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 backyard ADU is a detached small home built on your property, separate from your main house. People typically build these to create extra living space for family members, as a private home office, or to gain additional rental income. Because they are freestanding, you will need to consider utility hookups, site access for crews, and local setback requirements. Costs vary based on the foundation type and utility connections. Exact pricing confirmed free on the call.
Frequently asked in Hillsboro
What is the process for accessory dwelling unit construction in Hillsboro?
Accessory dwelling unit construction in Hillsboro begins with design and permitting, which requires submitting plans that comply with the city's zoning ordinances and building codes. Once permits are secured, site preparation and foundation work commence, followed by framing. Installation of utilities, including plumbing, electrical, and HVAC, is a critical phase. Exterior finishes and roofing are applied, and finally, interior work, such as insulation, drywall, and fixtures, is completed. The experienced crew that comes out ensures adherence to Hillsboro's quality standards throughout the process.
How much does an accessory dwelling unit cost in Hillsboro?
What does accessory dwelling unit mean in Hillsboro?
In Hillsboro, Oregon, an accessory dwelling unit (ADU) is defined as a secondary, independent living space on a lot with an existing single-family home. It must include its own kitchen, bathroom, and sleeping area. ADUs can be attached to the primary dwelling or be a detached structure, like a backyard cottage. Hillsboro's zoning regulations outline specific requirements regarding size, placement, and occupancy to ensure these units integrate well within neighborhoods. Understanding this definition is key for any ADU project.
What are the requirements for an ADU permit in Hillsboro?
To obtain an ADU permit in Hillsboro, you must submit detailed architectural plans that meet the city's zoning ordinances and building codes. These plans should demonstrate compliance with setback requirements, maximum size limitations, and any specific parking provisions. The application undergoes review by the Hillsboro planning and building departments. Ensuring your plans align with these criteria is vital for a smooth permitting process. We can help guide you through each step of this procedure.
What are the benefits of a 24-hour ADU service?
While ADU construction itself is not a 24-hour service due to standard working hours and permitting processes, the concept of rapid response for urgent issues related to existing ADUs is valuable. For immediate structural problems or critical system failures in an established unit, having access to professionals who can respond quickly is important. However, new ADU construction and significant renovations follow planned timelines. We focus on efficient project management to complete new builds in a timely manner, adhering to all safety and quality standards in Hillsboro.
Can I get an accessory dwelling unit contractor in Hillsboro?
What are the best accessory dwelling unit options for Hillsboro?
The best accessory dwelling unit option for Hillsboro depends on individual needs and property characteristics. A detached backyard cottage might be ideal for maximizing privacy and rental potential on larger lots, while an attached ADU could be more cost-effective for smaller properties or when proximity to the main house is desired. Factors like local zoning regulations, your budget, and the intended use of the ADU all influence the optimal solution for your Hillsboro property. We help you evaluate these elements.
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, Brookwood, Downtown Hillsboro, South Hillsboro, West Union — and every surrounding area.
Areas we serve
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