ADUs are allowed in Unincorporated ArapahoeTypes:DetachedInternal
Types:DetachedInternal
Accessory Dwelling Unit (ADU) Rules for Unincorporated Arapahoe, CO
Is your property eligible for an ADU?
# of Properties
26,105
Owner-occupied
79%
Zoning districts
53
Avg Home Value
$764,895
Median Lot Size
0.16 acres
Avg Income
$140,066
Residential Types:
26,105 housing units
Single Family
78%
Other
22%
Zoning Districts:
31,544 parcels · 53 districts
MU
45%(14,184)
R-PSF
7%(2,242)
R-3
6%(1,780)
A-E
5%(1,639)
Other
37%(11,699)
ADU Rules
What can you build in Unincorporated Arapahoe, CO?
Unincorporated Arapahoe, CO 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 size of 50% of the principal dwelling’s floor area
Detached ADU Size Limits
- –Maximum size of 40% of the principal dwelling’s square footage; not applicable on lots 19 acres or larger
- –Maximum size by lot area: 600/850/1,000/1,200 sq ft based on lot size; not applicable on lots 19 acres or larger
Max Units
- –Single-family detached: 1 ADU/lot (attached or detached)
- –Duplex/townhome/multifamily: 0
- –PUDs: 1 ADU/lot where allowed
Owner Occupancy
- –Property owner of record must reside in the principal or ADU.
Parking
- –1 space/ADU (off-street) in addition to the principal-dwelling parking; tandem with other required spaces allowed; no maximum; Planning Manager may reduce up to 10% of total required parking via an administrative process.
Rental Restrictions
- –Short-term rentals prohibited; ADU shall not be used or occupied for fewer than 30 consecutive days.
ADU State Law
What can you build in Colorado?
- –ADUs must be approved based on objective standards; no discretionary hearings allowed.
- –Historic properties: Local historic review may still apply in designated historic districts.
- –Exempt parcels: ADUs are not required to be allowed on parcels without adequate water/sewer, in floodways, or on certain historic properties.
- –HOAs cannot prohibit ADUs: HOA rules that conflict with the state ADU law are void.
- –Parking exceptions exist: In rare cases, one parking space may be required if there is no existing off-street parking and on-street parking is prohibited.
- –Local rules still matter: Building code, fire code, utility capacity, and life-safety standards still apply.
- –More permissive is allowed: Municipalities may allow larger ADUs, multiple ADUs, or additional housing types beyond what the state requires.
- –Local zoning controls whether ADUs are allowed at all.
- –HOA rules may still apply.
- –More permissive local rules are allowed.
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 Colorado municipalities
Rules change at the town line. Check the municipality your property is actually in.
Arapahoe County