Backyard project permits in Seattle, WA
Seattle is stricter than the model code on sheds (120 sq ft of roof, not 200 of floor) and looser on fences (8 ft before a permit).
Rules last checked by a person on October 19, 2026. Guidance only; confirm with Seattle before you build.
| Typical project | Permit? |
|---|---|
| Shed10 by 12 ft shed, 10 ft tall, no power | Yes: Building permit |
| Deck160 sq ft freestanding deck, 24 in high | Yes: Building permit |
| Fence6 ft wood fence in the back yard | No: no permit as described |
| Garage24 by 20 ft detached garage with lights | Yes: Building permit, Electrical permitConfidence: medium |
| ADU650 sq ft detached backyard cottage | Yes: Construction permit (addition/alteration) |
Check your exact lot
Permit office
Seattle Residential Code (R105.2 as amended) and Land Use Code, SMC Title 23.
- Seattle Services Portal
- SDCI common projects
- SMC 23.44, Neighborhood Residential
- Phone: (206) 684-8600