Aurora, CO Accessory Structures: ADU Permits (2026)

Aurora's current ADU rule sits in UDO 146-3.3.6 under Dwelling Unit, Detached Accessory. The code allows one ADU on a lot that contains and is accessory to a single-family dwelling, requires the ADU to be detached (no garage conversion of attached units), caps height at 24 feet regardless of the primary structure height, and applies standard accessory-structure setbacks (5 feet side and rear for structures over 120 sq ft per UDO 146-4.2.3). Second-story window placement must preserve neighbor privacy. Plans are submitted to the Aurora Building Division at 15151 E. Alameda Parkway through the online permit portal. Standard review takes 4-6 weeks for a first round; the package needs a site plan, floor plans, elevations, energy compliance to the 2021 IECC as adopted in Aurora City Code Chapter 22, and Aurora Water service confirmation. Colorado HB24-1152 (signed 2024, operative June 30, 2025) requires Aurora as a subject jurisdiction inside the DRCOG MPO to allow at least one ADU on every single-family lot through an administrative-only process and bars owner-occupancy mandates and parking minimums on ADUs. Aurora is amending the UDO to comply; until adoption the city continues to apply the existing 146-3.3.6 rules to the extent they do not conflict.