Accessory dwelling unit construction cost — 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 cost of building an ADU depends on your choice of materials, the square footage, and whether you are doing a garage conversion or a new detached build. Site access and utility upgrades also play a big role in the final bill. Exact pricing confirmed free on the call.
Frequently asked in Renton
What's the deal with modular accessory dwelling units in Renton?
How do I get an ADU permit in Renton?
What factors influence accessory dwelling unit construction costs in Renton?
What makes a 'best' ADU for a Renton property?
How do I find reputable accessory dwelling unit companies in Renton?
What's involved in ADU construction from start to finish in Renton?
Are homes with mother-in-law suites common in Renton?
Also serving nearby: Kent · Bellevue · Seattle · Federal Way · Kirkland
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, Fairwood, Geneva, North Renton, South Renton, Talbot Hill — and every surrounding area.
Areas we serve
Browse by state, then city.
California (4)
All of California · Rialto · San Buenaventura (Ventura) · San Mateo · Vacaville