Accessory dwelling unit 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
The total cost for an ADU depends on whether you are building a new detached structure, converting an existing garage, or adding an attached unit. Factors like plumbing installation, electrical panel upgrades, and custom interior finishes drive the final investment. Understanding these variables early helps you determine the feasibility of your project. Exact pricing confirmed free on the call.
Frequently asked in Hillsboro
What are the advantages of modular ADUs in Hillsboro?
What does 'accessory dwelling unit' mean in Hillsboro?
What is the cost of an ADU in Hillsboro?
What are the best ADU options for Hillsboro properties?
What are the rules for ADU permit costs in Hillsboro?
What are accessory dwelling unit homes in Hillsboro?
What are the benefits of ADU rental 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: Orenco Station, The %, The %, The %, The % — and every surrounding area.
Areas we serve
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