ADU Rules in Eugene, OR (2026)
ADU rules, permit requirements, size limits, and fees for Eugene, OR. Source-cited from official municipal code.
Yes, ADUs are allowed in Eugene, OR.
Eugene, OR permits accessory dwelling units (ADUs) on residential properties. ADUs — also called granny flats, in-law units, backyard cottages, or secondary suites — are secondary housing units on a single-family or multifamily lot. State and local law actively preempts local restrictions, making ADU approval a streamlined ministerial process. In Eugene, the Eugene Planning and Development Department — Building Division handles ADU permit applications. Below you will find the current size limits, setbacks, fees, and timeline for building an ADU in Eugene.
ADU Size Limits
ADU Size Limits in Eugene: Detached ADU: up to 800 sq ft (max height: 20 feet). Attached ADU: 75% of primary dwelling up to 800 sqft. Oregon does not use the California JADU concept. Eugene Code limits detached ADUs to 800 sqft per Section 9.2340. Attached ADUs limited to 75% of primary dwelling, maximum 800 sqft. Eugene's University of Oregon proximity makes smaller (400-600 sqft) ADUs highly rentable to UO graduate students and faculty.
| Type | Max Size | Max Height |
|---|---|---|
| Detached ADU | 800 sq ft | 20 feet |
| Attached ADU | 75% of primary dwelling up to 800 sqft | Same as primary dwelling height limit per zone |
Permit Fees
ADU Permit Fees in Eugene: Plan check fee: $500–$2,500. Building permit fee: $900–$3,500. Impact fees: Eugene Metropolitan Wastewater and transportation SDCs apply — typically $5,000–$12,000. School fees: Eugene School District 4J SDCs may apply for new units. Total estimated permit cost: $2,500–$7,000 permit fees plus SDCs. Eugene Systems Development Charges (SDCs) for water, sewer, transportation, and parks can add $5,000–$15,000 for a new detached ADU. SDC deferrals available for income-restricted housing. Fee schedule: https://www.eugene-or.gov/planning/building/fee-schedule
| Fee Type | Amount |
|---|---|
| Plan Check | $500–$2,500 |
| Building Permit | $900–$3,500 |
| Impact Fees | Eugene Metropolitan Wastewater and transportation SDCs apply — typically $5,000–$12,000 |
| School Fees | Eugene School District 4J SDCs may apply for new units |
| Total Estimate | $2,500–$7,000 permit fees plus SDCs |
Permit Timeline
Eugene ADU Permit Timeline: Eugene Planning and Development processes ADU permits. Standard ADU: 4-8 weeks plan review. Eugene uses a ministerial Type I process for code-compliant ADUs per ORS administrative requirements. Construction typically 3-9 months. Eugene's older housing stock means many garage conversion ADUs are feasible with modest investment. Apply through the Eugene Planning and Development Department — Building Division online permit portal. Phone: (541) 682-5673.
Setback Requirements
ADU Setback Requirements in Eugene: Front setback: Same as zone standard. Side setback: 5 feet. Rear setback: 5 feet. Detached ADU: 5 ft side and rear setbacks per Eugene Code Section 9.2340.D. Front setback follows zone standard — R-1 zones require 20 ft front setback. Corner lots: street-facing setback applies per zone. Eugene's older platted lots (pre-1950s in Whiteaker, Fairmount, and South Eugene) often have smaller lot sizes making ADU placement a challenge.
Parking Requirements
Parking Requirements: No additional parking required for ADUs in Eugene. Oregon ORS 197A.420 prohibits local ADU parking requirements. Eugene has LTD (Lane Transit District) bus system providing transit access across the city.
Restrictions & Requirements
- ADU must comply with Eugene Code Title 9, Section 9.2340
- One ADU per single-family lot (additional units via HB 2001 middle housing path)
- ADU cannot be sold separately from primary dwelling
- Short-term rental of ADU (under 30 days) requires Eugene STR registration
- University Impact Area (near UO campus) may have additional housing density standards
- ADU must have permanent foundation — no RVs or mobile homes
How Many ADUs Are Allowed?
Number of ADUs Allowed in Eugene: Single-family lots: 1 ADU per single-family lot; up to 4 units by-right under Oregon HB 2001 middle housing. Multifamily properties: ADUs permitted in R-2, R-3, R-4 zones per Eugene Code. Eugene's middle housing rules (implementing HB 2001) allow up to 4 dwelling units on RS-zoned lots by-right. University neighborhood ADUs near UO can be rented to graduate students on 12-month leases for stable income.
Single-Family Lots
1 ADU per single-family lot; up to 4 units by-right under Oregon HB 2001 middle housing
Multifamily Properties
ADUs permitted in R-2, R-3, R-4 zones per Eugene Code
State Law & Preemption
State Preemption: Oregon House Bill 2001 (2019) requires Eugene to allow ADUs and middle housing by-right in all residential zones with 10,000+ population. Eugene had already been ADU-friendly before HB 2001. Oregon SB 458 (2021) allows lot splits. Owner-occupancy requirements are prohibited by ORS 197A.420. Eugene Code Title 9, Section 9.2340 implements state ADU standards.
Historic District Considerations
Historic District Requirements: Eugene has 3 historic districts where additional design review may be required for ADU construction. Design review approval is required before obtaining a building permit for properties in historic overlay zones. Eugene has 3 locally-designated historic districts: the Whiteaker neighborhood (Eugene's oldest residential neighborhood with 1880s-1920s housing stock), the Downtown Historic District, and a portion of the University area near UO. Eugene has been slower than Salem or Portland to establish historic district protections. Individual Landmark designations exist for significant buildings. The Whiteaker neighborhood has active historic preservation but also has Oregon's most active short-term rental and arts-district culture. Look up historic district boundaries at: https://www.eugene-or.gov/planning/historic-preservation
Frequently Asked Questions
Can I build an ADU in Eugene?
Yes. Eugene, OR allows accessory dwelling units. On a single-family lot you can build 1 ADU per single-family lot; up to 4 units by-right under Oregon HB 2001 middle housing.
How big can an ADU be in Eugene?
The maximum size for a detached ADU in Eugene is 800 square feet.
How long does it take to get an ADU permit in Eugene?
The typical ADU permit timeline in Eugene is Eugene Planning and Development processes ADU permits. Standard ADU: 4-8 weeks plan review. Eugene uses a ministerial Type I process for code-compliant ADUs per ORS administrative requirements. Construction typically 3-9 months. Eugene's older housing stock means many garage conversion ADUs are feasible with modest investment.. Total estimated permit fees are $2,500–$7,000 permit fees plus SDCs.
Do I need extra parking for an ADU in Eugene?
No, Eugene does not require additional parking for ADUs.
Do I have to live on-site to have an ADU in Eugene?
No, owner-occupancy is not required for ADUs in Eugene.
Source: Eugene Code Title 9, Section 9.2340 — Accessory Dwelling Units; Oregon Revised Statutes 197A.420. Last verified April 6, 2026. View source