ADU regulations | City of Bellevue

• Maximum size: An ADU may not exceed 1,200 sq ft or 40 percent of the combined gross floor area of the principal dwelling plus the ADU (excluding garage space) — whichever is greater.

  
  

• Parking requirements:

  • No parking is required if the ADU is under 1,000 sq ft or located within ½ mile of frequent transit service.

  • For ADUs 1,000 sq ft or larger, one parking space is required (unless the transit exemption applies).

  • For ADUs over 2,000 sq ft, one space is required for lots under 6,000 sq ft, and two spaces for larger lots.

    
    

• Detached ADUs (DADUs):Currently, the City of Bellevue allows attached and internal ADUs only. Detached ADUs are not yet permitted, but reforms are under consideration.

  
  

• All ADUs must comply with building, electrical, plumbing, mechanical, and fire codes adopted by the City of Bellevue.

  
  

  Bellevue ADU Regulations

  Bellevue ADU Reform FAQ