Below you'll find real ADU projects we've completed in Seattle and King County — with actual costs, construction timelines, and project photos. Every ADU project is different: different lots, different goals, different budgets. These examples show the range of what's possible, from $300K rural cabins to $700K two-story cottages.
Each project includes the neighborhood, ADU type, square footage, and approximate cost range so you can compare to your own situation. For a deeper dive into ADU pricing, see our King County ADU cost breakdown. If you're ready to see what's buildable on your lot, start with a free feasibility report.
Beacon Hill Modern Cottage
Beacon Hill, Seattle
800 sq ft
2 bed / 1 bath
$490,000 – $560,000
Total cost
8 months
Total timeline
Beacon Hill
Neighborhood
A modern 800 sq ft backyard cottage with a clean shed roof, cedar and panel siding, and a bold orange entry door. Open floor plan with clerestory windows for natural light, mini-split HVAC, and drought-tolerant landscaping.
Project Highlights
- Link Light Rail adjacent — no parking pad required
- Clerestory windows for natural light
- Full kitchen with quartz counters
- Rents for approximately $2,600/month
Capitol Hill Backyard ADU
Capitol Hill, Seattle
850 sq ft
2 bed / 1 bath
$520,000 – $610,000
Total cost
9 months
Total timeline
Capitol Hill
Neighborhood
A compact modern ADU tucked behind an existing Capitol Hill home, with white horizontal siding, clerestory windows across the top, and a covered outdoor dining area.
Project Highlights
- Dedicated off-street parking for ADU tenant
- Modern clerestory window band
- Covered patio extends living space
- Complements existing primary home style
Ballard Garage-Over-Living ADU
Ballard, Seattle
1,000 sq ft
2 bed / 1 bath
$580,000 – $700,000
Total cost
10 months
Total timeline
Ballard
Neighborhood
A two-story detached ADU with a single-car garage on the ground floor and a 1,000 sq ft living unit above. Cedar accent siding, standing seam metal roof, and an exterior staircase.
Project Highlights
- Garage below eliminates separate parking requirement
- Cedar and HardiPanel mixed exterior
- Takes advantage of natural slope
- Rents for approximately $3,100/month
Columbia City Classic Cottage
Columbia City, Seattle
750 sq ft
2 bed / 1 bath
$460,000 – $530,000
Total cost
8 months
Total timeline
Columbia City
Neighborhood
A charming two-story cottage designed to match the historic character of the Columbia City neighborhood. Traditional blue lap siding with white trim and a covered entry porch.
Project Highlights
- Neighborhood-compatible craftsman design
- Covered entry porch with timber details
- Second-floor balcony with glass railing
- Skylight for added upper-floor light
Fremont Modern Farmhouse ADU
Fremont, Seattle
900 sq ft
2 bed / 1 bath
$560,000 – $660,000
Total cost
9 months
Total timeline
Fremont
Neighborhood
A striking modern farmhouse-style ADU clad entirely in corrugated metal with a clean gable profile. Large ground-floor windows and a generous upper-floor dormer.
Project Highlights
- Corrugated metal cladding — low maintenance
- Open-plan ground floor with wall of windows
- Upper-floor loft bedroom with dormer
- Energy-efficient envelope with superior insulation
Northgate Cedar Studio
Northgate, Seattle
600 sq ft
1 bed / 1 bath
$460,000 – $510,000
Total cost
6 months
Total timeline
Northgate
Neighborhood
A single-story 600 sq ft studio cottage with western red cedar siding, oversized picture windows, and exposed timber rafters. Designed as an aging-in-place unit with zero-step entry.
Project Highlights
- Zero-step entry for ADA accessibility
- Western red cedar siding throughout
- Oversized windows for mountain views
- Near Link Light Rail — parking exemption applied
Vashon Island Woodland Retreat
Vashon Island, King County
400 sq ft
1 bed / 1 bath
$300,000 – $380,000
Total cost
6 months
Total timeline
Vashon Island
Neighborhood
A handcrafted 400 sq ft cedar cabin on a 5-acre rural King County parcel. All-cedar construction with custom curved window details, a wood-burning stove, and a covered front porch.
Project Highlights
- All-cedar artisan construction
- Custom curved window details
- Wood-burning stove for primary heat
- Administrative Use Permit — rural pathway
More From Our Portfolio
Why Our Portfolio Matters
Most ADU builders in Washington State show renderings. We show finished projects — with real numbers attached. That transparency matters because ADU construction costs vary widely depending on lot conditions, design complexity, and finish level. The projects above represent the honest range of what ADUs cost to build in Seattle and King County today.
Our portfolio also demonstrates range. We've built modern shed-roof cottages in Beacon Hill, craftsman-style units in Columbia City, above-garage ADUs in Ballard, and rural cabins on Vashon Island. That variety means we can match your ADU design to the character of your neighborhood — not force a generic plan onto your lot.
Every project in our portfolio was built with sustainable construction practices as standard, and every one was permitted through either the City of Seattle or King County permitting process. We handle design, permitting, and construction as a single integrated service.
By the Numbers
50+
ADU permits processed
100+
ADUs built
4–10
Month avg. timeline
15+
Seattle neighborhoods
Ready to Start Your Own ADU Project?
Every project in our portfolio started the same way — with a free feasibility study. We'll assess your property's zoning, buildable area, and estimated costs within 48 hours.
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