ADU Regulations in Sammamish, Washington
In eastern King County, Sammamish allows ADUs under Washington's HB 1337 framework. The city's affluent lakeside neighborhoods apply design review standards to new accessory units.
Below is a summary of the key zoning rules applicable to Accessory Dwelling Units in Sammamish as of 2026. Regulations are governed by Washington's HB 1337 (2023) which limits local ADU restrictions statewide.
| Regulation | Requirement |
|---|---|
| Maximum Size | 1,000 sq ft |
| Property Setbacks | 5 ft rear, 5 ft side |
| Extra Parking Required | Not required (near transit) |
| Owner Occupancy | Not required |
Additional Local Requirements for Sammamish
- ADU by right in residential zones
- Minimum 200 sq ft
- WA HB 1337 limits local restrictions
📥 Download the Complete Sammamish ADU Cheat Sheet
Get the step-by-step permit checklist, official government forms, direct planning department contacts, and estimated fees — all in one printable PDF for Sammamish, Washington.
Download the Complete Sammamish ADU Cheat Sheet — $12Frequently Asked Questions About ADUs in Sammamish
Can I build an ADU in Sammamish?
This Washington city follows HB 1337 which limits local ADU restrictions. Parking may be waived near transit.
How big can my ADU be in Sammamish?
What is the maximum ADU size allowed in Sammamish? ADUs in Sammamish can be up to 1,000 square feet, subject to the property's zoning and lot coverage limits. Always confirm the exact allowed size with the Sammamish planning department before designing your project.
What about setbacks and other requirements in Sammamish?
What are the setback requirements for an ADU in Sammamish? ADUs in Sammamish generally require setbacks of 5 ft rear, 5 ft side. California state law (AB 68) limits local setback requirements to 4 feet for existing structures, but always verify with local zoning.
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