ADU rules in Colorado
Representative cities: Denver, Colorado Springs.
ADU permit rule
Permit requiredCase by casecity authority
Fee basis
Valuation-based; set by the issuing city/county.
Typical timeline
Varies
Setback
—
Area threshold
Not size-exempt
Exempt if
None — an ADU always requires a building permit where local zoning allows it.
Go / no-go
case-by-case
Colorado is a home-rule state with no mandatory statewide residential code, so ADU rules vary by jurisdiction. Denver allows ADUs by right through its e-permits process; other cities/counties differ. When permitted by zoning, a full building permit is required.
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Frequently asked questions
Do I need a permit to build an ADU in Colorado?
Per Colorado rules, an ADU is "yes" for a permit and the authority is "city". Colorado is a home-rule state with no mandatory statewide residential code, so ADU rules vary by jurisdiction. Denver allows ADUs by right through its e-permits process; other cities/counties differ. When permitted by zoning, a full building permit is required. Always confirm with the issuing building department.
How big can an ADU be in Colorado?
Size limits for an ADU in Colorado are set by local zoning — verify with your city building department.
What are the ADU setbacks in Colorado?
Setback rules vary by city in Colorado; confirm with the local planning or building department.
How much does an ADU permit cost in Colorado?
Fee basis: Valuation-based; set by the issuing city/county.