Portland ADU Builders

Build a custom ADU with Lamont Bros.

Building an ADU in Portland

Local Benefits & Opportunities

Portland has emerged as one of the most ADU-friendly cities in the country, thanks to progressive zoning reforms and a growing demand for flexible housing options. Under the city’s Residential Infill Project and related zoning changes, Portland allows accessory dwelling units on most residential lots, even permitting two ADUs on a single property under certain conditions. These relaxed zoning standards open a world of possibilities for homeowners who want to maximize the use of their property and invest in future value.

Whether you want to provide housing for your aging parents, support adult children moving back home, or generate rental income, ADUs deliver flexible living solutions while staying in line with Portland’s long-term housing strategies. From detached backyard cottages to garage and basement conversions, there are multiple ways to configure an ADU that fits your property and lifestyle.

Adding an ADU typically increases the overall value of your property. Many Portland area homeowners see strong returns on investment through long-term rentals, short-term stays (when permitted), or enhanced resale value. This makes an ADU not only a functional addition but also a smart financial decision.

ADU Rules in Portland

While Portland makes it easier to build ADUs than many other metro areas, there are still important local rules and standards that can impact your project. Key considerations include:

Zoning and property eligibility: Most residential lots can support an ADU, but zoning rules determine what’s allowed on your specific property.
Size limits: An ADU must remain smaller than the primary home, and maximum square footage may depend on your lot and configuration.
Placement and setbacks: Requirements around where an ADU can sit on the property (including distance from property lines) affect design options early.
Independent living requirements: A legal ADU must function as a true living space, including a separate entrance, kitchen, bathroom, and sleeping area.
Rental and usage rules: Regulations may influence how the unit can be rented (such as short-term vs. long-term), so it’s important to plan with the end goal in mind.
Tree preservation and site restrictions: Portland has strong tree protection policies, and existing trees or environmental overlays can limit buildable space.
Utility access and infrastructure: Your ADU may require upgrades or connections related to water, sewer, electrical, and stormwater management.
Neighborhood overlays and special conditions: Some areas have additional requirements that can affect design, permitting timelines, or what’s allowed.

At Lamont Bros., we help you plan around these Portland-specific details from the start. That means your ADU is designed to be permittable, compliant, and built for long-term success.