Attached ADU in Washington

Love Construction builds ADU & DADU units in Seattle & Puget Sound to Passive House standards. Attached ADUs cost $85K–$280K; DADUs $175K–$550K. Includes permitting, energy modeling & a 5-year warranty.

VDC Builders Inc specializes in ADU design & construction, including backyard cottages, in-law suites & rental units. Services cover flooring, kitchen & bathroom remodels, custom home building & cabinet refinishing.

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.

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.

Cruvers Contracting LLC builds ADUs in Snohomish, WA, tackling rural challenges like septic systems, slopes, and wooded lots. Serving areas including Lake Stevens, Monroe, and Everett with phased planning and durable, site-specific construction.

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.

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.

Tiny Cottage Builders NW offers ADU construction, garage conversions, basement finishing & home remodeling in Tri-Cities, WA. Led by Brandon Lott, every project is personally managed ensuring quality craftsmanship & clear communication.

Harjo Construction builds AADUs & DADUs in Seattle with 300+ projects since 2010. Costs range $275K–$650K, max 1,000 sq ft, 4–6 month build time. Seattle removed owner-occupancy rules, boosting ADU rental potential.

For more than 15 years, we’ve turned backyards into beautifully crafted living spaces. From permits to finishing touches, our team knows every step inside and out. Choose the classic charm of our Traditional Series, the clean lines of our Modern Series or the efficiency and flexibility of our Urban Series. Build with the crew that wrote the ADU playbook: RG ProBuilders.

Homez Remodel is a Seattle ADU builder specializing in DADUs, backyard cottages, garage conversions & basement ADUs. With 10+ years experience, they handle permits, design & construction across Seattle, Bellevue, Kirkland & more.

Gravity Builders LLC is a licensed ADU contractor and custom home builder in Renton, WA. Specializing in ADU/DADU construction, custom homes, outdoor living spaces, and concrete work, they deliver quality craftsmanship with transparency and integrity.

Accessory Dwelling Units (ADUs) add self-contained living space to existing properties. Rain Creek Construction serves Clark County homeowners with ADU builds, including garage conversions, basement apartments & detached units, backed by 10+ years of custom home experience.

Lakeside ADU & Home Planning, based in Lake Stevens, WA, is a full-service ADU builder serving the Puget Sound Region. They specialize in backyard cottages, mother-in-law suites, garage conversions, and new builds, managing design, permitting, and construction.