubenon requires a building permit before erecting any accessory building, including sheds, and caps their…

Backyard sheds in the City of Beloit split into two categories under § 9.24(5) of the Code of Ordinances: a…

Brown County lets storage sheds and other accessory structures sit inside the 20-foot critical slope setback, but caps…

Burlington caps accessory building size on a sliding scale tied to lot area, from 720 square feet on lots up to 10,000…

A shed of 120 square feet or less on a non-permanent foundation needs no zoning permit in unincorporated Dane County…

Any shed, detached garage, gazebo, pergola or other accessory structure in De Pere needs a building permit from the…

Fitchburg, Wisconsin caps a detached garage, carport or storage building over 400 square feet at the height of the…

In the recreational-residential shoreland district of unincorporated Fond du Lac County, a garage, shed, storage…

In unincorporated Grant County, Wisconsin, an accessory structure in the flood-fringe must be constructed on fill with…

Green Bay allows two detached accessory structures on a one- or two-family lot under Section 44-590 and Table 44-4. The…

In the City of Janesville, a detached garage or accessory building must sit at least five feet from any other building…

In unincorporated Jefferson County, driveways, walks, patios, pools and storage buildings grouped as residential…

Kenosha exempts one-story residential sheds, playhouses and similar accessory buildings of 120 square feet or less from…

In unincorporated Kenosha County towns, any accessory building bigger than 150 square feet or taller than 15 feet needs…

Little Chute caps detached garages at 960 square feet and other accessory buildings at 200 square feet, limits height…

Madison caps the total footprint of sheds and other accessory buildings on residential and mixed-use lots at 1,000…

Detached sheds and garages in Marathon County's Urban Residential district top out at 1,400 square feet, need a 15-foot…

Middleton caps all detached accessory buildings on a lot, sheds, garages, workshops and similar structures, at 1,000…

A shed or storage building in the City of Milton can sit in the side or rear yard setback, but not the front, only if…

Milwaukee caps sheds at 150 sq ft, bars them from front yards, and sets a 4-foot rear setback and 8-foot sidewall…

Milwaukee County has no shed ordinance. Detached sheds and garages are exempt from the Wisconsin Uniform Dwelling Code…

A residential lot in Mosinee may hold the principal house plus a detached or attached garage and one additional…

Neenah's published Garages and Storage Sheds handout from the Community Development Department limits each property to…

New Berlin treats sheds of 144 square feet or less as a distinct accessory building class under Sec. 275-42 B(2): they…

Outagamie County zoning caps detached sheds and other accessory buildings at one per lot beyond a garage, bars them…

In the R2 Single Family Residence District of unincorporated Portage County, sheds and other accessory buildings are…

A shed under 36 square feet skips Racine County's zoning permit, but every accessory building on a lot counts toward an…

Rothschild limits accessory structures like sheds and detached garages under Village Code § 590-96.1: only one detached…

In the Single Family Residential district, Sauk County caps a shed or other principal accessory structure's floor area…

Utility sheds 80 square feet or smaller (roughly 8 by 10 feet) do not require a building permit in Sun Prairie. Sheds…

Sheds and other accessory buildings in unincorporated Walworth County are capped by lot size under Walworth County Code…

Waukesha caps detached sheds and accessory buildings at one story and 720 square feet total, dropping to 150 square…

In unincorporated Waukesha County towns, a lot is limited to two accessory buildings and a total footprint of 600 sq ft…

Sheds in Wausau are accessory structures under Title 23 of the Wausau Municipal Code. The City of Wausau Inspections…

Wauwatosa lets you skip a building permit for a storage shed, play structure or other accessory structure only if it…

West Allis limits a detached shed ('Other Accessory Building') to 300 square feet and 15 feet of height, set back 60…

A carport counts as a residential garage under Chapter 23's town/county zoning, so it needs a zoning permit and must be…

Dane County's zoning code flatly bars turning a garage or other accessory building into living space. Section 10.004(2)…

Converting a detached garage into living space is allowed under Appleton Municipal Code Sec. 23-55(f)(3) as an…

Wisconsin's Uniform Dwelling Code (Wis. Stat. ch. 101 and SPS 320-325) sets statewide construction standards for one…

Milwaukee does not permit tiny homes on wheels as permanent dwellings. Tiny houses on foundations must meet the…

Tiny homes on foundations are allowed in Madison if they meet WI Uniform Dwelling Code and zoning minimum dwelling…

Waukesha County town zoning effectively blocks most tiny homes: any single-family dwelling must have 1,100 sq ft…

Wauwatosa has no ordinance called "tiny homes," but its Cottage Court standards, which the code itself labels a…