ADU rules for Seneca
Accessory Dwelling Unit (ADU) Rules for Seneca, OR
Is your property eligible for an ADU?
# of Properties
220
Owner-occupied
33%
Zoning districts
4
Avg Home Value
$85,331
Median Lot Size
0.21 acres
Avg Income
$81,136
Residential Types:
220 housing units
Other
100%
Zoning Districts:
236 parcels · 4 districts
R-1
75%(177)
M-1
15%(35)
C-1
9%(21)
PR-1
1%(3)
ADU Rules
What can you build in Seneca, OR?
Seneca, OR follows state and local rules for Accessory Dwelling Units. Here is a concise overview of the local rules.
Eligibility
- –Internal / Attached ADU: Not addressed in the local bylaw
- –Detached ADU: Not addressed in the local bylaw
Parking
- –1 space per ADU; max: none; general rules: off-street parking on the same parcel with the dwelling; sum parking for multiple uses; joint use allowed if hours do not overlap with recorded agreements
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.
Grant County