ADUs are allowed in SilverthorneTypes:DetachedInternal
Types:DetachedInternal
Accessory Dwelling Unit (ADU) Rules for Silverthorne, CO
Is your property eligible for an ADU?
# of Parcels
3,562
Zoning districts
11
Avg Parcel Value
$1,348,694
Median Parcel Size
0.21 acres
Zoning Districts:
3,562 parcels · 11 districts
PUD
56%(1,978)
R6
14%(481)
RF
10%(364)
R15
7%(260)
Other
13%(479)
ADU Rules
What can you build in Silverthorne, CO?
Silverthorne, 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 33% of the single-family dwelling’s floor area (attached garage may be included; detached garage may not).
Detached ADU Size Limits
- –Maximum ADU size is 33% of the floor area of the single-family home (attached garage may be counted; detached garage may not).
Max Units
- –Single-family: 1 ADU per lot.
- –Duplex/multifamily: none specified.
Owner Occupancy
- –Owner must occupy primary residence or ADU
Parking
- –No numeric ADU parking min/max; must show evidence of sufficient off-street parking for both the primary dwelling and the ADU; all required residential parking on the same lot; if a use is not listed, the Community Development Director applies the most restrictive standard.
Rental Restrictions
- –Short-term rentals prohibited for properties with a single apartment; minimum lease term is 6 months.
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.
Summit County