Walt Kane Construction, a Fall City, WA-based ADU contractor, builds custom accessory dwelling units including guest houses, rental units, in-law suites, and detached ADUs, focusing on durable materials, efficient layouts, and craftsmanship tailor... read more
Exceptional Home Builders is a Seattle ADU contractor with 20+ years of experience. They offer full-service ADU construction, design-build, permitting, interior design, and renovations for backyard cottages, garage conversions, and basement units.... read more
Deane Home Services builds ADUs in South King County, WA, including garage conversions, basement remodels, and detached backyard cottages. Licensed, bonded & insured. Serving Kent, Renton, Federal Way & more.
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Avio Homes is a Seattle-based ADU contractor specializing in detached ADUs, backyard cottages, and in-law suites. Serving Seattle, Tacoma, and Olympia, they handle design, permitting, and construction with local zoning expertise.
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Integrity Remodeling Inc is a Spokane, WA contractor specializing in ADU construction, garage conversions, and accessory dwelling units. Services include backyard cottages, basement apartments, in-law suites, and rentable ADUs for added property v... read more
When you choose Your Home Care Heroes, you’re choosing expertise focused on one goal: creating an exceptional building experience. Our clients consistently tell us they ‘love their home and wouldn’t change a thing,’ citing our clear commun... read more
DIGS is a trusted ADU builder serving King & Snohomish County, WA. They offer custom ADU/DADU design, permitting, construction, and site development, helping homeowners add rental income, property value, and flexible living space.
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Avead is an ADU contractor offering full-service accessory dwelling unit construction, including attached, detached, junior ADUs, garage conversions, and custom builds. With 20+ years of experience, transparent pricing, and a 5-year warranty.
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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 & per... read more
New Image Construction Management is a Washington State general contractor and building company based in Seattle, WA. With a primary focus of new home construction and renovation of residential and commercial properties.
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Giant Builders Seattle is a Kent, WA general contractor with 20+ years of experience offering ADU construction, garage conversions, kitchen & bathroom remodeling, room additions, roofing, deck building, and more.
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Northwest ADU builds custom detached ADUs, garage conversions & basement ADUs across Western Washington. Serving King, Pierce & Snohomish Counties with full-service ADU construction, build-ready plans & permit management.
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Hug Construction is an Inland Northwest contractor serving Spokane, Lincoln, Stevens, Pend Oreille, Bonner & Kootenai counties. Specializing in custom homes, remodeling, ADUs & commercial builds, they offer fixed bids, 2-year warranties &a... read more
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.
read moreWashington State has become one of the most ADU-friendly states in the nation, largely due to landmark legislation passed in recent years. In 2023, Washington enacted House Bill 1337, which significantly expanded ADU rights across the state. This law requires cities and counties to allow at least two ADUs per single-family lot, prohibits owner-occupancy requirements, and eliminates many restrictive parking mandates. For homeowners and ADU contractors in Washington, this legislation opened up tremendous opportunities to add accessory dwelling units to residential properties throughout the state.
While HB 1337 sets a statewide baseline, experienced ADU contractors in Washington State must still navigate local building codes and permitting processes that vary by jurisdiction. Cities like Seattle, Bellevue, Tacoma, and Spokane each maintain their own specific requirements regarding setbacks, height limits, and design standards. For example, Seattle allows ADUs up to 1,000 square feet for detached units and has its own streamlined permitting process. A knowledgeable Washington ADU contractor will be well-versed in these local nuances to ensure your project moves forward without costly delays.
Professional ADU builders in Washington are experienced in constructing a wide variety of accessory dwelling unit types to suit different property layouts and homeowner needs. Common ADU types include:
Choosing the right ADU contractor in Washington is critical to the success of your project. Washington State requires all general contractors to be licensed through the Washington State Department of Labor & Industries (L&I). Always verify your contractor holds a valid L&I license and carries proper liability insurance and workers' compensation coverage. Look for contractors with demonstrated experience in ADU construction specifically, as these projects involve unique challenges including utility connections, zoning compliance, and energy code requirements under the Washington State Energy Code (WSEC).
Investing in an ADU with a qualified Washington contractor offers significant long-term advantages. Homeowners can generate rental income to offset mortgage costs, provide housing for aging family members, or increase overall property value. With Washington's high housing demand, particularly in the Puget Sound region, ADUs represent a smart and increasingly accessible investment. Working with an experienced, licensed ADU contractor in Washington State ensures your project is completed safely, legally, and to the highest standards.