Accessory Structures in Pitkin County, CO (2026)

ADU Rules

Pitkin County does not use the term 'ADU' as a primary regulatory category. Instead, the Pitkin County Land Use Code (LUC) recognizes Caretaker Dwelling Units (CDUs) and Employee Dwelling Units (EDUs), both of which are deed-restricted accessory dwellings tied to local-employee occupancy under the Aspen/Pitkin County Housing Authority (APCHA) framework. A CDU is a permitted accessory use in most rural and residential zones (RS-160, RS-35, RS-30, RS-20, AR-10, AR-2, R-30, R-15, R-15A, R-6) when attached to a single-family principal dwelling and the lot meets the minimum lot area for one dwelling unit in that zone (LUC Sec. 4-30-50(e)(1)). Detached CDUs and CDUs on substandard lots require Special Review (LUC Sec. 4-30-50(e)(2)). Maximum size is 1,000 net livable square feet on lots 30,000 sq ft or larger and 700 net livable square feet on lots smaller than 30,000 sq ft. The CDU floor area counts against the parcel's total allowed floor area. A deed restriction must be recorded limiting occupancy to no more than two adults plus related children who qualify as community employees under APCHA guidelines, or members of the owner's immediate family, with rentals (if rented) of at least six months. EDUs are a separate category up to 1,500 net livable square feet, also deed-restricted to APCHA-qualified residents under LUC Sec. 6-30-40(d). HB24-1152 (Colorado's 2024 statewide ADU mandate) does not apply: Pitkin County and the City of Aspen are not within any of Colorado's five MPOs (DRCOG, NFRMPO, PPACG, GVMPO, PACOG), so the county is not a 'subject jurisdiction' and retains full discretion over accessory dwelling rules under CRS Title 30 county powers.