DADU Regulations | City of Tacoma

• On legally established lots in residential zones permitting single-family dwellings (and some mixed zones), the city allows up to two ADUs per lot (either attached or detached) as an accessory use to a primary residence.

  
  

• Maximum size: The living area of an ADU (excluding non-living areas) is limited to 1,000 square feet in most cases.

  
  

• Setbacks & Location (for detached ADUs):

  • Rear yard placement, minimum 5-foot side setback; along an alley no rear setback required.

    
    

• Height: Detached ADUs must not exceed the height of the main house; a guideline: up to 18 ft to midpoint of peaked roof, or up to 20 ft if certain conditions (e.g., parking or environmental certification) are met.

  
  

• Parking: No additional off-street parking is required for an ADU. If parking is added, it must be accessed from the rear portion of the lot and may not remove the required parking for the main dwelling.

  
  

• Open Space / Yard: The overall site must maintain at least 10% of the lot as usable yard space.

  
  

• Design & Architecture: ADUs must include full facilities (living, cooking, sanitation, sleeping) and must visually complement the main dwelling in materials and character, especially in detached units.

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