County study session reviews HB 2928 changes: more ADUs allowed, options to require affordable deed‑restriction

Coconino County planning staff briefed the Planning and Zoning Commission July 30 on changes required by state law HB 2928 to local zoning for accessory dwelling units (ADUs) and on options for how the county could implement the new rules.

Under the new statute, staff said, owners of single‑family residential lots will be entitled to two ADUs: at least one attached to the primary dwelling and one detached. Parcels of one acre or larger will be entitled to a third ADU (an additional detached unit). The state law also gives counties the option to require that the additional detached ADU on one‑acre‑plus parcels be deed‑restricted as affordable housing, defined in statute as units rented to households at or below 80 percent of area median income (AMI).

Planner Jess McNeely told commissioners that the county’s existing ordinance already allows one ADU by right, and previously required a deed restriction; that deed‑restriction requirement had been removed in a prior update. HB 2928 requires changes to the county ordinance, including a maximum ADU size allowance and setback limits. The statute sets a five‑foot maximum side‑setback requirement where a jurisdiction imposes setbacks on ADUs; it also changes the allowable ADU size to up to 75 percent of the primary dwelling (still capped at 1,000 square feet).

Pros and cons discussed: Commissioners and staff discussed the benefits of requiring an affordability deed restriction on the third ADU on one‑acre parcels: it could expand locally accessible housing and would prevent that unit from operating as a short‑term rental. Staff cautioned that administering ongoing income verification and deed restrictions would be more complex and would require coordination with Health & Human Services, which staff said would be willing to income‑qualify tenants. Staff noted wastewater/permitting, septic capacity and setbacks as practical constraints that will limit take‑up of additional ADUs in many parts of the county.

Timing and next steps: State statute requires that the county adopt ordinance changes by the end of the calendar year; staff told commissioners they plan to return with an ordinance draft at the commission’s October public hearing, to allow Board of Supervisors action before year end. Several commissioners asked for more time to consider the affordable‑housing‑deed restriction option; staff said the commission will discuss the issue again at the August study session and at the October hearing.

Quotation: McNeely summarized the choice facing the county: "This is our option—to make that second detached ADU restricted to affordable housing," he said, explaining the tradeoffs between increasing affordable rental stock and the administrative burden of enforcing deed restrictions and income verification.

Context: ADU policy is a county and statewide tool to increase housing supply. Commissioners noted competing interests: expanding affordable units versus the administrative cost and homeowner burdens of income‑restricted units. Staff said they are exploring incentives, model plans and a coordinated program with the City of Flagstaff to offer pre‑approved sustainable ADU plans to reduce design costs and speed permitting.