Northwest ADU

Northwest ADU is a full-service ADU design, permitting, and construction company specializing exclusively in accessory dwelling units throughout Western Washington. The company was created to focus specifically on ADU projects and is backed by the construction expertise of Northwest BNR. Its services cover the process from feasibility and design through permitting, construction, final inspection, and handover.

An accessory dwelling unit (ADU) — also known as a granny flat, in-law suite, backyard cottage, casita, or secondary dwelling unit — is an independent living space located on the same property as a primary residence. Northwest ADU specializes in several ADU formats designed for rental income, multigenerational living, guests, and long-term property value.

ADU Services

1. Detached ADUs: Northwest ADU designs and builds standalone backyard homes with their own living areas, kitchens, bathrooms, and private entrances. These can be used as rental units, guest houses, multigenerational living spaces, or private offices.
2. Garage Conversions: Existing garages can be converted into fully functional, code-compliant residential living spaces.
3. Basement Conversions: Underused basement areas can be transformed into comfortable apartment-style living spaces where permitted by local regulations.
4. Build-Ready ADU Plans: The company offers pre-designed, permit-ready ADU plans intended to streamline the design and approval process.

What Northwest ADU Offers Beyond Construction

Northwest ADU manages the ADU process under one coordinated service. Its initial feasibility work evaluates factors such as lot size, zoning, setbacks, height limits, utility capacity, stormwater requirements, access, and grading conditions before design begins.

Its design and planning stage includes floor plans, budgeting, and engineering, followed by permit submission and coordination with local authorities. Construction then covers the physical development of the ADU through final inspection and handover.

The company also emphasizes transparent pricing, realistic timelines, permit and zoning expertise, structured project management, and clear communication throughout the project.

Northwest ADU’s detached ADU options include studio layouts of approximately 400–600 square feet, one-bedroom layouts of 600–800 square feet, and two-bedroom configurations of 800–1,000+ square feet, depending on local regulations and property conditions.