Oregon · ADU Eligibility Checker

Oregon ADU Eligibility Checker

Oregon was the first US state to require statewide ADU approval — SB 1051 (2017) mandates at least one ADU per lot in cities over 2,500 population, and HB 2001 (2019) went further by eliminating off-street parking and owner-occupancy requirements. If you own a lot in an Oregon city, state law is on your side; the remaining work is checking local design standards and (for now) HOA CC&Rs.

Statewide ADU mandate
Yes (SB 1051)
Owner-occupancy required
No (HB 2001)
HOA override effective
2027 (HB 2138)

ADU Eligibility Checker

Find out if you can build an ADU on your property. Enter your details below for an instant assessment based on state and local regulations.

Property Details

6,000 sq ft
1,000 sq ft50,000 sq ft

Eligibility Assessment

Oregon · 6,000 sq ft lot · Single-Family zoning

Likely Eligible

Your property appears to meet state-level ADU requirements

Confidence:
medium — state-level data

Allowed ADU Types

Detached ADU
Attached ADU
Garage Conversion

Maximum ADU size: 900 sq ft

Key Rules & Restrictions

Maximum ADU size: 900 sq ft (or 50% of lot, whichever is less)

Oregon ADU Legislation

Key legislation: SB 1051 (2017), HB 2001 (2019)

  • •SB 1051 (2017) requires at least 1 ADU per lot in cities with population over 2,500
  • •HB 2001 (2019) eliminated owner-occupancy and parking requirements statewide
  • •2 ADUs per lot is a LOCAL ordinance decision (e.g., Portland Residential Infill Project), NOT statewide
  • •SB 391 (2021) allows rural ADUs on lots of 2+ acres only
  • •HB 2138 (2025) retroactively voids HOA restrictions effective January 1, 2027

Recommended Next Steps

1Verify eligibility with your local planning department — state rules are a floor, not a ceiling
2Get a preliminary site assessment from a licensed contractor
3Use our Cost Estimator to budget your project
4Explore financing options with our Financing Calculator

Important: This is general guidance based on state law. Local ordinances, overlay zones, and specific property conditions may affect eligibility. Always verify with your local planning department before starting any ADU project.

EstimateBuild CostCompareFinancing OptionsEstimateRental Income

How Oregon ADU Eligibility Works

Oregon's ADU framework is a layer cake. SB 1051 (2017) requires cities over 2,500 population to allow at least one ADU per single-family lot, setting the baseline state right to build. HB 2001 (2019) expanded that by eliminating off-street parking requirements for ADUs statewide and barring owner-occupancy mandates. Portland went further under its 2020 Residential Infill Project (RIP), allowing up to four units on a single residential lot in many zones and two ADUs on most single-family lots. SB 391 (2021) carved out a path for rural ADUs on lots of two acres or more outside urban growth boundaries. The calculator reads Oregon as green for almost any single-family configuration and green with an asterisk for multi-family, where local rules vary more.

The Portland-Versus-Rest-of-State Split

Oregon has one of the largest intra-state variances in the country on ADU rules because of Portland's additional allowances under RIP. In Portland, a standard-size single-family lot can host the primary dwelling plus two ADUs (one detached, one attached or conversion), totaling three units. In smaller Oregon cities — Salem, Eugene, Bend, Medford, Grants Pass, Ashland — the state floor of one ADU applies and additional units depend on local zoning. Rural parcels outside urban growth boundaries face a different regime under SB 391: allowed, but with a two-acre minimum and wildfire-hazard restrictions. The calculator approximates these by reading your zoning type, but the actual local rules are the authoritative source.

Where Eligibility Gets Complicated

A few Oregon-specific scenarios push the traffic light to yellow. First, Portland's historic districts and conservation districts require additional design review and can disallow specific ADU configurations (roof form, window placement, materials) even where the underlying zoning allows them. Second, the Oregon Statewide Planning Goals create some friction in coastal jurisdictions — the state's coastal zone has its own planning overlays that are not as aggressive as California's Coastal Commission review but do add a step. Third, steep slopes and flood hazard zones in the Portland West Hills and along the Willamette River limit buildable envelope in ways that can rule out detached ADUs on otherwise-eligible lots. Fourth, the HOA situation is transitional: HB 2138's HOA override doesn't take effect until January 1, 2027, so HOA-restricted lots are in a yellow-light state until then.

Disclaimer: Estimates on this page are based on state-level data and do not replace consultation with your local planning department, licensed contractor, or tax advisor. Verify rules and costs with local sources before starting any project.

Frequently Asked Questions

Does Portland still require owner-occupancy for JADUs?
No. HB 2001 (2019) eliminated owner-occupancy requirements statewide for all ADU types including internal conversions analogous to California's JADUs. Portland aligned its local code with state law. You can rent out both units on a single-family lot and live elsewhere.
My HOA's CC&Rs prohibit ADUs. Am I blocked?
For now, yes — HB 2138 (2025) voids HOA restrictions retroactively but only effective January 1, 2027. If your HOA is actively blocking and you're trying to build in 2026, you face either a negotiation with the HOA or a delay until the 2027 date. After January 1, 2027, CC&R language prohibiting ADUs becomes unenforceable and you have a clean path. Some HOAs have already amended their CC&Rs voluntarily; check whether yours is one of them.
Can I build two ADUs on my Portland lot?
Typically yes under the Residential Infill Project, though the exact maximum depends on your lot's zoning and whether it qualifies for the middle-housing allowances (triplex, fourplex, cottage clusters). A standard Portland single-family lot can usually host the primary dwelling plus two ADUs. Outside Portland, the state floor of one ADU applies unless the local city has its own additional allowance.
What are Oregon's maximum ADU size limits?
Cities can cap detached ADUs at 900 square feet under the state framework, though many cities (including Portland) allow larger. Attached ADUs are typically capped at 50% of the primary dwelling square footage, whichever is less. JADU equivalents (internal conversions) typically run 300–500 square feet. Check your local code — Oregon cities vary more here than California does.
I own a rural lot outside the urban growth boundary. Can I still build an ADU?
Under SB 391 (2021), yes, but with conditions: minimum two-acre lot size, primary dwelling must exist, wildfire hazard zone restrictions apply (ignition-resistant construction, defensible space), and the lot must not be in an exclusive farm-use or forest zone without an additional allowance. Rural ADUs are a newer and narrower path than urban ADUs in Oregon, and local counties implement SB 391 differently.

Other Oregon ADU Calculators

Cost Estimator — Oregon → Financing Calculator — Oregon → Rental Income Calculator — Oregon → Break-Even Calculator — Oregon → Property Value Impact — Oregon → ROI Calculator — Oregon → Permit Fee Calculator — Oregon →

Compare with Nearby States

ADU Eligibility Checker · WA → ADU Eligibility Checker · CA → ADU Eligibility Checker · CO →