How long does it take to get an ADU permit approved in Colorado?
✓ Verified against code · August 19, 2026
Timelines vary, and some cities — Denver among them — publish no fixed day count at all. Where cities do publish targets, Lakewood is fastest: its administrative zoning review must be decided within 15 days of a complete application, though the building-permit step itself is separate and unpublished. Arvada targets about 3 weeks for a detached ADU and 1 to 2 weeks for an interior or attached one. Greeley publishes 20 working days for new construction and 10 for additions or remodels. Westminster's staff review can take up to 4 weeks.
Citation: varies by city — see city pages
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?
- Does Colorado allow two ADUs per lot?
- 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?
- 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.