ADU Pass
Spokane
Spokane County portion
Also in: No County
ADU Pass helps homeowners in Spokane, Spokane County, Washington navigate the permit paperwork for building an accessory dwelling unit. This area covers 9 ZIP codes.
Map
ADU details
ADU legality: allowed
Washington preempts most local ADU restrictions. Spokane permits ADUs by right in single-family zones per its zoning ordinance.
Cost scenarios
| Scenario | Sq ft | Permit | Build | Total |
|---|---|---|---|---|
| minimum | 150 | $2,900 | $60,300 | $63,200 |
| 600 | 600 | $2,900 | $241,200 | $244,100 |
| midpoint | 675 | $2,900 | $271,350 | $274,250 |
| maximum | 1,200 | $2,900 | $482,400 | $485,300 |
Fee breakdown (as of 2026-04)
Permitting process
- SMC 17C.300 zoning verification (~4d)
Confirm parcel is in a zone allowing ADU per SMC 17C.300.100/.110/.130: RA, R1, R2, RMF, RHD. Check Spokane River shoreline overlay, Aquifer Sensitive Area, and historic district overlays. Verify lot meets dimensional standards in the underlying zone. - Energy code worksheet preparation (~3d)
Complete the Washington State Energy Code (WSEC 2021) worksheet required for new ADUs - Spokane Permit Team will not begin plan review until the energy worksheet is uploaded. - Submit ADU building permit application via Accela Citizen Access (~1d)
Apply at aca.spokanepermits.org. Use the Accessory Dwelling Unit application packet. Upload site plan, floor plans, elevations, structural calcs, WSEC worksheet, Avista Utilities service plan, and STR registration affidavit if intending short-term rental use. - Intake and fee assessment (paid at submittal) (~2d)
Spokane Permit Team collects plan review fee, processing fee, and Washington State Building Code Council surcharge at submittal - not at issuance. STR-eligible ADUs require additional registration filing. - Concurrent plan review (planning, building, fire, integrated capital management) (~35d)
Planning reviews SMC 17C.300 conformance. Building reviews IRC 2021 with Washington amendments and Climate Zone 5B requirements. Spokane Fire reviews access. Integrated Capital Management reviews stormwater, water, and sewer. Typical 2 cycles for custom plans. - Permit issuance (~3d)
Final issuance of permit; remaining permit and impact fees collected. Permit valid 12 months from issuance with extension available. - Construction inspections through Accela
Footing, foundation, framing, mechanical/plumbing/electrical rough, insulation, drywall, final. Schedule via Accela or call 509-625-6300. - Certificate of occupancy (~5d)
Final inspection sign-off triggers CO; ADU eligible for occupancy and rental. STR use requires separate STR registration with City of Spokane.
Viability (permitted uses)
- Long-term rental: yes Long-term rental of ADU explicitly permitted; Washington owner-occupancy preemption (where applicable) makes ADU eligible for full landlord-tenant treatment.
- Short-term rental: with-restrictions STR rules vary by city. Spokane regulates STRs separately from ADU permitting; check local STR ordinance and HOA covenants.
- Office rental: with-restrictions Detached office rental requires home occupation permit or rezoning.
- Home office: yes Home occupation permitted with restrictions on signage and customer traffic.
- Studio / workshop: yes Personal artist studio is a permitted accessory use.
- Agriculture: with-restrictions Limited urban agriculture permitted in residential zones; livestock varies by district.
- Relative support: yes Family-occupancy ADU explicitly permitted in single-family zones.
