How big can a Shoreline ADU be?
✓ Verified against code · August 19, 2026
1,200 sq ft — above the state's 1,000 floor — and an interior ADU on its own floor under a common roof may exceed even that.
Citation: SMC 20.40.210(C)
How current is this?
Shoreline’s ADU rules run under SMC 20.40.210 (Shoreline Municipal Code) (Ordinance 1027 (amended by Ord 1043)). Shoreline rewrote its ADU section in January 2025 (Ord 1027), then went further than the state ever asked in August 2025: Ordinance 1043 eliminated minimum vehicle parking requirements for everything, citywide. We verified this answer against primary sources on August 19, 2026, and every change we catch is logged in the changelog.
More Shoreline ADU questions
- Do I need parking for an ADU in Shoreline?
- How long does a Shoreline ADU permit take?
- How many ADUs can I add in Shoreline?
- Can I sell a Shoreline ADU separately?
All Shoreline ADU rules → · Compare Washington cities →
Not legal advice — lot-specific overlays can change the answer for your parcel. The citation above points at the governing code section; check it, or ask the city to confirm.