5 county-level rules, plus city-specific rules for 2 cities in Adams County, Colorado.
Verified from official government sources
Unincorporated Adams County permits one ADU per single-family home in any zone district. Minimum 500 sq ft; detached units cap at 1,500 sq ft, up to 25 ft tall. A building permit is required and the ADU cannot be sold separately.
Adams County DSR Sec. 4-03-03-02-01 (Accessory Dwelling Units)
The minimum size for any ADU is 500 square feet. Detached ADUs must be set back 10 feet behind the front structure line. ADUs can be up to 25 feet in height, measured to the roof mid-pitch.
Sheds and other accessory structures in unincorporated Adams County must sit at least 10 feet behind the home's front line and meet zone-district side and rear setbacks (10 feet in the A-3 zone). Maximum height for dwellings and accessory structures is 35 feet.
Adams County has no separate garage-conversion ordinance, but converting a garage into living space is a building-permit-required change. If it creates a second dwelling it must meet the county's ADU standards, and off-road parking still has to be provided.
A carport is an accessory structure in unincorporated Adams County and must meet the same setback and 35-foot height limits as other accessory buildings. On a manufactured-home lot, one garage or one attached carport is expressly allowed as an accessory use.
Adams County DSR Sec. 4-07-02-01-02-02(17)
Accessory uses for a manufactured home on an individual lot or parcel are subject to the accessory building setback requirements of the zone district in which it is located... and limited to the following: a. one (1) garage or one attached carport.
A single manufactured or tiny dwelling may serve as a single-family home on an individual lot in any residential zone that allows single-family homes, but it must be no more than 5 years old at siting, at least 864 sq ft, and installed on a permanent foundation.
Adams County DSR Sec. 4-07-02-01-02-02
At the time of siting, the unit is no more than five (5) years old. The unit is comprised of two (2) or more fully enclosed parallel sections not less than twelve (12) feet wide by thirty-six (36) feet long (producing a dwelling unit with a minimum of eight hundred sixty-four (864) square feet).
2 cities in Adams County have their own accessory structures rules. Each link goes to that city's dedicated page with code citations.
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