Adu cost — Hillsboro, OR
Last updated: September 24, 2026
What affects the price
Building an ADU is a custom project, so costs vary based on your specific choices. Site conditions are the biggest factor; if your land requires significant grading, utility extensions, or foundation work, those expenses add up quickly. Choosing high-end finishes, custom cabinetry, or complex roof lines will also push the budget higher compared to a standard design. Prefabricated units often offer predictable costs, while custom site-built structures allow for more flexibility but can be harder to estimate upfront. Exact pricing confirmed free on the call.
About this service
Your ADU budget is influenced by the type of foundation, the connection of plumbing and electrical lines, and the materials used for the exterior and interior. Converting an existing structure is generally different from building a new foundation from scratch. Exact pricing confirmed free on the call.
Frequently asked in Hillsboro
What are the requirements for a modular ADU in Hillsboro?
Can I get an ADU permit in Hillsboro?
What are the best ADUs for my property in Hillsboro?
What are accessory dwelling unit services in Hillsboro?
Can I build an accessory dwelling unit for rent in Hillsboro?
How do I find an ADU contractor in Hillsboro?
What is the cost of an accessory dwelling unit in Hillsboro?
Also serving nearby: Beaverton · Portland · Vancouver · Gresham · Salem
More on this: HUD ADU resources — ADU policy and financing research.
Service area details
Serving all of Hillsboro — population 107,730; about 4,168 residents per square mile across 25.8 sq mi. ZIP codes covered include 97123, 97124, 97129.
Neighborhoods served in Hillsboro: Brookwood, Walnut Creek, Raleigh Hills, North Plains, Orenco Station — and every surrounding area.
Areas we serve
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