Contacts
Staff: Residential Permit Process Counter (ADU and SFR intake), Avista Utilities - New Service (Electric and natural gas service for ADUs), Spokane Fire Department - Fire Prevention (Fire access review)
Utilities
- Water: Spokane Water Utility · 21d connect · $4,500
- Sewer: Spokane Sewer / Wastewater · 21d connect · $5,500
- Electric: Spokane Electric Utility · 14d connect · $1,800
- Gas: Spokane Gas Utility · 21d connect · $1,500
Property values & taxes
Construction timeline
Realistic total: best 7mo · typical 11mo · worst 17mo
Financing
State ADU loans:
Insurance impact
HOA prevalence & preemption
Washington enacted HOA preemption of ADU bans in Substitute House Bill 1337 (2023), which amended the Washington Uniform Common Interest Ownership Act and the Washington Horizontal Property Regimes Act to prohibit common-interest communities from banning ADUs on lots in GMA-planning jurisdictions. A homeowners' association may impose reasonable aesthetic or architectural standards, but may not categorically prohibit ADUs.
Technical envelope (climate & building code)
Climate & energy code
Building code
Amendments:
- Amendment
- Amendment
Legal history (timeline)
Current ordinance: Spokane Municipal Code Chapter 17C.300 - Accessory Dwelling Units (sections 17C.300.100 General Regulations, 17C.300.110 Criteria, 17C.300.130 Development Standards), adopted 2009-04-01, last amended 2024-06-17
- 2009-04-01 — Spokane original ADU ordinance (SMC Chapter 17C.300) (city-ordinance)
Initial adoption of Chapter 17C.300 establishing attached and detached ADU standards in residential zones.
Effect: Created the Spokane ADU framework with owner-occupancy requirement, parking minimum, and 800 sqft cap that governed for over a decade. - 2022-09-12 — Spokane ADU flexibility ordinance (Council action) (city-ordinance)
Spokane City Council added flexibility to ADU rules: removed owner-occupancy in most cases, raised size cap to 975 sqft, eliminated parking for studio/1BR ADUs, and reduced parking to one space for 2BR.
Effect: Permitting activity rose materially in the 12 months after adoption (per Spokane Journal of Business reporting). Short-term rental owner-occupancy lock-in retained. - 2023-05-08 — Washington EHB 1337 statewide ADU enabling act (state-law)
Required GMA-planning cities >= 2,500 population to allow two ADUs per single-family lot, drop parking minimum within 1/2 mile of major transit, and allow up to 1,000 sqft.
Effect: Spokane's 2022 reforms partially aligned with EHB 1337; subsequent 2024 ordinance raised the size cap to 1,000 sqft and introduced two-ADU-per-lot allowance. - 2024-04-15 — Spokane ADU Factsheet (TheZoneSpokane) (other)
Spokane Association of REALTORS' The Zone published an ADU factsheet summarizing post-reform rules.
Effect: Public-facing reference cementing the post-2024 design parameters; cited in homeowner education materials. - 2024-06-17 — Spokane Title 17 amendments aligning with EHB 1337 / HB 1110 (city-ordinance)
Title 17 amendments expanded ADU eligibility across RA-RHD zones, allowed two ADUs per lot in RA/R1/R2/RMF/RHD, and conformed to state floor on size and parking.
Effect: Codified the modern Chapter 17C.300 standards and established the AB-zone framework for middle-housing (HB 1110) compatibility.
Spokane County — county ADU rules and overlays
County permitting (unincorporated parcels)
Spokane County handles unincorporated permitting under its planning/development department.
Washington state — ADU law and programs
State ADU law
Washington preempts local ADU regulation in urban growth areas of cities and counties subject to the Growth Management Act through Engrossed Second Substitute House Bill 1337 (2023), codified principally at RCW 36.70A.680-.681. Cities and counties planning under the GMA must allow at least two ADUs per lot in urban growth areas, must not require owner-occupancy, must not impose minimum-lot-size or setback rules stricter than those for the primary residence, and must allow ADUs to be sold separately as condominiums. Related House Bill 1110 (2023), codified at RCW 36.70A.635, requires 'middle housing' (duplexes, triplexes, fourplexes) in most residential zones of large cities.
- RCW 36.70A.680 — Accessory dwelling units — Requirements for cities and counties planning under this chapter — Sets the minimum entitlement floor for ADUs in GMA-planning jurisdictions: at least two ADUs per lot in urban growth areas, no owner-occupancy requirement, no stricter setback or lot-coverage rules than for the primary residence, no parking requirements within a half-mile of major transit stops, and no prohibition on selling an ADU separately as a condominium.
