ADU Regulations in Bellevue, Washington
In King County across Lake Washington from Seattle, Bellevue maintains stringent ADU design guidelines. Despite Washington's HB 1337, the city enforces a 5-year owner occupancy requirement and detailed design review for exterior modifications.
Below is a summary of the key zoning rules applicable to Accessory Dwelling Units in Bellevue 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 | Required |
Additional Local Requirements for Bellevue
- ADU allowed in single-family zones
- Minimum 200 sq ft
- 5-year owner occupancy required
- Design review for exterior changes
📥 Download the Complete Bellevue 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 Bellevue, Washington.
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Can I build an ADU in Bellevue?
Bellevue allows ADUs under strict design guidelines. The city requires owner occupancy for the first 5 years after permit issuance.
How big can my ADU be in Bellevue?
What is the maximum ADU size allowed in Bellevue? ADUs in Bellevue 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 Bellevue planning department before designing your project.
What about setbacks and other requirements in Bellevue?
What are the setback requirements for an ADU in Bellevue? ADUs in Bellevue 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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