Snohomish County, WA Accessory Structures: Garage Conversions (2026)
Garage conversion rules in Snohomish County, WA, sometimes called garage-to-ADU or accessory living unit conversions, govern permits, ceiling height, egress, and parking replacement.
Key Facts
- Treated as
- Accessory dwelling unit
- Code section
- SCC 30.28.010
- Max floor area
- 1,200 square feet
- Permit
- Building permit required
- Parking
- Off-street per ch. 30.26
Summary
Converting a garage into habitable space in unincorporated Snohomish County is treated as creating an accessory dwelling unit and must meet SCC 30.28.010 ADU standards, including the 1,200-square-foot cap, water/sewer capacity, and off-street parking.
Accessory dwelling units are permitted uses in the urban zones pursuant to SCC 30.22.100 on lots with a single family, single family attached, or duplex dwelling. The floor area of an accessory dwelling unit shall not exceed 1,200 square feet.
Official source re-checked September 8, 2026: no newer edition of the code had been published (publisher’s edition: current through legislation passed August 12, 2026).
Full Breakdown
There is no separate 'garage conversion' allowance; adding a kitchen and living space to a garage creates an ADU subject to SCC 30.28.010. The unit must be on the same lot as the principal single-family, single-family-attached, or duplex dwelling, may not exceed 1,200 square feet of floor area, and must show physical and legal access to potable water plus adequate sewer or septic capacity. Off-street parking must comply with chapter 30.26 SCC. A building permit and inspections are required to convert the space to habitable use, and the lost garage parking may need to be replaced. Cities in the county apply their own conversion rules.
Violations & Fines
An unpermitted garage conversion used as a dwelling is a code violation; the county may require permits, inspections, or reversion to non-habitable use, with civil penalties for continuing violations.
Frequently Asked Questions
Can I convert my garage into an apartment?
Is a permit required to convert a garage?
Sources & Official References
Other rules in Snohomish County
Compare Snohomish County to another location·View the Washington accessory structures overview
See something wrong?
Help us keep this page accurate. If you notice an error or outdated information, let us know.