8 Best ADU Builders in Seattle, Washington
Verified ADU contractors and builders in Seattle, WA
Showing 1–8 of 8 listings
Better Builders
As your Seattle home remodeling experts, we create tailored ADU designs—perfect for generating rental income or offering a comfortable space for a loved one.
DIGS Construction & ADU Builders
DIGS specializes in ADU and DADU construction in Seattle and the surrounding area with custom designs, quality craftsmanship, and local expertise. At DIGS, we believe in the power of possibility and are excited to start this building journey with you.
Levite Construction CO
Transform your Seattle garage into valuable living space with expert conversion services that maximize your home's functionality and property value. We specialize in turning underutilized garages into beautiful bedrooms, home offices, studios, and recreational areas with professional design and seamless execution.
Modern Buildings LLC
We specialize in designing and constructing accessory dwelling units (ADUs) throughout the Seattle area, helping homeowners add valuable living space to their properties with expert planning and quality craftsmanship. From initial design consultation to final permits and construction, we handle every aspect of bringing your ADU project to life.
Puget Sound ADU Builders
At Puget Sound ADU Builders, we create functional and cozy ADUs (Accessory Dwelling Units) in Washington. Our company was founded by Tanya Mills and built on a passion for providing high-quality, affordable housing solutions that unite families.
Puzzle Construction Group
Transform your Seattle garage into functional living space with expert conversion services tailored to your home's unique layout and needs. From design through completion, we specialize in converting underutilized garages into bedrooms, home offices, studios, and more.
Seattle ADU Builders
Emerald ADU Builders Seattle is your favorite contractor when it comes to the design and building of the ADUs. You may have come across a prefab ADU Seattle going by different names like in-law units, granny flats, sidekick homes, backyard guest houses, and laneway homes among others.
Seattle Backyard Homes
Transform your Seattle backyard into additional living space with expert ADU construction tailored to your home and property. Our specialized builders design and build accessory dwelling units that maximize your land's potential while meeting local regulations and your family's needs.
Frequently Asked Questions — ADU Builders in Seattle
How much does it cost to hire an ADU builder in Seattle?
ADU construction costs in Seattle, Washington vary widely depending on size, type, and site conditions. Detached ADUs typically range from $150,000–$400,000+, while garage conversions and attached ADUs can be more affordable. Contact multiple builders in Seattle to get accurate quotes for your specific project.
How long does it take to build an ADU in Seattle?
In Seattle, the ADU construction timeline typically ranges from 6 to 18 months from permit application to move-in. Permitting alone can take 2–6 months depending on Washington local regulations. Prefab and modular ADUs often have faster timelines than site-built units.
Do I need a permit to build an ADU in Seattle?
Yes, a building permit is required for ADU construction in Seattle, Washington. Your ADU builder will typically handle the permit application as part of their service. Washington has adopted streamlined ADU permitting laws in recent years, which may reduce wait times.
What types of ADUs can be built in Seattle?
Common ADU types in Seattle include detached ADUs (backyard cottages), attached ADUs, garage conversions, basement conversions, and prefab/modular ADUs. The best type for your property depends on lot size, zoning, and budget. A local Seattle ADU builder can advise on what's allowed on your specific parcel.