- RCW 36.70A.681 — Accessory dwelling units — Design, size, and aesthetic standards — Caps what local governments may require in ADU design and size standards. Maximum ADU size must be at least 1,000 square feet in most zones. Street-facing facades and aesthetic review may not be used to categorically prohibit ADUs.
- RCW 36.70A.696 — Accessory dwelling units — Definitions — Statutory definitions of 'accessory dwelling unit,' 'attached accessory dwelling unit,' 'detached accessory dwelling unit,' 'owner,' and 'urban growth area' used by RCW 36.70A.680-.681.
- RCW 36.70A.635 — Middle housing — Cities planning under this chapter — HB 1110 (2023). Requires cities over specified population thresholds to allow duplexes, triplexes, fourplexes, townhouses, cottage housing, and stacked flats in most residential zones. Interacts with ADU law because ADUs and middle housing both contribute to the state's response to the GMA's housing element.
State HOA preemption
Washington enacted HOA preemption of ADU bans in Substitute House Bill 1337 (2023), which amended the Washington Uniform Common Interest Ownership Act and the Washington Horizontal Property Regimes Act to prohibit common-interest communities from banning ADUs on lots in GMA-planning jurisdictions. A homeowners' association may impose reasonable aesthetic or architectural standards, but may not categorically prohibit ADUs.
- RCW 64.38.057 — Homeowners' associations — Accessory dwelling units — Prohibits a homeowners' association governing a plat within a GMA-planning city or county from recording or enforcing a provision that prohibits the construction, use, or rental of an accessory dwelling unit on a lot. Reasonable design guidelines consistent with RCW 36.70A.681 remain enforceable.
State financing programs
The Washington State Housing Finance Commission (WSHFC) administers state-level housing finance programs. Washington does not currently operate an ADU-specific statewide grant or forgivable-loan program comparable to California's CalHFA ADU Grant, but several state programs can be used for ADU construction when program criteria are met.
State housing programs
Washington supports ADU implementation through Department of Commerce technical assistance and grant programs rather than through a single statewide pre-approved-plan catalog. The state provides model ADU code under the GMA, distributes GMA update grants to help jurisdictions comply with RCW 36.70A.680-.681, and has produced ADU guidance documents for local governments.
Federal (United States) — ADU-relevant rules and programs
Federal ADU law
The United States has no federal statute that directly regulates accessory dwelling unit entitlement or design. Land-use authority over ADUs resides with states and local governments under the traditional police power. Federal engagement is limited to financing (Fannie/Freddie/FHA/VA/USDA), flood insurance (FEMA/NFIP), and discretionary housing programs (HUD), which are recorded in sibling sections of this file.
Federal financing programs
Federal housing-finance agencies and GSEs set nationwide underwriting rules that govern whether an ADU can be financed, appraised, and counted toward mortgage qualifying income. The relevant actors are Fannie Mae, Freddie Mac, FHA (HUD), VA, and USDA Rural Development.
Federal tax credits
There is no ADU-specific federal tax credit. ADUs may incidentally qualify for existing federal energy-efficiency and clean-energy tax credits when the ADU construction includes qualifying measures.
Federal housing programs
HUD administers several discretionary programs that can fund ADU-related activity at the grantee's election, but none is an ADU-specific program.
ZIP Codes
- 99201
- 99203
- 99205
- 99207
- 99208
- 99217
- 99218
- 99223
- 99224
Post Office
- 1903 W Garland Ave, 99205
- 3120 S Grand Blvd, 99203
- 3910 N Crestline St, 99207
- 421 W Riverside Ave Ste 103, 99201
- 4401 N Freya St, 99217
- 5428 S Regal St, 99223
- 6801 W Flightline Blvd, 99224
- 904 W Riverside Ave, 99201
- 9857 N Nevada St, 99218