Grand Junction ADU Zoning Rules & Permit Guide

ADU Regulations in Grand Junction, Colorado

Updated September 29, 2026

In Mesa County on Colorado's Western Slope, Grand Junction allows ADUs in lower-density single-family zones. Without a Colorado state ADU mandate, the city's 25% lot coverage limit and owner occupancy requirement are locally determined.

Below is a summary of the key zoning rules applicable to Accessory Dwelling Units in Grand Junction as of 2026. Regulations are governed by local zoning ordinances, as Colorado has no statewide ADU mandate (HB 24-1152 addresses transit density).

Additional Local Requirements for Grand Junction

• ADU in lower-density single-family zones
• Minimum 200 sq ft
• Maximum 25% lot coverage
• Building permit required
• ⚠️ CO has NO statewide ADU mandate — verify with city

Frequently Asked Questions About ADUs in Grand Junction

Can I build an ADU in Grand Junction?

Grand Junction allows ADUs in single-family zones. Owner occupancy and off-street parking must be provided.

What is the maximum ADU size allowed in Grand Junction?

ADUs in Grand Junction can be up to 1,000 square feet, subject to the property's zoning and lot coverage limits. Always confirm the exact allowed size with the Grand Junction planning department before designing your project.

What are the setback requirements for an ADU in Grand Junction?

ADUs in Grand Junction generally require setbacks of 5 ft rear, 5 ft side. Colorado has no statewide ADU mandate, so the exact setback figures come from Grand Junction's own zoning code — confirm them with the city planning department before you design.