ADU Architect in Eugene, Oregon

Eugene is one of the most progressive cities in Oregon when it comes to accessory dwelling units. The city has actively encouraged ADU construction for over a decade, and state legislation — particularly Senate Bill 391 and subsequent amendments — has removed many of the barriers that once made ADUs difficult to permit. There are no off-street parking requirements for ADUs in Eugene. Owner-occupancy mandates have been relaxed. System development charges have been reduced. The result is a regulatory environment that genuinely supports the construction of small, well-designed secondary housing.

In Eugene, a detached ADU can be up to 800 square feet or 10 percent of the lot area, whichever is less, though lots zoned R-1 allow units up to 900 square feet under certain conditions. Attached ADUs — built as additions to the primary home — follow different size calculations. Setback requirements for detached ADUs have been reduced to as little as five feet from side and rear property lines, and building height can reach up to 18 feet. These numbers shape the design from the first sketch, and understanding them precisely is the difference between a smooth permit process and months of revisions.

We have designed ADUs throughout Eugene — detached backyard cottages in the Amazon neighborhood, garage-top units in Whiteaker, attached suites in Cal Young built for aging parents. Each one is a complete home in miniature: kitchen, bathroom, sleeping area, storage, and some connection to the outdoors that makes 600 or 800 square feet feel genuinely livable rather than merely adequate. Small-space design is its own discipline, and it demands more architectural attention, not less.

An ADU in Eugene typically costs between $150,000 and $350,000 to build, depending on size, site conditions, and finishes. The investment produces either rental income — Eugene's rental market near the University of Oregon is strong year-round — or multigenerational flexibility that adds both function and value to your property. In either case, the design quality of the ADU matters. A well-designed unit rents for more, appraises for more, and adds rather than detracts from the character of your primary home.