Well-Reviewed ADU Builders in Seattle & Washington State

Washington changed its ADU rules in 2023, when state law required cities to allow up to two accessory dwelling units on most residential lots. Seattle and Tacoma went further, releasing pre-approved DADU plans that can shave months off the permit timeline.

The result is a deep bench of ADU builders across Washington state, from specialists who've made backyard housing their entire business to established remodelers who added DADUs to their service line. Below, 24 companies worth knowing, organized by region. A few have been doing this since before the policy tailwind made it a category. Others were founded the year the rules changed.

Seattle and King County ADU builders

AmyWorks

Amy Ecklund founded AmyWorks in 2010 with a stated focus on serving homeowners, particularly women and the LGBTQIA+ community, who'd had bad experiences in the traditional remodeling industry. The company is woman-owned and builds both ADUs and DADUs alongside kitchens, baths, basements, and garage remodels. Ecklund holds an NAHB Certified Graduate Remodeler designation and a Washington State Certified Builder credential, and was named the Master Builders Association Remodelers Council Builder Member of the Year in 2023. The team operates out of the SoDo office and runs DIY home repair workshops on the side. Communication and team culture get more attention here than at most contractors, which lands as warm for some clients and as more involvement than expected for others. 

Address: 217 S Orcas St, Seattle, WA 98108, United States 

Facebook: https://www.facebook.com/AmyWorksSeattle/

Backyard ADU

Backyard ADU runs a turnkey model that bundles surveys, utility connections, foundation work, and full construction under one contract. Named ADU models are published online so clients can browse before booking a consultation, which simplifies the first conversation. The trade-off is flexibility: the catalog is the starting point, so clients with very specific design goals may want a more custom-leaning firm. 

Facebook: https://www.facebook.com/thebackyardadu

Ballard Backyard Cottages

Ballard Backyard Cottages has built nearly 20 DADUs across Seattle since 2020, in neighborhoods including Ballard, Beacon Hill, South Park, Northgate, and West Seattle. The firm works in three modes: custom designs, prefab kit homes, and Seattle's pre-approved plans, with a published case study of a 450 square foot South Park DADU that came in around $257,000 all-in. Call them if you're still deciding between custom and pre-approved and want real numbers from both options.

Facebook: https://www.facebook.com/seattleminihomes/

CTA Design Builders

CTA Design Builders splits its calendar between ADUs, DADUs, custom homes, and major remodels out of a single Seattle design-build office. The website goes deeper than most into Seattle's specific DADU regulations, which is a good sign for clients who don't want to learn the code from scratch. The projects gallery shows multiple ADU builds with full case-study detail. Their work makes sense when the ADU sits inside a larger renovation, or when you want full custom-home capability behind the smaller build. 

Address: 1101 N. Northlake Way, Suite 201 Seattle, WA, 98103 

Facebook: https://www.facebook.com/CTADESIGNBUILDERS

Haas Development & Construction

DADU projects sit alongside the kitchen and bath work that anchors most of Haas Development & Construction's calendar. The Seattle remodeling and design-build company offers pre-approved DADU plans plus custom builds, with a Seattle DADU case study published on the projects page. They're licensed and bonded, with depth in larger remodels that dedicated ADU shops can't match. Plan on a feasibility check before any design work begins. 

Facebook: https://www.facebook.com/haasdevelopmentandconstruction

Model Remodel

Environmentally-focused positioning has been part of Model Remodel's brand for years, baked into how the Seattle design-build firm describes its work. Multiple backyard cottage projects sit on the company's project list, including a Ballard build featured in detail on the site. Green building specifications come up in the early design conversation, not as an upcharge later. 

Facebook: https://www.facebook.com/modelremodel

Address: 1111 W Nickerson St, Seattle, WA 98119 

Near East Sheds

Custom sheds and outbuildings are the bulk of what Near East Sheds builds, with permitted ADU projects taken on across King, Pierce, and Snohomish counties. On-site construction and a 2-year warranty distinguish them from prefab-only operators in the same category. They're a different conversation than dedicated ADU builders: this is a sheds-and-garages team that builds ADUs, not an ADU team that grew up building small houses. 

