Accessory Structures in Jefferson County, WI (2026)
3 rules for unincorporated Jefferson County, Wisconsin.
Verified from official government sources
ADU Rules
An accessory dwelling unit in unincorporated Jefferson County needs its own conditional use permit and must follow real limits: one ADU per lot, no more than two bedrooms, a 1,000-square-foot cap, and the principal home must already exist. Section 22-588 lets an ADU be attached or built as a detached structure, including over a garage.
Jefferson County ADU Zoning Standards
Some RestrictionsJefferson County Code § 22-588(b)(1)-(4)
(1)The principal structure for the underlying district shall be present and constructed prior to an accessory dwelling unit.(2)No more than one accessory dwelling unit may be permitted on any lot.(3)Accessory dwelling units cannot have more than two bedrooms and may not exceed 1,000 sq. ft. in size.(4)Accessory dwelling units may be permitted either attached to the principal residence or in a d...
ADU Owner Occupancy
An accessory dwelling unit in unincorporated Jefferson County cannot be sold off separately from the main house, and Section 22-588 requires the property owner to actually live in either the principal home or the ADU. Before the county issues a building permit, the owner must record a deed restriction locking in both promises.
Jefferson County ADU Owner-Occupancy Rule
Significant RestrictionsJefferson County Code § 22-588(b)(9),(10),(13)
(9)Accessory dwelling units cannot be sold separately or transferred from the principal residence on the lot, nor from the lot on which the ADU sits.(10)The property owner must occupy either the principal structure or the accessory dwelling unit as their primary residence. ... (13)Prior to the issuance of a permit for the construction of the accessory dwelling unit, the owner(s) shall file a de...
Shed & Carport Rules
In unincorporated Jefferson County, driveways, walks, patios, pools and storage buildings grouped as residential accessory uses cannot cover more than 500 square feet of ground area combined. Coverage beyond that threshold is reclassified as extensive parking or storage under a different zoning category.
Jefferson County Shed and Accessory Coverage Limit
Some RestrictionsJefferson County Code § 22-7
(1)The term "residential accessory uses and buildings" includes driveways, walks, gardens, patios, pools, storage buildings and enclosures, provided that total ground area covered by buildings in this category does not exceed 500 square feet. More extensive coverage falls under extensive parking or storage.
All Jefferson County ordinances
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