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: size varies by zoning — see official source (max height: varies — see official source). Attached ADU: size varies by zoning — see official source.
| Type | Max Size | Max Height |
|---|---|---|
| Detached ADU | See official source | See official source |
| Attached ADU | See official source | See official source |
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: Varies.
| 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 | See official source |
Permit Timeline
Eugene ADU Permit Timeline: Eugene Planning and Development processes ADU permits. Standard ADU: 4-8 weeks plan review. 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: follows zone standard. Side setback: no minimum. Rear setback: no minimum.
Parking Requirements
Parking Requirements: Reasonable local regulations relating to siting and design does not include requirements to construct additional off-street parking for accessory dwelling units
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
Statewide Preemption
ADU Preemption
Oregon state law preempts local ADU rules — local governments cannot impose stricter standards.
View Oregon preemption detailsState 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
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.. Total estimated permit fees are $2,500–$7,000 permit fees plus SDCs.
Do I need extra parking for an ADU in Eugene?
Eugene parking rules for ADUs: Reasonable local regulations relating to siting and design does not include requirements to construct additional off-street parking for accessory dwelling units
Do I have to live on-site to have an ADU in Eugene?
Owner-occupancy requirement in Eugene: Reasonable local regulations relating to siting and design does not include owner-occupancy requirements of either the primary or accessory structure for accessory dwelling units
Source: Eugene Code Title 9, Section 9.2340 — Accessory Dwelling Units; Oregon Revised Statutes 197A.420. Last verified April 6, 2026. View source