Accessory Structures in Washington County, MN (2026)
4 rules for unincorporated Washington County, Minnesota.
Verified from official government sources
ADU Rules
An accessory apartment in unincorporated Washington County needs a Certificate of Compliance in the Shoreland Management Overlay District, is capped at one per single-family dwelling, and the underlying home must be owner-occupied under Development Code Section 2.1.
Washington County Accessory Apartment Permit Rules
Significant RestrictionsWashington County Development Code, Ch. 2, Sec. 2.1(1), (3)(A), (3)(C)
Accessory Apartments (1) Required Permit: Accessory Apartments are permitted within the Shoreland Management Overlay District with a Certificate of Compliance, provided that local ordinance allows Accessory Apartments within the underlying zoning district. (3)(A) More than one accessory apartment within a single family dwelling unit is prohibited. (3)(C) A separate curb cut for the accessory ap...
ADU Owner Occupancy
Washington County requires the primary structure containing an accessory apartment to be owner-occupied. Development Code Section 2.1(3)(B) states plainly that 'the structure in which an accessory apartment is located shall be owner occupied,' foreclosing rental of both units to non-owners.
Washington County Requires Owner-Occupancy for ADUs
Significant RestrictionsWashington County Development Code, Ch. 2, Sec. 2.1(3)(B)
(3)(B) The structure in which an accessory apartment is located shall be owner occupied.
Shed & Carport Rules
Washington County requires a building permit for nearly every accessory building, and caps shed size by lot acreage inside its Shoreland and St. Croix River Overlay Districts. A parcel under 1 acre is capped at 720 square feet of accessory structures; the limit rises with acreage to unlimited square footage past 20 acres for agricultural buildings.
Washington County Accessory Structure Permit, Size Rules
Some RestrictionsWashington County Development Code, Chapter Two §§ 1.2(1), 1.2(3)(B)
1.2 Accessory Structures (1) Required Permits. A building permit is required for all accessory structures except agricultural buildings on a farm as defined in Minnesota Statute 16B.61. A Certificate of Compliance is required for all agricultural buildings and accessory structures in the Shoreland Management Overlay District and the St. Croix River Management Overlay District. ... (3) The follo...
Garage Conversions
Washington County's Development Code flatly bans converting a garage into living space. Section 1.1(11) of Chapter Two prohibits using a cellar, garage, recreational vehicle, trailer, unfinished-exterior basement, or any other accessory building as a dwelling unit anywhere in the unincorporated county and its townships.
Washington County Bars Garage Living Conversions
Heavy RestrictionsWashington County Development Code, Chapter Two § 1.1(11)
(11) Dwelling Unit - Use Prohibited. The use of a cellar, garage, recreational vehicle, trailer, basement with unfinished exterior above or accessory building as a dwelling unit is prohibited.
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