Attached ADU near Mukilteo, WA

Seattle's 2019 ADU law changes made it easier to build accessory dwelling units on single-family lots. DADUs can't exceed 50% of the main home's size. No parking required. New detached ADUs start around $350,000.

Backyard ADU is a full-service ADU contractor managing every stage of accessory dwelling unit builds, including feasibility, permits, site surveys, foundations, construction, utility connections, and condo legal services.

Wise Choice Construction offers expert home additions & ADU builds in Seattle, WA. From detached ADUs and granny flats to in-law suites, they handle permits, zoning, and seamless integration—boosting property value and livable space.

Twin Brothers Group is a licensed framing contractor in Washington State specializing in ADU, DADU, garage conversions, and home additions across King and Snohomish County, serving Seattle-area GCs and owner-builders.

Puget Sound ADU Builders is a leader in ADU construction in western Washington state, excelling in design, construction, finishing, and permitting ADUs, DADUs, backyard cabins, garage conversions, duplexes, town homes, and multi-unit projects.

NorthLight Custom Builders offers ADU construction in King & Snohomish County. Services include attached & detached units for rental income, family living, or home offices. Structured process from consultation to one-year warranty follow-up.

Neil Kelly Washington offers ADU design and build services in the Northwest, including detached ADUs, garage conversions, and attached units. Their team navigates local permits, balances design with functionality, and helps homeowners add value through custom accessory dwelling units.

Raincap Construction, a Seattle-based family-owned contractor, specializes in ADU and DADU construction. They build backyard cottages, in-law suites, and garage conversions, helping homeowners add living space, rental income, and property value.

Red's Construction & Renovation serves Federal Way & South King County, WA, specializing in ADU construction including detached, attached, garage conversions & basement units. Costs range from $50K–$300K+. Licensed, insured, transparent pricing.

Seattle ADUs offer rental income & flexible living. Coates Design Architects guides homeowners through detached, attached, garage & basement conversions. Costs range $200K–$350K+, with 7–11 month timelines. Sustainable design & permit-ready plans included.

HiLine Homes is an experienced ADU builder in Idaho with nearly 30 years in custom home construction. They offer attached and detached ADU designs for rental income, multigenerational living, or home offices, with financing options available.

H26 Builders is a Seattle ADU contractor offering attached ADUs, detached ADUs, and garage conversions. Services include design consultation, permitting support, and project management to help homeowners add functional living or rental space.

Seattle's trusted DADU & ADU builder offers custom builds, ADU conversions, and prefab cabins. Transparent pricing, expert guidance, and hands-on construction help homeowners add lasting value with backyard cottages and granny flats.