Commerce City, CO Accessory Structures: ADU Rules (2026)

The Land Development Code defines Dwelling, Accessory in Sec. 21-11200 as a second dwelling unit, either built inside or added onto an existing single-family detached home or in a separate accessory structure on the same lot, with its own kitchen, bathroom, and sleeping space functioning as a complete, independent living facility. Rather than listing ADUs as a right-by-permit use across every district the way it does storage sheds or detached garages, the Bulk Standards for Accessory Structures and Uses table in Sec. 21-5450 handles a Guesthouse/Carriage House by pointing applicants to the zone district or PUD Zone Document where allowed, meaning the underlying zone district regulations or an approved Planned Unit Development document control whether an ADU is permitted on a given lot and what size, setback, and design standards apply.

Where a district or PUD document does allow one, Sec. 21-5420(2) singles out an ADU as the one place a residential accessory structure can be used commercially: it may host a short-term rental, the only commercial use a residential accessory structure is allowed to carry. That short-term rental, governed separately by Sec. 21-5263, still needs its own city license under Chapter 9 of the Municipal Code, cannot host guests longer than 30 consecutive days, and cannot sit within 500 feet of another licensed short-term rental in the same residential zone.

Sec. 21-5263(6) also blocks an owner from running the short-term rental in the main house while treating the ADU as a primary residence; the principal dwelling must stay a long-term residence whenever it isn't being rented out.