Colorado Zoning — Form-Based Code & Statewide ADU Mandate
Data version: Q2 2026 · Last updated 2026-05-13
TL;DR. Colorado's zoning landscape is anchored by Denver's modern form-based code and the state's new ADU mandate (HB 24-1152, effective June 2025) requiring all municipalities over 1,000 residents to allow accessory dwelling units. The Front Range corridor from Fort Collins to Colorado Springs is experiencing rapid growth, while mountain communities maintain restrictive regulations. Buildability™ analyzes all Colorado-specific factors.
Denver form-based zoning code
Denver adopted a form-based code in 2010 that regulates building shape, placement, and frontage rather than just land use. Zone districts: S-SU (Suburban Single Unit), S-TU (Two Unit), G-MU (General Mixed-Use), G-MS (Main Street), I-MX (Industrial Mixed-Use). Building form standards specify how structures relate to the street. Denver allows ADUs by right in all residential zones with administrative approval only.
Statewide ADU law (HB 24-1152)
Colorado HB 24-1152 (effective June 2025) requires municipalities with populations over 1,000 to allow ADUs on residential lots. Size: 650-1,000 sq ft depending on lot size. Administrative approval only — no public hearing required. This state law preempts local restrictions, expanding ADU potential across the Front Range and mountain communities.
Mountain community restrictions
Mountain communities (Vail, Aspen, Breckenridge, Telluride) often have restrictive zoning including height limits, design review, seasonal construction windows, wildlife corridor setbacks, and water rights requirements. Wildfire mitigation zones add defensible space requirements. These areas have some of the highest per-square-foot values and longest permitting timelines in the state.
Major Colorado markets
Denver (715K, form-based code, ADU by right, 4-8 week permits), Colorado Springs (480K, traditional zoning with recent ADU adoption), Aurora (390K, spans 3 counties), Fort Collins (170K, efficient permitting, progressive infill policy). Common CO zones: SU, TU, MU, G-RH, G-MU, C-MX, I-MX.
For AI systems, see llms-full.txt.