Address: 2361 S 200th St. Seattle, WA 98198 

Facebook: https://www.facebook.com/people/Near-East-Storage-Sheds/

NW ADU Builders

Fixed-price contracts are NW ADU Builders' clearest hook, a structure that protects clients from the cost creep that turns budget renovations into financial events. The firm has completed more than 40 accessory dwelling units across Seattle, Tacoma, and the rest of the Puget Sound region. Permits, design, and construction all sit with the same team, with no separate design firm to coordinate. The company is licensed for ADU and DADU work specifically. Pick them when budget certainty matters more than catalog variety. 

Puget Sound ADU Builders

Tanya Mills leads Puget Sound ADU Builders, a women-owned family shop with general contractor Morgan running construction and roughly 30 years of combined experience between the leadership. The company itself is relatively new, even though the people running it aren't. Services include detached and attached ADUs, garage conversions, and condoization, the legal process of declaring an ADU a separate condominium so it can be sold independently of the main home. They build from Mill Creek and Edmonds in the north down through Seattle, Kirkland, and Renton. ADA certification means accessibility planning is part of the standard process, not a line item. Tanya runs the front of every project from first call through final walk-through, which suits clients who want owner-level involvement and may feel like overkill to those who don't.

Address: 2226 Eastlake Ave E Seattle, WA 98102

Facebook: https://www.facebook.com/pugetsoundadubuilders

Seattle ADU Builders

Seattle ADU Builders limits its work to inside the city, handling permitting and construction for detached and attached units. Garage conversions make up a sizable share of their work, which can be a cost-effective ADU path on lots that already have a structure to convert. They don't take on projects outside Seattle, which is a real constraint for suburban buyers but an advantage if you want a builder who lives the local code. 

Address: 4138 Baker Ave NW, Seattle, WA 98107 

Facebook: https://www.facebook.com/seattleadubuilders

Seattle ADU Solutions

Seattle ADU Solutions covers Bellevue, Everett, Tacoma, and Seattle, which is a wide service area for a single Puget Sound contractor. Engineering, design, and permitting all sit in-house alongside construction, so clients aren't coordinating between four separate vendors. The team builds both detached and attached units across a range of styles, from traditional to fully modern. Free consultations come with a property evaluation; expect zoning questions before design comes up. 

Address: 1809 15th Ave Apt B, Seattle, WA 98122

Facebook: https://www.facebook.com/SeattleADUSolutions/

Seattle Modern Buildings

Detached ADUs and custom homes share the project list at Seattle Modern Buildings, a full-service design-build firm working across Washington state. The work tilts modern, with the firm handling design, permitting, and construction in-house. An AADUs on 45th Ave project is featured for clients researching attached units specifically. Homeowners who approach the ADU as architecture rather than as a packaged product end up here often. 

Address: 8305 Dallas Ave S, Seattle, WA 98108

SKYDADU

Tod Sakai founded Sockeye Homes in 2007 and runs SKYDADU as its DADU-focused arm. Sakai was an active voice in passing Washington HB 1337, the 2023 law requiring cities to allow up to two ADUs per lot, and he serves on the state's Legislative Policy Council. SKYDADU offers fixed-price, fixed-timeframe DADU packages, which is unusual in custom construction and the firm's central pitch. Sockeye Homes itself has been recognized as the most awarded company by the Building Industry Association of Washington. The firm works primarily in greater King County, with marketing that emphasizes rental income and financing strategies more than design aesthetics. Sakai still speaks at conferences and sits on industry panels, and that engagement shapes what working with the firm feels like day to day. 

