Everything homeowners need to know about building an accessory dwelling unit in Eugene - size limits, setbacks, permits, and the free pre-approved designs that make it one of the more straightforward Oregon cities to build in.
Last verified: August 2026
8/10 · Very ADU-friendly
800 sq ft*
Max ADU size
25 ft
Max height
Not required
Owner-occupancy
By-right
Permit type
This page summarizes Eugene's accessory dwelling unit standards under the Eugene Code (Land Use Code, Chapter 9) for general reference - it is not legal advice. Regulations change; always confirm current requirements with the City of Eugene Planning Division before designing or applying for permits. See sources below.
Zoning & size requirements
What you're allowed to build
ADU type
Max size
Max height
Notes
Detached (new build or garage conversion)
800 sq ft or 10% of lot area, whichever is smaller
25 ft, with a sloped height limit near interior property lines above 15 ft
Allowed on nearly all single-family lots, including alley-access and flag lots, with no minimum lot size
ADUs above garages have been allowed since Eugene's 2021 code update
Allowed zoning districts
ADUs are permitted with a single-family dwelling in all of Eugene's residential zones, with no minimum lot size and no public hearing required. Confirm your zone with the Planning Division.
Additional standards
Setbacks, parking & other rules
Setbacks
5 ft minimum from interior side and rear property lines; no setback is required where a detached ADU abuts an alley
Parking
No additional off-street parking required for the ADU itself
Units per lot
1 ADU permitted in addition to the primary dwelling
Owner-occupancy
Not required for either the primary home or the ADU
Building code
Must meet Oregon Residential Specialty Code dwelling-unit standards
Rental license
No separate long-term rental license. Short-term rental of an ADU is allowed with annual registration and a 30-day maximum stay, but only one unit on the property, not both at once, can operate as a short-term rental
Ordinance history
How Eugene's ADU rules got here
2017Oregon SB 1051. The state law requires cities over 2,500 people, Eugene included, to allow at least one ADU per single-family lot.
2018-2019First attempt appealed. Eugene's initial ADU ordinances (20594 and 20595) were appealed by the Home Builders Association, sending the city back to redraft its approach with the state Department of Land Conservation and Development.
2020Ordinance 20625 adopted. Effective February 22, 2020, it formally replaced "secondary dwelling" with "accessory dwelling" throughout city code and completed Eugene's compliance with the 2017 state law.
2019Oregon HB 2001. Signed August 8, 2019, the statewide law barred owner-occupancy and off-street parking requirements for ADUs.
Sept 2021Ordinance 20659 - a major liberalization. Effective September 17, 2021, it allowed ADUs on all single-family lots including alley-access and flag lots, raised the height limit to 25 ft, permitted ADUs above garages, and eliminated remaining parking, owner-occupancy, and density-calculation barriers.
2023Pre-Approved ADU Program launches. The city began offering ready-to-build designs, at least one free, that have already passed permit review.
Eugene's free pre-approved designs later became a model for other Oregon cities: Salem adapted Eugene's own plans for its 2023 ready-build ADU program. Oregon's Department of Land Conservation and Development reviews city ADU codes for compliance with state law; Eugene's early ordinances drew a builder-industry appeal for being too restrictive, but its current code hasn't been flagged for falling short of the state mandate.
Permit process
How Eugene ADU permitting works
1
Pre-application check
Confirm your zone and lot eligibility with Eugene Planning (541-682-5086) before you design.
2
Choose a pre-approved design or go custom
A pre-approved plan from the city's Pre-Approved ADU Program skips much of the design review since it's already been checked against the code.
3
Prepare your plan set
Site plan, floor plans, elevations, and the size calculation showing you're within 800 sq ft or 10% of your lot area.
4
Submit for a building permit
Eugene reviews ADUs administratively as a building-permit matter, with no public hearing required.
5
Pay System Development Charges
Budget roughly $7,000 for SDCs, recalculated at permitting and adjusted for inflation. Eugene lets you finance SDCs through the city over up to 10 years.
6
Construction & inspections
Once your permit issues, schedule the standard framing, plumbing, electrical, and final inspections.
Fees and review timelines change periodically - confirm current figures with the Eugene Planning and Development Department before budgeting.
Budgeting
What it costs to build an ADU in Eugene
Garage conversion
Roughly $70,000-$150,000, the least expensive path since the shell already exists
Basement conversion
Roughly $100,000-$200,000, depending on existing ceiling height and utility access
New detached ADU
Roughly $150,000-$280,000+ for a code-compliant, fully finished freestanding unit
System Development Charges (SDCs)
Approximately $7,000, recalculated at permitting and financeable through the city over up to 10 years
Pre-approved design plans
At least one design is free through the city's Pre-Approved ADU Program; additional architect-contributed designs are available for a set fee
These are general ranges from local contractor estimates and regional reporting, not quotes - actual cost depends on lot conditions, finishes, and whether utilities need to be extended. Eugene's relatively modest, financeable SDC compared with many Oregon cities is one of the more concrete cost advantages homeowners have here.
Before you apply
Tips for a smooth approval
Look at the Pre-Approved ADU Program before hiring an architect. It can save meaningful design time, and at least one plan is free.
Ask about financing your SDCs. Eugene lets you spread the roughly $7,000 charge over up to 10 years instead of paying it all at permitting.
Check whether your lot touches an alley. Detached ADUs skip the setback entirely along an alley-facing lot line, which can open up an otherwise tight lot.
Double-check the 10%-of-lot-area rule. On a small lot, that formula can cap your ADU well below the 800 sq ft maximum.
Plan your rental strategy before you build. If you want to short-term rent, only one unit on the property, not both, can operate as a short-term rental at a time.
FAQ
Common questions
Do I need to live on the property to build an ADU in Eugene?
No. Owner-occupancy of either the primary home or the ADU has not been required since Eugene's 2021 code update, and Oregon's HB 2001 bars owner-occupancy conditions statewide.
How many ADUs can I build on one lot in Eugene?
One ADU is allowed in addition to the primary dwelling.
Do I need extra parking for an ADU?
No additional off-street parking is required specifically for the ADU.
What's the maximum size for a detached ADU in Eugene?
800 sq ft or 10% of your lot area, whichever is smaller, with a 25 ft height limit (subject to a sloped-height rule near interior property lines).
How long does the permit process take?
Eugene reviews ADUs administratively as a building permit, with no public hearing. Timelines depend on application completeness and current workload - confirm current estimates with the Planning Division.
How much does an ADU cost to build in Eugene?
Garage conversions run roughly $70,000-$150,000, basement conversions roughly $100,000-$200,000, and new detached units roughly $150,000-$280,000+, based on local contractor estimates and regional reporting - not counting System Development Charges.
What are Eugene's System Development Charges for an ADU?
Approximately $7,000, recalculated at permitting and adjusted for inflation. Eugene allows homeowners to finance SDCs through the city over up to 10 years.
Does Eugene offer pre-approved ADU plans?
Yes, through the city's Pre-Approved ADU Program, which offers designs that have already cleared permit review, at least one available free of charge.
Can I rent my ADU out on Airbnb or a short-term rental platform?
Short-term rental of an ADU is allowed with annual city registration and a 30-day maximum stay, but you can't operate both the primary home and the ADU as short-term rentals at the same time. Confirm current rules with the city before you finalize plans.
