ADUs are allowed in Unincorporated LarimerTypes:DetachedInternal
Types:DetachedInternal
Accessory Dwelling Unit (ADU) Rules for Unincorporated Larimer, CO
Is your property eligible for an ADU?
# of Properties
34,290
Owner-occupied
61%
Zoning districts
156
Median Lot Size
1.34 acres
Avg Income
$112,523
Residential Types:
34,290 housing units
Other
100%
Zoning Districts:
53,153 parcels · 156 districts
O
36%(18,949)
RR2
25%(13,407)
MHP
8%(4,235)
UR1
5%(2,634)
Other
26%(13,928)
ADU Rules
What can you build in Unincorporated Larimer, CO?
Unincorporated Larimer, 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 is the minimum of: the lot-size cap (900 sq ft ≤15,000 sq ft; 1,000 sq ft for 15,001–100,000 sq ft; 1,200 sq ft >100,000 sq ft), 75% of the principal dwelling’s floor area excluding basements (but not forced below 750 sq ft solely by that 75% limit), and the size of the principal dwelling itself.
Detached ADU Size Limits
- –Maximum based on 75% of the primary dwelling’s floor area excluding basement, but never less than 750 sq ft and never more than the principal dwelling’s size.
- –Maximum size by lot area: 900 sq ft for lots up to 15,000 sq ft; 1,000 sq ft for 15,001–100,000 sq ft; 1,200 sq ft for more than 100,000 sq ft.
Max Units
- –Single-family detached: 1 ADU/lot
- –Business ADU (nonresidential lots): 1/lot
- –Farmsteads: 1 per 40 ac, max 3
Owner Occupancy
- –Owner occupancy is not required for the principal or ADU.
Parking
- –Residential ADU: no min or max parking specified; Business ADU: 1 space ≤800 sq ft, 2 spaces >800 sq ft, in addition to principal-use parking; no ADU-specific parking in the general table.
Rental Restrictions
- –Short-term rentals (<30 days) prohibited; lodging facilities not allowed in the ADU
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.
Larimer County
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