5 county-level rules, plus city-specific rules for 2 cities in Larimer County, Colorado.
Verified from official government sources
Unincorporated Larimer County allows one Accessory Living Area per lot as a use by right. Since June 30, 2025 (HB24-1152) no planning review is needed before applying for the building permit. Size is capped by lot size under Table 3-15.
Larimer County Land Use Code §3.4.5.A
With the passage of Colorado House Bill 24-1152, which goes into effect June 30, 2025, Larimer County no longer requires applicants to go through a planning process before applying for an Accessory Living Area building permit. One accessory living area is permitted per lot.
In unincorporated Larimer County, a one-story storage shed under 200 sq ft with no utilities needs no building permit, but it must still meet Land Use Code setbacks, floodplain and lot-coverage rules. Bigger sheds or any with utilities need a permit.
Larimer County Building Division - Detached Structures
No Building Permit is Required When All of the Following Apply... The structure is a one-story, detached accessory structure used as a tool or storage shed, playhouse or similar use. The floor area does not exceed 200 sq. ft. There are no utilities added... The maximum eave height is 10 feet.
Converting a garage into habitable or separate living space in unincorporated Larimer County requires a building permit and must meet building-code habitability standards. If it becomes a separate unit it is treated as an Accessory Living Area under Land Use Code §3.4.5.
A carport is a detached or attached accessory structure. In unincorporated Larimer County a permit is required once it exceeds 200 sq ft, is attached, or adds utilities. All carports must meet Land Use Code setbacks and lot-coverage limits.
Larimer County Building Division - Detached Structures
A Building Permit is Required When Any of the Following Apply... The structure exceeds 200 sq. ft. in floor area or is greater than one story in height... A detached structure within 6' of a residential building, or within 3' of a property line, including overhangs, requires fire-rated construction.
By Colorado law a tiny house is 400 sq ft or less (excluding lofts). In unincorporated Larimer County, a tiny house on a permanent foundation is a legal dwelling with a building permit; a tiny house on wheels is treated as an RV and cannot be a year-round home.
Larimer County Community Development - Tiny Houses (HB22-1242; 2021 IRC App. Q)
By Colorado law and building code rules, Tiny Houses are 400 sq. ft. in floor area or less, excluding lofts... A 'Tiny House on Wheels' (THOW) is still considered a Recreational Vehicle (RV) and is regulated by the Land Use Code (LUC) instead of the building code... They are not considered permanent homes and cannot be occupied year-round.
2 cities in Larimer County have their own accessory structures rules. Each link goes to that city's dedicated page with code citations.
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