ADUs are allowed in Unincorporated BentonTypes:DetachedInternal
Types:DetachedInternal
Accessory Dwelling Unit (ADU) Rules for Unincorporated Benton, OR
Is your property eligible for an ADU?
# of Parcels
12,015
Zoning districts
32
Zoning Districts:
12,027 parcels · 32 districts
EFU
27%(3,230)
RR-2
25%(3,029)
FC
18%(2,217)
UR-5
9%(1,139)
Other
20%(2,412)
ADU Rules
What can you build in Unincorporated Benton, OR?
Unincorporated Benton, OR follows state and local rules for Accessory Dwelling Units. Here is a concise overview of the local rules.
Eligibility
- –Internal / Attached ADU: By Right
- –Detached ADU: By Right
Interior / Attached ADU Size Limits
- –Maximum of 900 sq ft of habitable space for an internal or attached ADU; a single-car garage up to 300 sq ft is excluded from this cap.
Detached ADU Size Limits
- –Maximum detached ADU size of 900 sq ft of habitable space; a single-car garage up to 300 sq ft is excluded from this cap.
Owner Occupancy
- –No owner-occupancy requirement
Parking
- –0 spaces; ADUs exempt from the 2-space minimum; if off-street parking is provided, apply general standards and share driveway access with the primary dwelling.
Rental Restrictions
- –Short-term rentals (<1 month) prohibited for ADUs
ADU State Law
What can you build in Oregon?
- –In urban growth areas, Oregon law requires cities and counties to allow at least one ADU on lots zoned for detached single-family homes.
- –Local jurisdictions cannot require owner occupancy for ADUs, but may regulate short-term or vacation rentals.
- –There are no statewide limits on ADU size, height, setbacks, lot size, or floor area ratio. Local zoning rules apply.
- –Parking requirements, if any, are set by the local jurisdiction, subject to state limitations.
- –Some cities may allow more than one ADU per lot, depending on local code.
- –Oregon law does not require counties to allow ADUs in rural residential zones. Whether an ADU is allowed depends on county zoning.
- –ADUs in rural residential areas cannot be used for short-term or vacation rentals.
- –Additional requirements may apply related to wildfire risk, water supply, septic capacity, and fire access.
- –Counties may impose additional restrictions beyond state law or choose not to allow ADUs at all.
- –If a county allows ADUs, state law imposes strict limits, including a minimum 2-acre lot size, a maximum ADU size of 900 sq ft, a location within 100 ft of the primary dwelling, and a limit of one ADU per parcel.
What's allowed on your lot?
These are the municipality-wide rules. What's allowed on a specific property also depends on state laws, setbacks, floor area ratio, lot coverage, environmental constraints, topography, and other property-specific factors. Search your address on FutureLot to see what's allowed on your property.
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ADU rules in other Oregon municipalities
Rules change at the town line. Check the municipality your property is actually in.
Benton County