State Preemption of Local Zoning in Colorado
How Colorado state law overrides local zoning ordinances. ADU preemption, lot split preemption, and impact on city-level regulations.
What Is State Preemption?
State preemption occurs when a state law overrides local government ordinances in a specific area. In land use, preemption means a city or county cannot adopt zoning rules that are more restrictive than the state standard. If a city tries to prohibit something the state law permits, the state law wins.
Colorado actively uses preemption in housing law. The state has enacted legislation that prohibits local governments from blocking certain types of housing development — most notably accessory dwelling units (ADUs) and lot splits.
ADU Preemption
Colorado House Bill 24-1175 — Accessory Dwelling Unit Zoning
This law preempts local ordinances — cities cannot impose rules stricter than the state ADU standard. Effective 2024-08-07.
What local governments cannot restrict:
- Requires all Colorado municipalities with population over 1,000 to allow at least one ADU per single-family residential lot by-right
- Prohibits minimum lot size requirements specifically targeting ADU prohibition — local minimum lot size cannot exceed the zone's standard minimum
- Requires ministerial (administrative) ADU approval — no discretionary design review for ADUs meeting objective standards
- Creates a state enforcement mechanism through the Colorado Department of Local Affairs (DOLA)
How Preemption Affects Colorado Cities
State preemption applies to every incorporated city and unincorporated area in Colorado. Select a city below to see how state preemption interacts with local zoning rules.
Source: Colorado House Bill 24-1175 — Accessory Dwelling Unit Zoning. Last verified April 5, 2026. View source