11 vetted ADU and DADU builders serving Seattle and the surrounding Puget Sound area. Compare ratings, price ranges, and specialties, then request free quotes.
Seattle is the largest ADU market in the Puget Sound region, and the city has actively encouraged backyard cottages through its pre-approved DADU plan program and permit reforms. Building permits are issued by the Seattle Department of Construction & Inspections (SDCI), and under Washington's HB 1337 most residential lots can now add an accessory dwelling unit with no owner-occupancy requirement. Whether you're converting a basement or building a detached backyard cottage, the builders below focus on Seattle's permitting process and lot conditions.
Premier Seattle ADU and DADU contractor offering custom builds, prefab plans pre-approved by the City of Seattle, and full-service design and engineering.
Award-winning Seattle remodeling contractor specializing in ADUs, backyard cottages, kitchen remodels, and home additions. Certified Sustainable Building advisor.
Licensed ADU specialists in Seattle offering end-to-end services including consultation, design and planning, permitting assistance, and construction. 3-month turnaround on DADU turnkey projects.
Specializes in ADU and DADU construction in Seattle and surrounding areas. Custom designs, transparent pricing, sustainable building practices.
Premier DADU construction contractor in Seattle. Handles all permitting needs. Innovative design solutions and expert construction team.
Custom ADU specialists serving Seattle, Bellevue, and greater Puget Sound. Full-service from design to permitting to construction. Free estimates available.
Full home remodeling contractor with ADU specialization. Covers wide service area across Greater Seattle and Eastside.
Established 2007. Experienced in custom remodeling and ADU/DADU construction. 6-9 month average timeline. Specializes in all architectural styles.
Premier ADU builder serving Seattle area and beyond. In-house design team. Sustainable design options. Full permitting and construction management.
Exclusive custom contractor for all Urban Cottage ADU/DADU projects. Full permit-to-build service. Expert guidance on ADU regulations.
Comprehensive DADU service integrating financing, building, and management. Offers PDF booklet resource on ADU planning. Award-winning quality.
No. Washington's HB 1337 eliminated owner-occupancy requirements statewide, so Seattle homeowners can build a detached DADU or an attached ADU and rent out either the main house or the accessory unit. Seattle also offers pre-approved DADU plans that can shorten the permitting timeline.
ADU and DADU permits in Seattle are issued by the Seattle Department of Construction & Inspections (SDCI). Most projects require a construction permit, and detached units may also need site and utility review depending on lot conditions.
Costs vary widely by size, type (attached vs. detached), and site conditions such as sewer connections and slope. See our Washington ADU cost guide for current ranges, then request free quotes from the Seattle builders above to compare bids.