Cost to build accessory dwelling unit — Spokane Valley, WA
Last updated: September 24, 2026
What affects the price
Building an ADU involves variables that shift your total investment. The footprint size and complexity of the architectural design are primary factors. Are you planning a detached unit that requires new utility trenching, or is this a garage conversion that uses existing plumbing? Site accessibility, soil conditions, and your choice of finishes—like luxury flooring versus standard options—also play significant roles. Permitting fees vary widely depending on your local municipality and current zoning requirements. Exact pricing confirmed free on the call.
About this service
The expense of building an ADU varies based on site preparation, whether you need to run new sewer or electrical lines, and the level of interior customization you choose. Larger custom builds naturally require more materials and labor than simpler conversions. We provide exact pricing confirmed free on the call.
Frequently asked in Spokane Valley
What about ADUs in New Hampshire?
Can I build a backyard ADU in Spokane Valley?
How can I find an affordable ADU in Spokane Valley?
What's the process for ADU rentals in Spokane Valley?
What are ADU services in Spokane Valley?
What are accessory dwelling unit homes?
Accessory dwelling unit (ADU) homes have a secondary, independent living space on the property. This unit has its own entrance, kitchen, and bathroom. It can be attached or detached. ADUs offer flexibility for guests, renters, or family. They increase a home's utility.
What is the permit cost for an ADU in Spokane Valley?
Also serving nearby: Spokane · Yakima · Bellevue · Renton · Kirkland
More on this: HUD ADU resources — ADU policy and financing research.
Service area details
Serving all of Spokane Valley — population 108,235; about 2,869 residents per square mile across 37.7 sq mi.
Neighborhoods served in Spokane Valley: Opportunity, Millwood, Chatter Creek, Ponderosa, Green Acres — and every surrounding area.
Areas we serve
Browse by state, then city.