Adu services — Seattle, WA

Last updated: September 24, 2026

In Seattle, the difference between a patch and a proper repair for an ADU often comes down to understanding the underlying structural integrity and code compliance, a detail the pros at AccessoryDwellingUnit Pros meticulously address. We are well-versed in King County's zoning regulations and the specific requirements of the City of Seattle's ADU program, which often involve detailed site plan reviews and adherence to strict setback and height limitations. Our initial consultations focus on providing a realistic assessment of your property's potential for an ADU, covering aspects like soil stability for foundations, access for construction vehicles, and the integration of plumbing and electrical systems. This includes discussing material durability in the Pacific Northwest climate and the long-term performance of various construction methods. We aim to demystify the entire process, from initial design to final inspection. Call us today for a comprehensive, no-cost consultation.

What affects the price

Building an ADU is a custom project, so costs vary based on your specific choices. Site conditions are the biggest factor; if your land requires significant grading, utility extensions, or foundation work, those expenses add up quickly. Choosing high-end finishes, custom cabinetry, or complex roof lines will also push the budget higher compared to a standard design. Prefabricated units often offer predictable costs, while custom site-built structures allow for more flexibility but can be harder to estimate upfront. Exact pricing confirmed free on the call.

About this service

ADU services simplify the complex process of turning unused yard space into a functional, independent living unit. This involves architectural drafting, structural engineering, and managing municipal building departments to secure necessary approvals. You should look for these services when you are ready to expand your home’s footprint for rental income, guest accommodations, or multi-generational living. Engaging experts ensures the project stays compliant with state codes while meeting your specific design goals for a secondary dwelling.

Frequently asked in Seattle

Also serving nearby: Kirkland · Bellevue · Renton · Kent · Federal Way

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More on this: HUD ADU resources — ADU policy and financing research.

Service area details

Serving all of Seattle — population 755,078; about 8,989 residents per square mile across 84.0 sq mi. ZIP codes covered include 98101, 98102, 98103, 98104, 98105, 98106, 98107, 98108.

Neighborhoods served in Seattle: West Seattle, University District, Ballard, Capitol Hill, Queen Anne, Green Lake — and every surrounding area.