Adu construction — Federal Way, WA
Last updated: September 24, 2026
What affects the price
Building an ADU involves several moving parts that shape your total investment. The final figure depends heavily on whether you choose a prefab unit or a custom build from the ground up. Site conditions are another major factor; if your property requires extensive grading, utility trenching, or foundation work, costs will climb. You also have to consider your choice of finishes, like high-end appliances or custom cabinetry. Navigating local permit fees and impact assessments also adds to the total.
About this service
Frequently asked in Federal Way
What's involved in renting out an ADU in Federal Way?
What is an ADU unit in Federal Way?
How can I get an ADU quote in Federal Way?
What's the cost of an ADU in Federal Way?
What ADU permits are needed in Federal Way?
Can I get an ADU estimate quickly in Federal Way?
What is an affordable accessory dwelling unit in Federal Way?
Also serving nearby: Tacoma · Kent · Renton · Seattle · Bellevue
More on this: HUD ADU resources — ADU policy and financing research.
Service area details
Serving all of Federal Way — population 97,701; about 4,375 residents per square mile across 22.3 sq mi. ZIP codes covered include 98003, 98023, 98063, 98093.
Neighborhoods served in Federal Way: The Commons, Woodmont, Mirror Lake, Panther Lake, Chase Lake, Brighton — and every surrounding area.
Areas we serve
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