Typical Lot Size
6,000 – 9,000
sq ft
Max ADUs
2
per lot
Permit Type
Standard Building Permit (Seattle DCI)
Timeline
6 – 10 weeks
Median Home Price
$800K – $1.1M
Est. ADU Rent
$2,200 – $3,000/mo
Neighborhood Overview
West Seattle offers larger lots (6,000–9,000 sq ft) in the Admiral and Morgan Junction areas, RapidRide C Line service, and the lifestyle draw of Alki Beach. Spacious yards make it one of Seattle's best neighborhoods for detached backyard cottages.
West Seattle feels like its own coastal town, connected to the city by the West Seattle Bridge and the RapidRide C Line. Neighborhoods like Admiral, Alki, and Morgan Junction combine beach-town charm with larger, leafier lots than most of Seattle. Alki Beach draws residents and tenants alike with its waterfront promenade, while the Junction areas offer walkable commercial cores with restaurants and shops. Lots in the 6,000–9,000 sq ft range provide ample rear-yard space for detached ADUs, and the area's lifestyle premium supports strong rents. The peninsula's mix of Craftsman homes and mid-century houses, many with view potential, makes West Seattle a versatile and desirable ADU market.
West Seattle lots in Admiral and Morgan Junction commonly run 6,000–9,000 sq ft, larger than most Seattle neighborhoods. The generous rear yards make detached ADUs highly feasible, and some lots support a full 1,000 sq ft DADU.
ADU Construction Allowed
West Seattle qualifies for ADU construction under Seattle's ADU ordinance (SMC 23.44.041) and Washington's HB 1337.
- Detached ADUs (DADUs) allowed
- Attached ADUs allowed (basement, addition, above-garage)
- Up to 2 ADUs per lot
- Parking exempt (near transit)
Transit routes: RapidRide C Line, Metro Route 50, Metro Route 128, Metro Water Taxi
Why Build an ADU in West Seattle
- Larger lots (6,000–9,000 sq ft) in Admiral and Morgan Junction — ideal for detached cottages
- RapidRide C Line provides transit parking exemption for most lots
- Alki Beach lifestyle premium boosts rental demand and rates
- View lots add a significant rent premium for upper-level or rooftop-deck ADUs
- Up to 2 ADUs per lot under CB 119544; HB 1337 protects DADUs to 1,000 sq ft
Special Considerations
Shoreline review near Puget Sound
Lots within 200 ft of the shoreline trigger SMA review, adding 4–8 weeks and additional studies — relevant for Alki-area parcels.
Bluff and steep-slope overlays
Western West Seattle bluffs may require geotechnical assessment and engineered foundations, adding $15,000–$30,000.
Exceptional trees
Larger leafy lots frequently have trees over 24" DBH requiring a separate removal permit and arborist report.
Permit and impact fees
Budget $20,000–$50,000 in Seattle DCI fees on top of construction.
Learn more about ADU regulations: Review Seattle ADU laws, understand the permitting process, or see the complete cost breakdown for King County.
Explore ADU options: Compare detached ADUs, attached ADUs, garage conversions, and basement conversions. Not sure which? Read our DADU vs ADU comparison.
Planning resources: Financing options, rental income estimates, ROI analysis, and the complete building checklist.
Ready to get started? Our free feasibility study analyzes your specific parcel in 48 hours.
Frequently Asked Questions
Are West Seattle lots big enough for a detached ADU?
Yes — West Seattle has some of Seattle's larger residential lots, commonly 6,000–9,000 sq ft in Admiral and Morgan Junction. These generous rear yards make detached ADUs (DADUs) highly feasible, and many lots support a full 1,000 sq ft cottage. Seattle Municipal Code 23.44.041 governs DADUs, and HB 1337 protects detached units up to 1,000 sq ft from local size limits.
Does the RapidRide C Line exempt my West Seattle ADU from parking?
For most lots, yes. The RapidRide C Line is a frequent transit corridor, and properties within a half-mile of a frequent transit stop are exempt from ADU parking requirements. Lots farther from the C Line route may still need to verify exemption status, which we check in the feasibility study.
What about ADUs near Alki Beach and the shoreline?
Lots within 200 feet of the Puget Sound shoreline are subject to Shoreline Management Act (SMA) review, which adds 4–8 weeks and additional studies to the timeline. Most inland West Seattle lots are unaffected, but Alki-area parcels should plan for the extra review. We confirm shoreline status for your parcel.
How much can I rent a West Seattle ADU for?
West Seattle ADUs typically rent for $2,200–$3,000/mo, with view units and Alki-proximate properties commanding the top of the range. The beach-town lifestyle, walkable junctions, and water taxi access create steady demand.
