Adu building — 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
ADU building covers the entire process of planning, permitting, and constructing a secondary home on your property. This involves drafting site plans, getting approval from your local planning department, and handling the structural work from foundation to roof. You need this service when you are ready to officially break ground on your project. Costs are driven by the complexity of the design, site preparation, and finish materials. Exact pricing confirmed free on the call.
Frequently asked in Hillsboro
What are the accessory dwelling unit services available in Hillsboro, Oregon?
What are affordable accessory dwelling unit options in Hillsboro?
What does 'accessory dwelling unit' mean in the context of Hillsboro?
What is the cost for an accessory dwelling unit in Hillsboro?
What are homes with mother-in-law suites like in Hillsboro?
What is the process for an ADU estimate in Hillsboro?
What are the best ADU options for Hillsboro residents?
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: Raleigh Hills, Evergreen, South Hills, Northwest Hillsboro, Downtown Hillsboro — and every surrounding area.
Areas we serve
Browse by state, then city.