Board discusses state bill HB 29‑28 requiring more accessory dwelling units; supervisors favor deed‑restriction option for one unit

The Coconino County Board of Supervisors heard a briefing on Arizona House Bill 29‑28 during the Oct. 1 work session and discussed how the county will implement the new state requirement to allow additional accessory dwelling units (ADUs) in residential zoning.

What the law requires and staff explanation Community Development staff told the board that HB 29‑28, enacted in May, requires counties to permit additional ADUs in single‑family residential zones: at least two ADUs (one attached and one detached) on any residential parcel, and on parcels 1 acre or larger the county must allow an additional (third) ADU (detached). "HB 29 28, approved this past May, down in Downstate Capitol," said Jess McNeely, new development staff, explaining the timetable and the county’s obligation to update its zoning ordinance "no later than the end of the calendar year."

County options and administration The state law allows counties to require, by local rule, that the additional detached ADU (the third unit on parcels of 1 acre or larger) be deed‑restricted for affordable housing. The statute defines the affordability requirement (household at or below 80% of area median income and rent no more than 30% of gross income). Staff described how the county could administer the deed‑restriction option and the practical implications: income verification would likely be handled by Health and Human Services (HHS), building permits would be linked to recorded deed restrictions, and short‑term rental permits would not be allowed for a unit deed‑restricted as affordable.

Pros and cons discussed Supporters on the board and several planning commissioners argued the deed‑restriction option offers a new tool to create affordable housing and to reduce short‑term rental conversion of units. They noted the county would be able to try the program, evaluate results and remove the deed‑restriction requirement later if necessary. Vice Chair Jeronimo Vasquez, Chair Patrice Horstman and several supervisors expressed support for pursuing the deed‑restriction option now, citing housing shortages and short‑term rental pressure.

Concerns raised by planning commissioners and supervisors Some planning commissioners and trustees cautioned that requiring a deed‑restricted third ADU could reduce property‑owner flexibility and discourage construction of the third ADU, thereby limiting overall housing supply. Staff acknowledged the added administrative workload — building permitting, deed‑restriction recording and coordination with HHS for income verification — but said it is manageable with existing staff and interdepartmental cooperation.

Board guidance Supervisors said the statute’s January 1 timeline for adoption meant the county had a one‑time opportunity to adopt the deed‑restriction option; if the board does not adopt it before that deadline, the county would lose the authority to require affordability on that unit later. Several supervisors said they favored adopting the deed‑restriction option now and testing its effect, then revisiting the rule if it significantly constrained housing supply.

Technical details discussed Staff said setbacks for ADUs are defined by the statute and counties must allow certain reduced interior side setbacks (as low as 5 feet) for ADUs. Size limits mirror state language (no greater than 75% of the primary residence and not to exceed 1,000 square feet). Water and wastewater requirements — as with any new home or unit — remain applicable and must be met in any location.

Next steps Staff said the item will go to the Planning and Zoning Commission for a recommendation, then return to the board in a public hearing. The commission is scheduled to consider recommended zoning ordinance amendments later in October and deliver a recommendation to the board. If the board confirms direction, staff will prepare ordinance language for adoption before the statutory deadline.

Quote from staff "We are required to update the zoning ordinance no later than the end of the calendar year," Jess McNeely said, describing the statutory timing and the options available to the county.

Why this matters If the board adopts the deed‑restriction option for the third ADU on parcels of 1 acre or larger, the county could add income‑restricted rental units while also limiting short‑term rental eligibility for those units. The board majority signaled support to attempt an initial regulatory approach and to monitor administrative impacts and housing supply effects.