Spokane ADU Permit and Zoning Guide (2026)

Spokane ADU permit applications are processed by the City of Spokane’s Building Services Department, and the news for most homeowners is good. Washington’s HB 1337 fully applies to Spokane, Spokane’s compliance deadline of June 30, 2025 has already passed, and two ADUs per residential lot are now a protected right. Here’s what the local rules actually say.

What Spokane’s Local Zoning Actually Says

HB 1337 sets the floor. Spokane’s own code determines what’s permitted within those boundaries. Here’s how the city’s rules shake out for most residential lots.

Where ADUs Are Allowed

Both attached and detached ADUs are permitted in Spokane’s residential zones, from RA through RHD. That covers the large majority of single-family lots in the city.

How Many Per Lot

Under HB 1337, Spokane must allow two ADUs per lot. The city’s code is being updated to reflect this, but state law takes precedence. Two units in any combination of attached and detached is a protected right.

Maximum Size

Spokane caps detached ADUs at 1,000 square feet, which aligns with the state minimum floor. State law also prohibits the city from requiring your ADU to be smaller than 1,000 sq ft.

Setbacks

Detached ADUs in Spokane must observe the setback requirements of the underlying zone. A common reference point is 15 feet from rear property lines, but your specific zone may differ. Confirm your zone’s setback requirements before finalizing a site plan.

Parking

Studio and one-bedroom ADUs require no additional parking under Spokane’s current code. Two-bedroom units may require one space. State law also prohibits parking requirements for ADUs within half a mile of a major transit stop.

Short-Term Rentals and Owner-Occupancy

Spokane does not require owner-occupancy for standard long-term rental ADUs. However, if you plan to operate both an ADU and a short-term rental on the same lot, the city does require owner-occupancy for one of the units (SMC 17C.300.100). Check your city’s current short-term rental ordinance before counting on that income stream.

Permit Timeline and Fees

Spokane’s permit review for ADUs typically runs 50 to 75 days. Permit fees generally range from $2,000 to $3,500 depending on project scope. The city has also offered permit fee waivers for ADU projects in the past. Confirm the current fee schedule with City of Spokane Building Services.

One Thing Worth Knowing About Spokane’s Location

Spokane’s city limits and Spokane County’s unincorporated land are two different things. If your property address says Spokane but your parcel sits in unincorporated Spokane County, city zoning may not apply to you. Spokane County has its own ADU rules, which in some zones still require a Conditional Use Permit for detached ADUs.

Start by confirming your jurisdiction. Your zoning designation will tell you which set of rules applies.

What You Can Actually Build

Most Spokane homeowners pursuing a detached backyard ADU are looking at one of three configurations:

• A standalone backyard cottage, 600 to 1,000 square feet, with its own kitchen, bath, and entrance
• A detached garage or shop with a finished living unit above or beside it
• A smaller studio or one-bedroom unit for a family member or long-term tenant

Kit Culture’s current kit homes and our upcoming ADU-specific models are sized to fit within Spokane’s 1,000 square foot limit and arrive permit-ready with engineer-stamped drawings already included.

Also useful: Spokane Valley ADU Rules (2026)  •  Liberty Lake ADU Rules (2026)