5 county-level rules, plus city-specific rules for 1 city in Spokane County, Washington.
Verified from official government sources
Spokane County allows one accessory dwelling unit (ADU) per single-family lot. Detached ADUs are capped at 800 sq ft on the ground floor and 2 bedrooms, on lots of at least 10,000 sq ft. Attached ADUs are capped at 900 sq ft.
SCC 14.606 (Detached ADU standards)
The accessory dwelling unit shall contain no more than 2 bedrooms and shall measure no more than 800 square feet on the main (ground) floor. Only 1 accessory dwelling unit shall be allowed per lot with an existing single-family residence. Accessory dwelling units shall not be allowed on lots that are less than 10,000 square feet in size.
In unincorporated Spokane County, a one-story detached storage shed under 200 sq ft needs no building permit, but must still meet zoning setbacks. Total accessory-structure floor area is capped by lot size under Zoning Code Chapter 14.606.
SCC 14.606, Table 606-4 (Size Standards for Accessory Structures)
One accessory structure shall be permitted prior to the construction of a primary use. This structure is not for residential occupancy, business use, or outside vehicle repair.
Converting a garage or attached space into living quarters is treated as creating an accessory dwelling unit or added living area under Zoning Code Chapter 14.606. It needs a building permit and, if a separate unit, must meet ADU standards and keep required off-street parking.
SCC 14.606 (Attached ADU standards)
The accessory unit shall be a complete, separate housekeeping unit that is within or attached to the principal unit with a common wall(s). In no case shall it be more than 35% of the building's total livable floor area, nor more than 900 square feet, whichever is less.
Carports are accessory structures under Spokane County Zoning Code Chapter 14.606 and must meet residential setbacks (typically 5 ft side and rear) and lot-coverage limits. Garage and carport front/flanking-street setbacks are measured the same for attached and detached structures.
SCC 14.606 (Residential dimensional standards, Table 606 notes)
Setbacks are measured from the property line unless there is a border easement, in which case, the setback shall be measured from the back of the sidewalk. Front/flanking street setbacks for garages include both attached and detached structures.
Spokane County has no separate tiny-home ordinance. A permanent tiny house on a foundation is regulated as a single-family dwelling or accessory dwelling unit under Zoning Code Chapter 14.606; a tiny house on wheels is treated as a recreational vehicle and can't be used as a permanent residence in most
1 cities in Spokane County have their own accessory structures rules. Each link goes to that city's dedicated page with code citations.
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