City of Spokane

Spokane Municipal Code

***Note: Many local criminal codes can now be located under Chapter 10.60 SMC while others are now cited under the Revised Code of Washington (RCW), which was incorporated into the municipal code in 2022. (See SMC 10.58.010). Code Enforcement, including Noise Control and Animal Regulations are located in Chapters 10.62 through 10.74.

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Title 17C
Chapter 17C.300
Section 17C.300.130
 

Title 17C Land Use Standards

Chapter 17C.300 Accessory Dwelling Units

Section 17C.300.130 Development Standards
  1. Development Standards – Requirements for All Accessory Dwelling Units.

All accessory dwelling units must meet the following:

    1.  
    2. Creation.
      1.  
      2. An accessory dwelling unit may only be created through the following methods:
      1.  
      2. Converting existing living area, attic, basement or garage.
      1.  
      2. Adding floor area.
      1.  
      2. Constructing a detached accessory dwelling unit on a site with an existing residential use.
      1.  
      2. Constructing a residential use with an attached or detached accessory dwelling unit.
      1.  
      2. In the R1, R2, RMF, or RHD zone, constructing an attached or detached accessory dwelling unit on a site with any existing or new principal structure (including non-residential uses or structures). Any structure shall comply with all applicable building, fire, and engineering standards
    1.  
    2. Number of Residents.

The total number of individuals that reside in all units on the site may not exceed any lawful limits on occupant load per square foot or generally applicable health and safety provisions as established by applicable building or fire code, as provided in RCW 35.21.682.

    1.  
    2. Parking.

Parking requirements are provided in Chapter 17C.230.

  1. Additional Development Standards for Detached ADUs.
  1. Setbacks.

Except for conversion of existing accessory structures, the accessory dwelling unit must be:

      1.  
      2. as specified for setbacks in Table 17C.111.205-2 for accessory dwelling units.
  1. Height.

The maximum height allowed for a detached accessory dwelling unit is provided in Table 17C.111.205-2.

  1. Bulk Limitation.
  1. The maximum building footprint for accessory dwelling units is provided in Table 17C.111.205-2.
  1. Attached ADUs shall be included in the maximum building footprint per primary building as provided in Table 17C.111.205-2.
  1. Conversion of Existing Detached Accessory Structures.
  1. Conversion of an existing detached accessory structure that is in a front building setback required by Table 17C.111.205-2 is allowed as provided. Conversion of an existing detached accessory structure that is in a rear or side building setback is allowed as provided by chapter 17C.111.235 SMC, Setbacks, and chapter 17C.111.240 SMC, Accessory Structures.
  1. If the accessory dwelling unit is proposed for an existing detached accessory structure that meets any of the standards of subsections (B)(2) and (3) of this section, alterations that will move the structure out of conformance with the standards that are met are not allowed.
  1. If the accessory dwelling unit is proposed as a conversion of an existing detached accessory structure or a portion of the building, and any floor area is added to the existing detached accessory structure to accommodate an ADU, then the entire structure must meet the underlying zoning development standards.
  1. Utilities and Addressing.

The ADU must utilize those municipal utilities and address established for the principal dwelling unit.

  1. Code Compliance.

The ADU must meet all technical code standards of this title including building, electrical, fire, and plumbing code requirements and permits.

Date Passed: Monday, June 2, 2025

Effective Date: Friday, July 11, 2025

ORD C36696 Section 3