ADUs are allowed in AspenTypes:DetachedInternal
Types:DetachedInternal
Accessory Dwelling Unit (ADU) Rules for Aspen, CO
Is your property eligible for an ADU?
# of Properties
6,389
Owner-occupied
22%
Zoning districts
27
Avg Home Value
$6,023,252
Median Lot Size
0.02 acres
Avg Income
$87,483
Residential Types:
6,389 housing units
Single Family
26%
2-3 Family
8%
Apts (4+ units)
8%
Other
57%
Zoning Districts:
9,345 parcels · 27 districts
R/MF
17%(1,599)
R-15
12%(1,140)
L
11%(991)
R-6
10%(949)
Other
50%(4,666)
ADU Rules
What can you build in Aspen, CO?
Aspen, 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 800 sq ft of net livable area for internal or attached ADUs
Detached ADU Size Limits
- –Maximum size of 800 sq ft (net livable area) for a detached ADU (backyard cottage)
Max Units
- –1 total per primary residence: 1 ADU or 1 carriage house
Owner Occupancy
- –ADUs must be occupied by a local working resident.
Parking
- –1 space/ADU on-site; max 1.25 spaces; not tandem with the primary residence; on-site only (no cash-in-lieu or mobility substitutions); reductions/variations via Special Review under the ADU chapter.
Rental Restrictions
- –Short-term rentals prohibited; 6+ month leases required; leases must be recorded with APCHA.
- –ADUs may be rented only to local working residents; non-local tenants are not allowed.
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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Is your property eligible for an ADU?
ADU rules in other Colorado municipalities
Rules change at the town line. Check the municipality your property is actually in.
Pitkin County