Northwest ADU Bellevue

ADU Builders in Washington — Custom Detached ADUs, Garage Conversions & Build-Ready Plans

Northwest ADU is a full-service ADU contractor serving homeowners across Western Washington. They specialize in designing and building high-quality accessory dwelling units tailored for rental income, multigenerational family living, and long-term property value. From initial feasibility through final inspection, they manage every phase of the project under one coordinated contract.

Their core services include:

1. Detached ADU construction — standalone backyard homes with full privacy and independent living spaces
2. Garage conversion contractor services — transforming existing garages into code-compliant, fully functional living units
3. Basement conversions — converting underutilized lower-level space into livable square footage
4. Build-ready ADU plans — professionally designed, permit-aligned floor plans that accelerate approvals and reduce costs

As dedicated accessory dwelling unit builders, they focus exclusively on ADU projects — not general remodeling — which allows for efficient, well-coordinated builds with clear timelines and transparent pricing.

Detached ADU Construction — Standalone Backyard Homes

A detached ADU is an independent residential structure built on the same lot as the primary home, typically located in the backyard. It includes its own kitchen, bathroom, living area, and private entrance. As a detached ADU builder, Northwest ADU offers multiple floor plan configurations to suit different lot sizes and homeowner goals:

1. Studio ADUs (400–600 sq ft) — compact open-plan layouts ideal for rentals or guests
2. One-Bedroom ADUs (600–800 sq ft) — separate bedroom, full kitchen, and strong rental appeal
3. Two-Bedroom ADUs (800–1,000+ sq ft) — maximum allowable size in many municipalities, suitable for families or higher rental income

Detached ADUs typically range from $180,000 to $350,000+ depending on size, site conditions, utility requirements, and finish level. The full project timeline — from design through final inspection — is approximately 6–10 months, with permit timelines varying by city.

Their process as a backyard cottage builder includes a thorough feasibility and site evaluation before design begins. They assess lot size, zoning designation, setback requirements, height limits, utility capacity, stormwater requirements, and access conditions. This upfront planning prevents costly delays and budget surprises during construction.

Utility and infrastructure planning is also handled during the design phase. This includes water and sewer connections, electrical service upgrades, and gas line extensions where applicable — ensuring all systems are properly coordinated before construction begins.

Build-Ready ADU Plans & Full-Service Project Management

For homeowners who want to move quickly without sacrificing quality, Northwest ADU offers build-ready ADU plans — professionally designed, permit-aligned floor plans that streamline the approval and construction process. These plans provide efficient square footage use, predictable construction costs, and a shorter design phase compared to fully custom architectural drawings.

Key advantages of build-ready plans include:

1. Faster permit submission
2. Reduced architectural fees
3. Pre-optimized layouts for common lot configurations
4. More predictable budgeting from the start

Whether a homeowner chooses a build-ready plan or a fully custom design, Northwest ADU manages the entire construction process from start to finish. Their structured project workflow includes:

1. Initial consultation and site review
2. Feasibility study and budget planning
3. Architectural design and engineering
4. Permit submission and city approvals
5. Licensed, insured construction
6. Final inspection and project handover

They serve homeowners throughout Pierce, King, and Snohomish Counties in Western Washington, with deep expertise in local zoning regulations, permitting requirements, and municipal coordination. Their permit-first planning approach and structured project management make them a trusted choice for homeowners looking to add a granny flat, in-law suite, or income-generating rental unit to their property.

ADUs are widely recognized as one of the strongest long-term investments a homeowner can make — offering rental income potential, increased resale value, and flexible housing solutions for multigenerational families. Northwest ADU's focus on quality craftsmanship, transparent pricing, and clear communication at every stage ensures homeowners can build with confidence.