Accessory Structures in Portage County, WI (2026)
2 rules for unincorporated Portage County, Wisconsin.
Verified from official government sources
ADU Rules
In the towns of unincorporated Portage County, an accessory dwelling unit can only get a holding-tank special exception under Code § 7.9.9(5)(c) if a code-compliant private sewage system already serves the property. Code § 7.9.40(3) defines an ADU as a smaller, detached dwelling on the same lot as a single-family home, and the Board of Adjustment decides every request individually.
Accessory Dwelling Units in Portage County, WI
Significant RestrictionsPortage County Code § 7.9.9(5)(c)
(c)A sanitary permit for the installation, modification, or replacement of a holding tank, may be issued provided a special exception is approved by the Portage County Board of Adjustment as provided below. ... The following may be permitted by special exception:1.An accessory dwelling unit (ADU) or accessory use if a code compliant POWTS already exist on the property. A holding tank installed ...
Shed & Carport Rules
In the R2 Single Family Residence District of unincorporated Portage County, sheds and other accessory buildings are capped at 2,800 square feet on lots under two acres and 3,200 square feet on larger lots. Design must match the house, height cannot exceed 20 feet, and no commercial activity may take place inside.
Accessory Building Size Limits in Portage County
Some RestrictionsPortage County Code § 7.1.2(1)(b)4
4.Accessory buildings, including private garages and buildings clearly incidental to the residential use of the property, provided, however, that no accessory building may be used as a separate dwelling unit. Calculation of square footage of accessory buildings for each site will include the total of all detached garage space and similar detached structures. This calculation will be measured ba...
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