Colorado · CO
ADU laws & builders in Colorado
Colorado HB24-1152 (2024) requires major cities to allow ADUs. Denver and Boulder are leading the state with city-specific ADU programs, and Front Range builder activity is growing fast as homeowners take advantage of the new rules.
Last reviewed: 2026-05-29
Are ADUs legal in Colorado?
Increasingly, yes. Colorado's HB24-1152 (2024) requires many larger municipalities — especially along the Front Range — to allow ADUs on single-family lots and removes some of the local barriers that blocked them. Denver and Boulder already have established ADU programs, and other cities are updating their codes to comply.
Key rules that affect your build
Because HB24-1152 is recent, cities are still adopting compliant zoning. That means the specific allowances — size, setbacks, parking, and whether your city offers pre-approved plans yet — vary a lot by jurisdiction right now. Denver and Boulder are the most builder-ready today.
Cost and timeline in Colorado
A permitted detached ADU on the Front Range generally runs $190K–$400K turnkey, with modular/prefab options (Colorado has several) often coming in lower. Plan on 8–13 months. Local builder knowledge matters here more than usual because the rules are actively changing.
Official source
We summarize Colorado's ADU rules in plain English. For the authoritative, always-current legal detail, go straight to the source:
Colorado DOLA — Accessory Dwelling UnitsAlways verify current rules with the official source before making decisions.
Pre-approved ADU plan programs in Colorado
- Denver — Denver ADU Permitting
- Boulder — Boulder ADU Program
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