Flagstaff ADU Zoning Rules & Permit Guide

ADU Regulations in Flagstaff, Arizona

Updated September 29, 2026

At 7,000 feet in Coconino County, Flagstaff permits ADUs under local ordinance with a focus on rental housing affordability. The mountain climate influences building standards for accessory units.

Below is a summary of the key zoning rules applicable to Accessory Dwelling Units in Flagstaff as of 2026. Regulations are governed by local zoning ordinances, as Arizona has no statewide ADU mandate.

Additional Local Requirements for Flagstaff

• ADU allowed in residential zones per local ordinance
• Minimum 200 sq ft
• Building permit required
• ⚠️ AZ has NO statewide ADU law — city code governs

Frequently Asked Questions About ADUs in Flagstaff

Can I build an ADU in Flagstaff?

This Arizona city permits ADUs under local ordinance. Confirm your zone's eligibility with the planning department first.

What is the maximum ADU size allowed in Flagstaff?

ADUs in Flagstaff 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 Flagstaff planning department before designing your project.

What are the setback requirements for an ADU in Flagstaff?

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