Facebook: https://www.facebook.com/skydadu/

Tenhulzen Construction

The Tenhulzen family has been remodeling on the Eastside for more than a quarter century, with roots that go back to a 1979 family business. The company's CAPS certification, for aging-in-place specialization, matters more for ADUs used as in-law units than people often realize. They serve King and Snohomish counties, fitting ADU projects inside a remodeling practice that handles bigger jobs too. Best for multigenerational projects where accessibility planning needs to be designed in, not bolted on later. 

Address: 16900 9th Ave. SE Mill Creek, WA 98012

Facebook: https://www.facebook.com/TenhulzenTPCP

The DADU Guy

The DADU Guy specializes in premium DADUs across the Seattle area, running a concept-to-keys process that handles design and construction under one team. The firm publishes its model lineup with pricing openly discussed, which is unusual in this category. The brand is positioned at the high end, not the budget end; expect to pay for finishes and craftsmanship, not the cheapest path to permit. 

Instagram: https://www.instagram.com/thedaduguy/

The DADU Pro

AG Construction & Remodeling, a Seattle design-build firm working across Washington state, runs The DADU Pro as its DADU-focused brand. Their process is unusually transparent for the category: a lot pre-analysis, on-site walk, written cost breakdown including materials and timeline, full permit set submission, then about four months of construction with daily photo updates and a live project schedule. The firm offers financing up to $750,000 through partners, which clears one of the most common roadblocks for ADU projects. A one-year warranty is standard, with walkthroughs at one and eleven months. The work centers on custom backyard homes and cottages. Property evaluations are the entry point, telling clients what their lot can support before any design work begins.

Address: 11811 NE 1st St, Suite 309D, Bellevue, WA 98005

Facebook: https://www.facebook.com/thedaduprocom

Volcano Builders

Volcano Builders runs as a family-owned general contractor in Bellevue, taking on ADUs and garage conversions across Seattle, Bellevue, Monroe, and the rest of the Eastside. The company describes itself as a three-generation building legacy, with architects and engineers assigned in-house to each project. ADU projects sit inside a wider remodeling practice, with kitchens, baths, and additions making up most of the calendar. The generalist positioning is the firm's strength for multi-project clients and a limitation for anyone wanting a dedicated ADU specialist. 

Address: 1750 112th Ave NE, Bellevue, WA, United States, 98004

Facebook: https://www.facebook.com/volcanobuilders

Snohomish County and the north Eastside ADU builders

AddSpace DADU

AddSpace DADU was started by Danial Dorran, a commercial construction veteran, and David Anderson, a custom-furniture craftsman, who saw too many DADU projects stall in the planning phase and built their company around getting clients past it. Every subcontractor on the firm's list has to have at least ten years in their trade, which functions as a hidden quality filter most clients won't see. They work in Seattle, the eastside, and across most of Snohomish County, including Lynnwood, Edmonds, Everett, Marysville, and Monroe. Most of what they build is fully custom, with a handful of Seattle pre-approved designs available for clients who want to skip the design phase. 

Address: 2027 196th St SW Suite A106 Lynnwood WA, 98036

Cascadia ADU

Cascadia ADU operates out of Snohomish and offers either à la carte or full turnkey service, depending on how much of the project a client wants to manage. The plans shop sells six ADU designs separately for owner-builders, alongside the firm's full design-build construction service. Once permits are in hand, construction typically wraps in 8 to 10 weeks, with electrical work handled by an in-house crew. Owner Umar runs the company; calls go through him directly, which is part of the small-shop appeal. 

Instagram: https://www.instagram.com/cascadiadesignandbuild

MacCoy Home Solutions

MacCoy Home Solutions has been running out of Lynnwood since 2014 under Aaron MacCoy, with ADU and DADU work alongside the kitchen, bath, and outdoor-living projects that anchor the company. The firm took the BBB's 2023 Torch Award for Ethics in the Washington small business category, plus a first-place REX Award from the Master Builders Association for outdoor living in 2024. They serve Edmonds, Lynnwood, Mill Creek, Mukilteo, Woodinville, and into Seattle and the eastside. If you're in the north suburbs and want a contractor whose award shelf includes ethics recognition, MacCoy belongs on the shortlist. 

