Prefabricated accessory dwelling unit — 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
A prefab ADU is a structure built off-site in a factory and then transported to your property. Since the components are manufactured in a controlled environment, these units often have shorter construction timelines than traditional builds. You might choose this if you want to minimize noise and debris in your backyard. Costs depend on the complexity of the design, the quality of materials, and the foundation work required. Exact pricing confirmed free on the call.
Frequently asked in Hillsboro
What are the affordable accessory dwelling unit options in Hillsboro?
What are the requirements for homes with mother-in-law suites in Hillsboro?
Where can I find ADU builders in Hillsboro, OR?
What modular accessory dwelling units are suitable for Hillsboro?
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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: Orenco Station, Downtown Hillsboro, Brookwood, Haworth, Walnut Creek — and every surrounding area.
Areas we serve
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