Littleton, CO Accessory Structures: ADU Rental Restrictions (2026)

Section 3-23-10(a)(3) addresses parcels that contain an accessory dwelling unit and sets a firm line between attached and detached ADUs. Where the property owner also lives in the main residence, the owner can obtain a short-term primary-rental license, but only for the main residence itself, not the ADU. The subsection then flatly states that short-term rentals are not permitted in ADUs that are detached, whether the detached unit would operate as the primary dwelling or as a non-primary rental, and that only attached ADUs are allowed to be used as applicable.

In practice, that means an owner with a detached backyard cottage or carriage house cannot license that structure for short-term rental use under Chapter 23 at all, no matter which unit on the lot is the owner's primary residence. An attached ADU sharing a wall or roofline with the main house does not carry the same categorical bar, though it still has to satisfy the chapter's other conditions, including the primary-residence rule in Section 3-23-7(a) and the safety and insurance requirements in Sections 3-23-5 and 3-23-9.

The restriction sits alongside the City's adopted residential building code amendment requiring interconnected smoke and carbon monoxide alarms between an attached ADU and the primary dwelling, which applies where an attached ADU shares the fire-separation exception in the code.