Cost of accessory dwelling unit — Renton, WA

Last updated: September 24, 2026

What affects the price

Building an ADU involves several moving parts that shape your total budget. The biggest factor is whether you choose a prefabricated unit or a custom build on-site. Site preparation is also significant; if your land requires extensive grading, utility trenching, or foundation work, costs will climb. Your choice of finishes—like kitchen cabinetry, flooring, and siding materials—also shifts the bottom line. We help you navigate these variables to find a setup that fits your property. Exact pricing confirmed free on the call.

About this service

The total price for an ADU depends on several moving parts, including the square footage, your foundation type, and local labor rates. Choosing high-end finishes or complex site prep will naturally increase the budget, while standard layouts help keep things manageable. Exact pricing confirmed free on the call.

Frequently asked in Renton

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

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

Service area details

Serving all of Renton — population 104,491; about 4,438 residents per square mile across 23.5 sq mi. ZIP codes covered include 98055, 98056, 98057, 98058, 98059.

Neighborhoods served in Renton: Bryn Mawr-Skyway, East Renton Highlands, Fairwood, Kennydale, South Renton, Talbot Hill — and every surrounding area.