ADU Pass
Bellevue
King County portion
Also in: No County
ADU Pass helps homeowners in Bellevue, King County, Washington navigate the permit paperwork for building an accessory dwelling unit. This area covers 6 ZIP codes.
Map
ADU details
ADU legality: allowed
Washington preempts most local ADU restrictions. Bellevue permits ADUs by right in single-family zones per its zoning ordinance.
Cost scenarios
| Scenario | Sq ft | Permit | Build | Total |
|---|---|---|---|---|
| minimum | 150 | $2,900 | $79,350 | $82,250 |
| 600 | 600 | $2,900 | $317,400 | $320,300 |
| midpoint | 675 | $2,900 | $357,075 | $359,975 |
| maximum | 1,200 | $2,900 | $634,800 | $637,700 |
Fee breakdown (as of 2026-04)
Permitting process
- Pre-application via Service First (~5d)
Call or email Service First (425-452-6800 / servicefirst@bellevuewa.gov) to confirm zoning (R-1 through R-30, Mixed Use, Downtown), critical area constraints (steep slopes east of I-405, Lake Sammamish/Lake Washington shoreline, Coal Creek/Kelsey Creek streams), and confirm whether the property triggers Bellevue's Single-Family Land Use district design review. - MyBuildingPermit online application (~1d)
Submit through MyBuildingPermit.com (eGov Alliance shared portal used by 18 Eastside cities). Bellevue accepts only digital submittals - paper applications are not accepted. Upload PDF set: site plan with shoreline buffer if applicable, foundation, floor, elevations, energy code (WSEC 2021 Bellevue amendments), structural calcs, geotech if on regulated slope. - Intake screening (3-business-day target) (~5d)
Bellevue Development Services screens for completeness within 3 business days. Common holds: missing geotech on >15% slope, missing tree retention plan, missing critical-areas study. - Concurrent multi-discipline review (~28d)
Building, land use/zoning, fire (Bellevue Fire Department reviews onsite hydrant flow), clearing/grading, transportation (impact fee calc), and utilities review concurrently via MyBuildingPermit. Bellevue runs a 4-week first-cycle target on residential ADU. - Address corrections and resubmit (~14d)
Typical 1-2 cycles for ADU; Bellevue responds within 10 business days on resubmittal. Conversion AADUs in older homes often trigger separate energy-code-compliance items (existing-house thermal envelope upgrade). - Permit issuance and fees through MyBuildingPermit (~2d)
Pay building, plan review, fire, transportation impact (suspended for ADUs <1000 sqft per RCW 36.70A.681), school impact (Bellevue and Lake Washington School Districts - waived for ADUs), park impact, and Bellevue Utilities SDC. Permit downloads instantly from MyBuildingPermit. - Construction inspections through MyBuildingPermit
Inspections requested at MyBuildingPermit. Bellevue inspects: setback verification (planning), erosion control, footing, foundation/wall, framing/shear, plumbing rough, mechanical rough, insulation, drywall, gas test, final building. - Final and Certificate of Occupancy (~5d)
Final building inspection issues CO via MyBuildingPermit. ADU registration NO LONGER REQUIRED (eliminated by Ordinance 6746); ADU is occupiable on CO without separate registration filing. King County Assessor parcel update follows.
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. Bellevue 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: Service First (general intake and triage) (First-stop permitting concierge) servicefirst@bellevuewa.gov, Bellevue Fire Department - Plans Review (Fire flow / hydrant / sprinkler review), Bellevue Utilities (water, sewer, stormwater) (Utility System Development Charge), Bellevue Land Use Planning Counter (Zoning, critical areas, design review)
Utilities
- Water: Bellevue Water Utility · 21d connect · $4,500
- Sewer: Bellevue Sewer / Wastewater · 21d connect · $5,500
- Electric: Bellevue Electric Utility · 14d connect · $1,800
- Gas: Bellevue 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: Bellevue Land Use Code 20.20.580 - Accessory Dwelling Units (as amended by Ord. 6746 and 2025 conformance amendments), adopted 1993-01-01, last amended 2025-06-30
- 1993-01-01 — Bellevue Land Use Code (LUC) 20.20.580 - original AADU provisions (city-ordinance)
Bellevue first authorized attached accessory dwelling units (AADUs) in single-family zones via LUC 20.20.580 in 1993, subject to owner-occupancy, registration, separate-ownership prohibition, and parking minimums.
Effect: Permitted AADUs (basement/attic/attached) but kept barriers in place: owner had to live on site, ADU required registration with planning department, ADU could not be conveyed separately, and an additional off-street parking space was required. - 2023-01-17 — ADU Reform Land Use Code Amendment (LUCA) initiation - Council Resolution (city-ordinance)
Council initiated Phase 1 of Middle-Scale Housing action targeting ADU barriers: owner-occupancy, design controls, separate-ownership prohibition, size limits, registration/notice procedures, and parking minimums.
Effect: Began the formal LUCA process that would culminate in Ordinance 6746. - 2023-05-08 — Washington EHB 1337 (RCW 36.70A.681) - statewide ADU enabling (state-law)
Statewide preemption requiring two ADUs per single-family lot in UGAs, banning owner-occupancy and prohibiting parking minimums within 1/2 mile of major transit.
Effect: Imposed June 30, 2025 compliance deadline on Bellevue. - 2024-04-01 — Bellevue Ordinance 6746 - ADU Reform LUCA adoption (city-ordinance)
Adopted ADU Reform LUCA: removed owner-occupancy, eliminated registration and noticing, raised AADU size cap, allowed two ADUs per lot, removed parking minimums in transit overlay, allowed condominium-style separate ownership.
Effect: Made Bellevue one of Washington's most permissive ADU programs - it now allows separate ownership of AADUs (RCW 64.90 condominium pathway) which most cities still prohibit. - 2025-06-30 — Bellevue HB 1110/1337 final compliance amendments (city-ordinance)
Final cleanup amendments to LUC 20.20.580 and adjacent middle-housing sections to reach state HB 1110 (middle housing) and HB 1337 (ADU) compliance ahead of June 30, 2025 deadline.
Effect: Formally aligned all ADU provisions with state-mandated minimums; activated 'no registration required' policy citywide.
King County — county ADU rules and overlays
County permitting (unincorporated parcels)
King 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
- 98004
- 98005
- 98006
- 98007
- 98008
- 98039
Post Office
- 1171 Bellevue Way NE, 98004
- 12400 SE 38th St, 98006
- 13400 SE 30th St, 98005
- 15731 NE 8th St, 98008