Seattle, WA Accessory Structures: Shed & Carport Rules (2026)
Shed permit rules in Seattle, WA, also referred to as storage shed, backyard shed, or accessory building regulations, set size limits, setbacks, and when a building permit is required.
Key Facts
- Front-setback garage cap (1 space)
- 300 sq ft, 14-ft width
- Front-setback garage cap (2 spaces)
- 600 sq ft, 24-ft width
- Rear setback minimum
- 5 feet from rear property line
- Side setback option
- Recorded neighbor agreement or alley/rear proximity
- Governing section
- SMC 23.44.090(G)
Summary
SMC 23.44.090(G) lets garages and carports sit in a required setback under specific conditions: a front-setback garage is capped at 300 square feet and 14 feet wide for one space, or 600 square feet and 24 feet wide for two, and a rear-setback garage must stay 5 feet off the rear line.
G.Garages and carports1.Garages and carports may be located in a setback where parking is allowed in a setback as provided in subsections 23.44.160.D.4 and 23.44.160.D.5.2.Garages and carports may be located in a required side setback that abuts the rear or side setback of another lot if:a.The garage or carport is a detached structure and extends only into that portion of a side setback that is either within 40 feet of the centerline of an alley or within 25 feet of any rear lot line that is not an alley lot line; orb.An agreement between the owners of record of the abutting properties, authorizing the garage or carport in that location, is executed and recorded with the King County Recorder's Office.3.Garages and carports may be located in the rear setback provided they are not located within 5 feet of the rear property line.4.Garages and carports allowed in required setbacks shall comply with all of the following standards:a.The area of a garage or carport in front setbacks, is limited to 300 square feet with 14-foot maximum width if one space is provided, and 600 square feet with 24-foot maximum width if two spaces are provided.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Municipal Code: Supplement 44 Update 1).
Full Breakdown
090(G) governs where garages and carports may encroach into a required yard setback. 5. 2, a garage or carport may sit in a required side setback that abuts a neighboring lot's rear or side setback only if it is a detached structure within 40 feet of an alley centerline or within 25 feet of a non-alley rear lot line, or if the abutting property owners execute and record an agreement authorizing it with the King County Recorder's Office. 3 allows placement in the rear setback as long as the structure stays at least 5 feet from the rear property line.
4 then caps the size of any garage or carport placed in a front setback at 300 square feet and 14 feet of width for a single parking space, or 600 square feet and 24 feet of width for two spaces; roof eaves and gutters that project up to 2 feet are excluded from that size limit, and the roof of a setback garage or carport may not be used as a rear- or side-setback balcony or deck. 3 permits, no longer qualifies for the setback exception and must meet the full Table A setback instead.
Violations & Fines
Building a garage or carport larger than the 300-square-foot/14-foot (one space) or 600-square-foot/24-foot (two space) front-setback cap, placing it closer than 5 feet to a rear lot line, or locating it in a side setback without the recorded neighbor agreement required by SMC 23.44.090(G)(2)(b) is a zoning violation; SDCI will require the structure to be resized, relocated, or brought into full Table A setback compliance.
Frequently Asked Questions
How big can a garage be if it's in my front setback in Seattle?
Can I build a carport right on my rear property line?
Can a garage sit against my neighbor's side setback?
Sources & Official References
Other rules in Seattle
How Seattle compares: Shed Permit Requirements by City·Compare Seattle to another location·View the Washington accessory structures overview
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Shed & Carport Rules in Nearby Cities
How other cities in King County handle shed & carport rules.