On legally established lots in residential zones permitting single-family dwellings (and some mixed zones), the city allows up to two ADUs  per lot (either attached or detached) as an accessory use to a primary residence. Maximum size:  The living area of an ADU (excluding non-living areas) is limited to 1,000 square feet  in most cases. Setbacks & Location (for detached ADUs): Rear yard placement, minimum 5-foot side setback; along an alley no rear setback required. Height:

King County ADU / DADU Regulations В незанятой части King County ADU разрешены на участках с существующим жилым домом, согласно King County Code Title 21A (KCC 21A.08.030 B.7). Максимальный размер: ADU не должна превышать 1 000 кв. футов (≈ 93 м²) отапливаемой площади  и 1 000 кв. футов неотапливаемой площади . Если ADU полностью размещена в подвале или чердаке существующего дома — это ограничение может не применяться. В урбан-зоне возможно увеличение отапливаемой площади до

The maximum floor area  for an ADU (attached or detached) is 1,000 square feet . Up to two ADUs  may be allowed on a single lot in certain residential zones under the city’s Growth Management Act (GMA) authority. ADU projects must meet engineering and stormwater requirements , especially when located in combined sewer areas. In 2023, Ordinance 3963-23  simplified Everett’s ADU regulations to improve housing flexibility and affordability, streamline review, and relax setback a

Maximum size:  An ADU may not exceed 1,200 sq ft  or 40 percent of the combined gross floor area  of the principal dwelling plus the ADU (excluding garage space) — whichever is greater. Parking requirements: No parking is required if the ADU is under 1,000 sq ft  or located within ½ mile of frequent transit service . For ADUs 1,000 sq ft or larger , one parking space is required (unless the transit exemption applies). For ADUs over 2,000 sq ft , one space is required for lots

In urban zones (UGA – Urban Growth Area) , the maximum size for an ADU is 1,000 square feet  of floor area. In rural zones (outside the UGA) , the maximum size increases to 1,250 square feet . Only one ADU is permitted per lot of record  (either attached or detached). On lots smaller than 1 acre , detached accessory structures (including garages and workshops) cannot exceed 2,000 sq ft , excluding the ADU itself. Pierce County is currently reviewing housing code updates  to e

The prices for the Architectural Set are fixed and valid until May 2026. Type of Project Architectural Design Structural Engineering Civil (Drainage Report) (if required) Septic Design (if required) Additional Reports (if required) DADU < 1000 sq ft $3000 - $4,000 ~$3,800 ~$2,800 ~$3,500 Geotech / Arborist / Topo Survey — case-by-case DADU < 1000 sq ft + Garage $3000 - $4,500 ~$3,800 ~$2,800 ~$3,500 Geotech / Arborist / Topo Survey — case-by-case DADU 1000 sq ft $4,000 ~$3,80

In unincorporated King County , accessory dwelling units (ADUs) are allowed on lots that contain an existing dwelling, as defined in King County Code Title 21A (KCC 21A.08.030 B.7) . Maximum Size: The heated floor area of an ADU may not exceed 1,000 square feet , plus up to 1,000 square feet of unheated area  (such as garage, storage, or unfinished basement). If the ADU is entirely located within an existing basement or attic, the size limit may not apply. In some urban zones

In Snohomish County urban zones (see SCC 30.22.100) accessory dwelling units are permitted on lots with a legally-established principal unit. Number of units per lot (urban zones): If the principal unit is a single-family dwelling or duplex: up to two  ADUs are allowed on the lot in the following configurations: One attached + one detached ADU, or Two attached ADUs, or Two detached ADUs (in one or two structures). If the principal unit is a single-family attached dwelling: on

In Seattle, both attached (AADU) and detached (DADU) accessory dwelling units are permitted on lots where single-family dwellings are allowed. Seattle+2Seattle+2 Number of units per lot:  Up to two ADUs  (in addition to the primary dwelling) are allowed on one lot. These can be any combination of attached and detached units. Seattle+2Building Connections+2 Maximum size: The gross floor area of an ADU may not exceed 1,000 square feet . For a DADU in many zones the same 1,000 s