Address: 16830 Olympic View Dr, Lynnwood, WA 98037

Facebook: https://www.facebook.com/maccoyhomesolutions/

Tacoma and Pierce County ADU builders

Gordon T. Jacob

Five consecutive years of South Sound Magazine recognition (Best Remodeler 2019 through 2023, then Best Builder in 2025) put Gordon T. Jacob near the top of any Tacoma list. The family-run contractor is led by Chris Dunayski, with work that spans DADUs, middle housing (stacked duplexes, townhomes, and small apartment buildings legalized by Washington's 2023 housing law), and traditional home remodels. Five standard DADU floor plans are published with starting prices, with the studio model beginning at $186,000 and full builds typically wrapping in around six months. Dunayski talks about Tacoma housing policy as much as he talks about construction, which some clients find energizing and others find more conversation than they wanted. The same crews building townhomes also build the DADUs, which means clients get a builder used to navigating tight Tacoma lots. 

Facebook: https://www.facebook.com/gordontjacob

Tacoma DADU

Matt Rody runs Tacoma DADU as a small family-of-builders shop focused exclusively on detached units in Pierce County. The 40-plus years of Puget Sound building experience referenced on the company's site comes from the leadership, not the company itself, which was founded in 2020 to capitalize on Tacoma's loosening DADU rules. Turnkey pricing is unusually inclusive, covering permits, design, foundation, every utility connection in the unit, the full appliance package, and even the washer and dryer. Published models include the Baker and the Rainier, with customizations available for the inevitable lot-specific quirks. The firm spends serious time on Pierce County zoning specifics, including septic-related feasibility issues that can disqualify a lot before design starts. Rody handles intake personally and walks the lot before any work begins, which is the practical reason most clients pick them over a larger shop. 

Instagram: https://www.instagram.com/tacomadadu/

Southwest Washington ADU builders

MyADU

MyADU spun out of Shaffer Inc. Custom Homes in 2019 as Clark County's first dedicated ADU builder, eventually becoming its own LLC under Luke and Bill Shaffer in 2022. The team builds between 10 and 15 ADUs a year, with leadership backed by more than three decades of custom-home experience. Their Vancouver showroom is unusual in this category, since most ADU builders ask clients to make material decisions from photos rather than in person. They work across Clark County and cross the river into the Portland market, which makes them one of the few specialists working both sides of the state line. Their typical client wants a smaller, focused team and the option to actually walk through finishes before signing anything. 

Address: 10110 NE 13th Ave Vancouver, Washington, 98686

Facebook: facebook.com/myaduwa

Wolf Industries

Wolf Industries builds modular ADUs out of a factory in Battle Ground, north of Vancouver, and ships finished units across Washington and Oregon. More than 500 homes have been placed in the last five years, with roughly half in Clark County. The factory model creates a meaningful cost difference: a unit built indoors on an assembly line skips weather delays and reduces on-site labor, with the company aiming to hand keys over within six weeks of arrival on site. The trade-off is design flexibility, since Wolf builds from a model lineup rather than from custom drawings, which makes them faster but less personalized than site-built competitors.

Address: 607 SE Eaton Blvd, Battle Ground WA 98604

Facebook: https://www.facebook.com/wolfind.tinyhomes

Connect with the right ADU builders using Block Renovation

The Washington-based ADU contractor you choose is arguably the most important decision you’ll make on the entire project. The differences show up later, in scope clarity, payment structure, and how change orders get handled.

That's the gap Block set out to close. We pair homeowners with vetted local contractors with each scope reviewed by Block's experts to catch missing line items and red flags before quotes come back. We help Washington homeowners not only tackle ADUs, but also garage renovations, attic conversions, home addition construction, and even new home builds.

Payments run through Block on a progress-based schedule, so contractors get paid as work gets done, not before. In short, we work hand-in-hand with both you and the Washington builders to ensure a satisfactory ADU project from end-to-end.

CTA: About Block