Spokane County, WA Accessory Structures: Garage Conversions (2026)
Garage conversion rules in Spokane County, WA, sometimes called garage-to-ADU or accessory living unit conversions, govern permits, ceiling height, egress, and parking replacement.
Key Facts
- Governing rule
- Attached ADU standards, SCC 14.606
- Size limit
- 35% of area or 900 sq ft
- Units allowed
- One accessory unit per lot
- Appearance
- Must look single-family
- Parking
- One extra off-street space
Summary
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.
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.
Full Breakdown
Spokane County does not have a standalone garage-conversion chapter; a conversion that creates a separate dwelling is regulated as an attached ADU under SCC 14.606. That unit must be a complete, separate housekeeping unit within or attached to the principal dwelling with a common wall, must be designed so the building still looks like a single-family residence with side or rear entrances, and cannot exceed 35% of the building's total livable floor area nor 900 sq ft. Only one such unit is allowed. Because a converted garage removes required parking, the county requires one additional off-street space for the new unit. All conversions require building permits for structural, electrical, and life-safety compliance.
Violations & Fines
Unpermitted garage conversions and illegal second units are zoning and building-code violations; Spokane County Building and Planning can require permits, corrections, or restoration.
Frequently Asked Questions
Can I convert my garage into an apartment in unincorporated Spokane County?
Do I need a permit to convert a garage?
Sources & Official References
Other rules in Spokane County
Compare Spokane County to another location·View the Washington accessory structures overview
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