Dane County, WI Accessory Structures: Shed & Carport Rules (2026)
Shed permit rules in Dane County, WI, also referred to as storage shed, backyard shed, or accessory building regulations, set size limits, setbacks, and when a building permit is required.
Key Facts
- No-permit threshold
- 120 sq ft or less, non-permanent foundation
- SFR-08 height cap
- 12 feet (16 ft with CUP)
- SFR-08 rear setback
- 10 feet (2.5 ft if near house)
- Lot coverage cap
- 100% of principal residence footprint
- Living-space rule
- Accessory buildings can't be used as housing
Summary
A shed of 120 square feet or less on a non-permanent foundation needs no zoning permit in unincorporated Dane County, as long as it still meets setback, height and lot coverage rules. In the SFR-08 district, larger accessory buildings top out at 12 feet, sit at least 10 feet off the rear line, and can't exceed the footprint of the house.
(b) Exceptions. Zoning permits under this chapter are not required for accessory buildings equal to or less than 120 square feet on non-permanent foundations, provided they meet all setback, height, and lot coverage requirements. ... (5) Setbacks and required yards. ... (c) Rear yard. ... 3. Except as exempted in 4 below, accessory buildings must be at least 10 feet from the rear lot line. 4. Accessory buildings in the rear yard that are at least 10 feet from the principal residence must be at least: a. 4 feet from any rear lot line on lots 60 feet or more in width, or b. 2.5 feet from any rear lot line on lots less than 60 feet in width. (6) Building height. ... (b) Accessory buildings. Unless under an approved conditional use permit under s. 10.251(3)(a), residential accessory buildings shall not exceed 12 feet in height. (7) Lot coverage and building area. ... (b) Accessory buildings cannot exceed 100% of the area of the footprint of the principal residence.
Full Breakdown
Ch. 101(1)(b) exempts small sheds from the zoning permit process entirely: accessory buildings of 120 square feet or less on non-permanent foundations don't need a permit, provided they still comply with the setback, height, and lot coverage standards for the zoning district. Anything larger triggers the standard zoning permit under ch. 101(1)(a), filed with a site plan, floor plan, and elevation drawing. Dimensional limits vary by district; in the SFR-08 (Single-Family Residential, Small Lots) district, ch. 5 feet on lots under 60 feet wide if the building sits at least 10 feet from the principal residence.
Ch. 251(6)(b) caps accessory building height at 12 feet unless the owner secures a conditional use permit under ch. 251(3)(a) for a taller structure between 12 and 16 feet. Ch. 251(7)(b) further limits accessory buildings to no more than 100% of the footprint of the principal residence, a shed or garage can't be larger on paper than the house it serves. County-wide, ch. 102(2)(a) adds that a principal building generally must exist or be under construction before an accessory building goes up, that accessory buildings may not be used as living space except for accessory dwelling units, and that plumbing fixtures are prohibited in ordinary accessory buildings.
These rules apply only in unincorporated towns that adopted county zoning; Madison, Sun Prairie, and Dane's other cities enforce their own building and zoning codes for sheds.
Violations & Fines
Erecting a shed over 120 square feet without a zoning permit, or building one that violates the district's height, setback, or lot-coverage cap, is a zoning violation the administrator can enforce, and it will also block the property from getting any other zoning permit until resolved. A shed placed on a permanent foundation loses the small-shed exemption regardless of size and needs a permit.
Frequently Asked Questions
Do I need a permit for a small backyard shed in Dane County?
How tall can a shed be in the SFR-08 district?
How close to the rear property line can I build a shed?
Can my shed be bigger than my house?
Sources & Official References
Other rules in Dane County
How Dane County compares: Shed Permit Requirements by City·Compare Dane County to another location·View the Wisconsin accessory structures overview
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