ADUs are allowed in HermistonTypes:DetachedInternal
Types:DetachedInternal
Accessory Dwelling Unit (ADU) Rules for Hermiston, OR
Is your property eligible for an ADU?
# of Properties
6,708
Owner-occupied
57%
Zoning districts
14
Avg Home Value
$364,327
Median Lot Size
0.20 acres
Avg Income
$70,233
Residential Types:
6,708 housing units
Single Family
5%
2-3 Family
4%
Apts (4+ units)
2%
Other
89%
Zoning Districts:
8,048 parcels · 14 districts
R-3
25%(2,050)
R-1
22%(1,747)
R-2
20%(1,634)
R-4
18%(1,443)
Other
15%(1,174)
ADU Rules
What can you build in Hermiston, OR?
Hermiston, 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
Max Units
- –1 ADU per lot for single-family dwelling lots (detached, attached, or interior). Not permitted on lots without a single-family dwelling.
Parking
- –No ADU-specific min/max; comply with general off-street parking standards (§§157.175–157.179); Uses & Spaces has no ADU entry; unlisted uses determined by Planning Commission (§157.178(B)); spaces must be on the same lot and meet design standards (§157.179(E)).
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.
Umatilla County