Cost of accessory dwelling unit — Portland, OR

Looking for cost of accessory dwelling unit in Portland, OR? Call AccessoryDwellingUnit Pros for a contact a provider — no obligation. Licensed adu builders serve Portland and the surrounding area, and you'll get straight answers on timing and what affects the price.

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 investment for an ADU depends on several moving parts, including your property’s site conditions, the complexity of your site plan, and the high-end finishes you select. Whether you are building a detached cottage or converting a garage, costs vary based on utility connections and local labor rates. Exact pricing confirmed free on the call.

Frequently asked in Portland

What are the disadvantages of ADUs in Portland?

How much does an ADU cost in Oregon?

What are the rules for ADUs in California?

California has state laws that generally encourage ADU construction, but local cities still have their own specific ordinances. These rules often address maximum unit size, minimum setbacks, and parking requirements. You'll need to check the local regulations for the specific California city you're interested in.

Is ADU allowed in Maryland?

Yes, ADUs are permitted in many parts of Maryland, with regulations varying by county and municipality. For example, Baltimore City and Montgomery County have different rules concerning size, placement, and owner occupancy. It's crucial to research your local zoning laws.

What are the rules for ADU in California?

California's ADU laws aim to simplify the process, often setting statewide standards for unit size and setbacks. However, individual cities can impose additional local requirements, so it's always recommended to verify the exact rules with the planning department of the California city you're considering.

California has occasionally provided grant programs to help homeowners finance ADU construction. The availability and specific terms of these grants can differ, and they often have eligibility criteria. It's best to investigate current state and local initiatives for any available funding.

Also serving nearby: Vancouver · Beaverton · Gresham · Hillsboro · Salem

All cities in Oregon →

More on this: HUD ADU resources — ADU policy and financing research.

Service area details

630,498residents

4,723per sq mile

8ZIP codes served

Serving all of Portland — population 630,498; about 4,723 residents per square mile across 133.5 sq mi. ZIP codes covered include 97201, 97202, 97203, 97204, 97205, 97206, 97207, 97208.

Neighborhoods served in Portland: Pearl District, Hawthorne, Alberta Arts District, Sellwood-Moreland, Laurelhurst, Mississippi Avenue — and every surrounding area.