Accessory dwelling unit permit cost — Spokane, 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.

Frequently asked in Spokane

Also serving nearby: Spokane Valley · Yakima · Bellevue · Renton · Kirkland

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

Service area details

Serving all of Spokane — population 229,447; about 3,336 residents per square mile across 68.8 sq mi. ZIP codes covered include 99201, 99202, 99203, 99204, 99205, 99206, 99207, 99208.

Neighborhoods served in Spokane: South Hill, Browne's Addition, Audubon, Manito, Minnehaha — and every surrounding area.