Best adu — 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
Defining the best ADU involves prioritizing functional space, energy efficiency, and structural integrity. A great unit maximizes every square foot, providing a comfortable living environment that blends well with your main house architecture. We guide you through the process of selecting the right size and floor plan to ensure your new space serves its intended purpose for years to come. Exact pricing confirmed free on the call.
Frequently asked in Hillsboro
What are the ADU cost considerations in Hillsboro?
What is a local ADU in Hillsboro?
A local ADU in Hillsboro refers to an accessory dwelling unit constructed and permitted in accordance with Hillsboro's specific zoning ordinances and building codes. This ensures compliance with local regulations regarding size, setbacks, parking, and design. It means the ADU is legally established and integrated into the community according to city standards. Working with local professionals who are familiar with these specific Hillsboro requirements is crucial for a smooth and compliant ADU project.
What is a detached accessory dwelling unit in Hillsboro?
What is the cost of an accessory dwelling unit in Hillsboro?
What accessory dwelling unit services are available in Hillsboro?
Where can I find an accessory dwelling unit near me in Hillsboro?
What is a prefab ADU in Hillsboro?
A prefab ADU in Hillsboro is a prefabricated accessory dwelling unit, meaning it's constructed in sections at a factory and then transported to your site for assembly. This method often leads to faster construction times and potentially more consistent quality control due to the controlled factory environment. Prefab ADUs must still comply with all Hillsboro's zoning and building codes. They are designed to be durable, energy-efficient, and a cost-effective housing solution, offering flexibility for homeowners looking to add secondary dwelling space to their property.
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: The Orenco Station, The Goldy Neighborhood, The North Hills Neighborhood, The South Hills Neighborhood, The Downtown Hillsboro Area — and every surrounding area.
Areas we serve
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