Detached ADU Portland: What You Can Build on Your Lot

Building a detached ADU in Portland is one of the most popular ways to add living space,
rental income, or multigenerational housing to a property.
Detached ADUs offer privacy and flexibility, but they must comply with zoning rules,
setbacks, height limits, and lot constraints before design begins.

What Is a Detached ADU?

A detached ADU is a standalone accessory dwelling unit that is separate from the main house.
In Portland, detached ADUs are commonly built in rear yards and may include
single-story layouts or two-story configurations depending on zoning allowances.

Because detached ADUs are treated as separate structures,
they require careful evaluation of lot coverage, setbacks, and building height
before plans are prepared.

Detached ADU Zoning Rules in Portland

Most residential zones in Portland allow detached ADUs, but zoning alone does not guarantee approval.
A feasibility review must confirm that your lot meets minimum requirements such as
rear and side yard setbacks, maximum building height, allowable floor area,
and separation from the primary dwelling.

Why Feasibility Comes Before Design

Many detached ADU projects are delayed because zoning and site constraints
are discovered after drafting begins.
Confirming detached ADU feasibility in Portland before design
prevents redesigns, lost time, and unexpected permit corrections.

How the ADU Feasibility Wizard Helps

Our interactive

ADU Feasibility Wizard for Portland

evaluates detached ADU potential across the Portland PDX region,
including Beaverton, Gresham, Hillsboro, Salem, Keizer, and Marion County.

For a $250 upgrade, the Wizard allows you to download preliminary ADU plans
or upload your own plans to confirm zoning compliance, setbacks,
and development potential before drafting begins.

Detached ADU Design Considerations

Detached ADUs often require strategic placement to maintain privacy,
meet fire separation requirements, and stay within height and floor area limits.
Two-story detached ADUs may be allowed on some lots, but feasibility must be verified first.

Start With Feasibility Before You Build

If you’re considering a detached ADU in Portland, start with feasibility first.
Use the

ADU Feasibility Wizard

to evaluate your lot, confirm zoning allowances, and move forward with confidence.