Cornerstone Builders LLC is a Sequim-based ADU builder serving Washington's North Olympic Peninsula for 40+ years. This certified design-build firm manages all phases—design, permitting, and construction—offering transparent, process-driven ADU solutions.
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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.
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Heartwood Builders is a Seattle ADU contractor specializing in backyard cottages, basement ADUs, and mother-in-law suites. They handle permitting, use sustainable materials, and help homeowners add rental income or family housing.
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Seattle Remodeling LLC specializes in ADU construction in Seattle, offering mother-in-law suites, backyard cottages, garage conversions, and granny flats. They help homeowners add value, rental income, and flexible living space.
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True Built Home builds custom ADUs in Washington & Oregon, offering 14 floor plans from 495–1,199 sq ft, priced from $119,900. Plans include granny flats, in-law suites & backyard cottages with transparent pricing and customizable designs.
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BB Builders Pro specializes in ADU construction, garage conversions, home additions, and detached backyard cottages. Services include custom design, permitting, zoning compliance, and renovations—ideal for rental income or family housing.
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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.
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Greenpod Design builds custom DADUs in Washington using SIP construction and sustainable materials. They handle permits, ADA-compliant design, and energy-efficient builds. WA law allows up to two ADUs per lot, up to 1,000 sq ft.
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Huskies Construction in Renton specializes in home additions, ADUs, and DADUs. Services include garage conversions, granny flats, in-law suites, backyard cottages, and room additions, helping homeowners expand living space or generate rental income.
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Tacoma DADU Builders is a premier detached ADU builder serving Tacoma and Puget Sound. With 40+ years of experience, they offer turnkey ADU construction—design, permitting, and build—for investors, homeowners, and first-time buyers.
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Armada Design & Build Inc., Bellevue, WA, offers full-service residential design-build since 2011. Specializing in remodels, home additions, and custom builds across Puget Sound, they deliver turnkey solutions with in-house design and quality craftsmanship.
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Northwest ADU is a full-service ADU contractor in Western Washington specializing in detached ADUs, garage conversions, and basement conversions. Serving Pierce, King, and Snohomish Counties, projects range from $180K–$350K+, taking 6–10 months.
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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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Seattle ADU is a Seattle-based contractor specializing in accessory dwelling units, including detached ADUs, garage conversions, attached ADUs, and JADUs. They manage design, permitting, and construction for homeowners seeking additional living space.
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Evola Builds LLC, led by Michael and Amber Evola, offers residential renovation and construction services including bathroom remodels, ADU work, garage conversions, and structural modifications, collaborating closely with architects and homeowners.
read moreSeattle, Washington has become one of the most ADU-friendly cities in the United States. In 2019, the city passed landmark legislation that significantly relaxed restrictions on Accessory Dwelling Units (ADUs), allowing homeowners to build both an attached ADU and a detached ADU (DADU) on the same property simultaneously. This progressive policy shift has created a booming demand for experienced ADU contractors in Seattle, making it essential to find professionals who understand the city's unique regulatory landscape.
Hiring a knowledgeable Seattle ADU contractor means working with someone who is well-versed in the city's specific building codes and zoning requirements. Seattle's Department of Construction and Inspections (SDCI) oversees all ADU permits, and navigating this process requires expertise. Some critical regulations include:
Finding the right ADU builder in Seattle is critical to the success of your project. The city's hilly terrain, frequent rainfall, and older housing stock present unique construction challenges. A qualified contractor should have experience working with Seattle's soil conditions, understanding of stormwater management requirements, and familiarity with the city's energy code, which aligns with Washington State's strict energy efficiency standards. Always verify that your contractor holds a valid Washington State contractor's license and carries proper liability insurance.
The permitting process for ADUs in Seattle can be complex and time-consuming. Working with an experienced Seattle ADU contractor who understands the SDCI's online permitting portal and plan review process can save significant time and money. The typical steps include:
With Seattle's consistently high rental demand and competitive housing market, building an ADU is a smart financial investment. Seattle ADU contractors report strong interest from homeowners looking to generate rental income, house family members, or increase overall property value. Whether you're considering a backyard cottage, a garage conversion, or a basement ADU, partnering with a skilled and licensed contractor who knows Seattle's building environment is the key to a successful and compliant project.