Does Colorado allow two ADUs per lot?
✓ Verified against code · August 19, 2026
No — Colorado's HB24-1152 requires cities to allow one ADU per lot, not two. That is a deliberate contrast with Washington's HB 1337, which requires cities over 25,000 people to allow two ADUs per residential lot. Colorado's floor is administrative approval of a single accessory unit — attached, detached, or interior — wherever a single-family home is allowed, in cities and towns of 1,000-plus residents inside a metropolitan planning organization. City codes across the state reflect that one-per-lot baseline, from Arvada's and Boulder's explicit 'one ADU per lot' language to Denver's 'one per zone lot' rule.
Citation: C.R.S. 29-35-403(1)
How current is this?
Colorado’s ADU rules run under HB24-1152 (2024). HB24-1152 (codified at C.R.S. 29-35-401 through 29-35-405) required every Colorado city or town of 1,000+ residents inside a metropolitan planning organization to allow one ADU wherever a single-family home is allowed, through administrative approval, by June 30, 2025 — banning ongoing owner-occupancy mandates (an at-application residency check is allowed), most new-parking requirements, and design standards that would block an ADU in the 500–750 sq ft range. Note the contrast with Washington: one ADU per lot, not two. We verified this answer against primary sources on August 19, 2026, and every change we catch is logged in the changelog.
More Colorado ADU questions
- What is HB24-1152?
- Which Colorado cities are not complying with the ADU law?
- What happened to Lakewood's zoning code?
- How big can an ADU be in Colorado?
- What is the 500 to 750 square foot size protection in Colorado's ADU law?
- Do Colorado cities require ADU owners to live on the property?
- Can Colorado cities require parking for an ADU?
- What does home rule mean for Colorado's ADU law?
- What do Colorado ADU permits cost?
- How long does it take to get an ADU permit approved in Colorado?
- Can I rent out my Colorado ADU short-term on Airbnb?
Not legal advice — local ordinances can go further than the state floor. The citation above points at the governing statute; check your city’s code for the specifics.