Spokane processes ADU permits ministerially under Spokane Municipal Code Chapter 17C.300, updated in 2024-2025 to comply with Washington HB 1337 (RCW 36.70A.680 et seq.). Two ADUs are allowed per lot in RA, R1, R2, RMF, and RHD zones. Applications go through the Permit Center at City Hall.
Spokane's ADU rules are in SMC Chapter 17C.300 (Accessory Dwelling Units), with sections 17C.300.010 (Purpose), 17C.300.100 (General Regulations), 17C.300.110 (Criteria), 17C.300.120 (Application Procedures), 17C.300.130 (Development Standards), and 17C.300.140 (ADU Expiration). Following Washington HB 1337 (Laws of 2023, ch. 332, codified at RCW 36.70A.680-.696), Spokane allows up to two ADUs per residential lot in the RA (Residential Agricultural), R1, R2, RMF (Residential Multifamily), and RHD (Residential High Density) zones. Review is ministerial - no public hearing, no neighborhood notification, no design review (RCW 36.70A.690 prohibits design standards more restrictive than those applied to the primary dwelling). Applications use the Spokane Permit Center / online portal with: site plan, floor plans, elevations, energy code (Washington State Energy Code) compliance forms, structural plans, and confirmation of sewer/water service. Maximum ADU size: 1,000 sq ft of floor area per unit under SMC 17C.300.110 (interior basement or attic conversions may exceed). Setbacks, height, and footprint are governed by SMC Table 17C.111.205-2. Parking requirements come from SMC Chapter 17C.230. Per RCW 36.70A.683, Spokane cannot require off-street parking for ADUs within one-half mile walking distance of a major transit stop.
Building an ADU without permits violates SMC Chapter 17F.040 (Building Code) and SMC 17C.300. Spokane Code Enforcement can issue stop-work orders, Notice and Order to Correct, and civil penalties under SMC 1.05 (typically starting around $100-$500 per violation). Unpermitted ADUs block sale, refinancing, and may trigger an order to remove the structure.
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