Accessory Structures in Eugene, OR

If you live in Eugene or are thinking about moving there, accessory structures are one of those things you probably won't think about until they affect you directly. Eugene has 2 specific rules on the books covering different aspects of accessory structures, and some of them might surprise you.

ADU Rules

Eugene allows one accessory dwelling per lot in every residential zone under EC 9.2751(17), capping an attached ADU at 10 percent of the lot area or 800 square feet, whichever is smaller. Within 60 feet of the front lot line it needs only a 5-foot interior setback; height then follows the main house's limit under Table 9.2750.

Key details: Max attached ADU size: 10% of lot or 800 sq ft, smaller controls. Interior setback (near front): 5 feet minimum. Detached ADU storage exclusion: 300-800 sq ft unheated space excluded. Minimum pedestrian walkway: 3 feet wide, hard-surfaced. Governing section: EC 9.2751(17).

EC 9.2751(17)(e) is explicit: failing to meet any accessory dwelling standard is a violation enforced under EC 9.0010 through 9.0280, Eugene's general land use enforcement chapter. That chapter's penalty section, EC 9.0275, sets a fine of up to $1,000 for each day the violation continues, confinement in jail up to 100 days, or both, in addition to stop-work or stop-use orders and withheld permits under EC 9.0270.

Shed & Carport Rules

Eugene caps accessory buildings, sheds, detached garages and workshops, at 10 percent of the lot area under EC 9.2751(16), with a tighter 400-square-foot limit inside the Amazon, Fairmount and South University neighborhoods. Interior yard setbacks start at 5 feet and slope back once the wall passes 8 feet, capping most sheds at 25 feet.

Key details: Max size, R-1 general: 10% of lot area. Max size, Amazon/Fairmount/S. Univ.: 400 sq ft. Interior yard setback: 5 feet minimum. Max height, R-1 general: 25 feet, slopes past 8 ft. Max height, area-specific R-1: 18 feet.

EC 9.0275 makes violation of any Chapter 9 land use standard, including these accessory building limits, punishable by a fine of up to $1,000 for each day the violation continues, confinement in jail up to 100 days, or both. Using an oversized or unpermitted accessory building as a residence without the required deed restriction is also grounds for enforcement action, since EC 9.2751(16)(a)3 conditions the extra plumbing fixture on that recorded restriction.

The Bottom Line

Eugene's accessory structures rules are a mixed bag. Some areas are strict, others are relaxed, and the details matter. The best approach is to check the specific rule that applies to your situation rather than assuming Eugene is broadly strict or permissive.

Keep in mind that Eugene can amend these rules at any council meeting. For the most current version of any rule mentioned here, check the specific ordinance page, where we track updates as they happen.