Spokane ADU rules
✓ Verified against code · August 20, 2026
Current rules under SMC 17C.300 (Accessory Dwelling Units), adopted by Ordinance C36696 (amended by Ord C36753), in effect since July 11, 2025. Spokane rewrote its ADU chapter in Ordinance C36696, effective July 11, 2025 — eleven days after the state's June 30 deadline — then amended the expiration and transfer provisions again in Ordinance C36753 (effective November 28, 2025). Read SMC 17C.300.140 carefully: it still speaks of "required" parking for ADUs, but the citywide minimum was already zero by then, so the condition it describes cannot arise today.
Common questions, answered from the code
How many ADUs can I build in Spokane?
Two per lot, in any combination of attached and detached — the code allows both types in the same zones and does not dictate a mix.
SMC 17C.300.100(A)–(B) · Permalink
Do I need parking for a Spokane ADU?
No. Spokane repealed its citywide off-street parking minimums in Ordinance C36629, effective March 2025, and the ADU chapter points back to that chapter for parking. One caveat worth knowing: SMC 17C.300.140 still uses the words "required parking" for ADUs. That language predates nothing and was left in place after the repeal, so the requirement it refers to is currently zero.
SMC 17C.230.110; SMC 17C.300.130 · Permalink
How tall can a detached Spokane ADU be?
25 ft, and the figure is the same in every residential zone — RA, R1, R2, RMF and RHD. That is one foot above the 24 ft floor HB 1337 requires.
Table 17C.111.205-2 · Permalink
Do I have to live on the property in Spokane?
Not normally. Owner-occupancy applies only if the lot has both an ADU and a short-term rental — then one unit must be the owner's permanent residence, occupied more than six months a year with no rental income from it. A hardship waiver of up to a year is available. Absent a short-term rental, there is no occupancy requirement.
SMC 17C.300.110 · Permalink
How close to the property line can a Spokane ADU sit?
Side setbacks are whatever applies to your primary structure. The rear setback is the interesting one: zero if your lot abuts an alley, 5 ft if it does not. Alley frontage is worth checking before you site a design.
Table 17C.111.205-2 · Permalink
The rules at a glance
| ADUs allowed per lot | Two per lot, attached and/or detached — both types are allowed in the same zones and the code sets no required mix.SMC 17C.300.100(A)–(B) |
| Maximum size | 1,000 sq ft for an attached ADU, excluding garage space, and the principal structure must itself be at least 1,000 sq ft (except for basement and attic conversions). A detached ADU is capped at 1,000 sq ft of floor area and a 1,200 sq ft building footprint.SMC 17C.300.110; Table 17C.111.205-2 |
| Detached ADU height | 25 ft, uniform across the RA, R1, R2, RMF and RHD zones.Table 17C.111.205-2, applied by SMC 17C.300.130 |
| Detached ADU setbacks | Side setbacks match the primary structure. Rear setback is zero where the lot abuts an alley, and 5 ft where it does not.Table 17C.111.205-2 |
| Off-street parking | None. Spokane repealed citywide off-street parking minimums, and the ADU chapter refers parking back to that chapter.SMC 17C.230.110; SMC 17C.300.130; Ord C36629Previously: Minimum off-street parking applied by zone — changed by Ord C36629 §13, effective Mar 6, 2025 |
| Owner-occupancy | Not required — with one exception. If a lot has both an ADU and a short-term rental, one of the units must be the owner's permanent residence (occupied more than six months a year, with no rental income from it); a hardship waiver of up to one year is available.SMC 17C.300.110 |
| Lot coverage / floor area | No floor-area ratio applies in residential zones. Lot and building coverage is calculated across all primary and accessory structures together, with no ADU-only cap beyond the 1,200 sq ft detached footprint limit.Table 17C.111.205-2 fn 5 |
| Permit path & timeline | Administrative: a building permit and certificate of occupancy through Building Services, with no discretionary land-use review. No published review timeline.SMC 17C.300.120 |
Worth knowing
- An ADU approval is not transferable except to a new owner who occupies the property (SMC 17C.300.140).
- An applicant may elect to treat a qualifying unit as either an ADU or a principal dwelling unit — a genuine choice, since the two carry different standards (SMC 17C.300.100).
- SMC 17C.300.140 still refers to maintaining "required" parking for both units. That language survived the citywide repeal of parking minimums, so the requirement it conditions on is currently zero. It reads like a conflict and is not one — but anyone reading that section alone will get the wrong answer.
- We could not confirm whether Spokane runs a pre-approved plan program or any ADU fee waiver: the city's planning pages returned errors on every path tried. That is an absence of evidence, not evidence of absence.
On our watchlist
Ordinance C36753 (effective November 28, 2025) amended the ADU expiration and transfer provisions; we have verified the current text but not the full scope of that amendment.
Whether Spokane offers pre-approved ADU plans or fee waivers is unverified — the city's planning pages were unreachable.
Primary sources
- SMC 17C.300 (Accessory Dwelling Units)
- SMC 17C.230 (Parking and Loading)
- Table 17C.111.205-2 (residential development standards)
Other Washington cities
Auburn · Bellevue · Bellingham · Bothell · Burien · Edmonds · Everett · Federal Way · Issaquah · Kent · Kirkland · Lynnwood · Olympia · Puyallup · Redmond · Renton · Sammamish · Seattle · Shoreline · Tacoma · Vancouver
Not legal advice. Every fact above cites the code section it comes from — check the cite, or ask your city’s planning department to confirm your specific lot. Spotted an error or a new ordinance? See about to reach us; corrections are logged in the changelog.