County planners begin implementing state ADU law; staff seeks commission direction on affordability carve‑out

Coconino County staff told the Planning and Zoning Commission in a study session that the county must amend its zoning ordinance to comply with state law enacted as House Bill 2928 and asked whether commissioners want staff to pursue an optional local requirement to restrict one additional ADU as long‑term affordable housing.

What HB 2928 requires Jess McNeely, Community Development, summarized the statutory change: under HB 2928 every single‑family residential lot is entitled to two ADUs — one attached and one detached — both limited to a maximum of 1,000 square feet and the detached ADU may be up to 75 percent of the primary dwelling. For parcels of one acre or larger the statute allows a local jurisdiction to permit a third ADU (a second detached unit) and to require that third unit be deed‑restricted for long‑term affordable housing (defined in statute as renting to households at or below 80 percent of area median income).

Policy choices for the commission Staff presented the policy tradeoffs: restricting the optional third ADU to affordable housing could increase local long‑term rental supply and reduce the risk that new detached units become short‑term rentals. But enforcing an income restriction adds complexity: county staff flagged the need to verify household incomes for tenants over time and to record and monitor deed restrictions. Jess McNeely said Coconino County Health and Human Services was willing to perform income qualification for prospective tenants if the county adopted a deed‑restriction program, and that building‑permit reviewers would attach deed‑restriction documents to the permit record.

Other code changes Staff explained other required code updates: the state limits setback requirements — local jurisdictions cannot require a side setback greater than 5 feet for ADUs — and the county must revise its size and separation rules so ADUs of the permitted size can be built in practice without conflicting with septic and driveway constraints. Staff also noted wastewater/septic permitting limits ADU build‑out (permitting and site constraints could limit actual ADU construction on many one‑acre lots) and flagged a county‑city model plans program to offer inspected, preapproved ADU designs to reduce costs.

Next steps and schedule State law requires the county to adopt updates by the end of the calendar year; staff asked commissioners whether they want to provide direction at the next study session or wait until the October public hearing on the ordinance amendments. Vice Chair Paul Wilson said the issue is complex and asked for additional time; commissioners agreed to discuss further next month and to plan a public hearing in October so the Board of Supervisors can act by year end.

Provenance Topic intro: “...we let you know last month that, HB 29 28 was a, update state statute that is requiring updates to the county zoning ordinance regarding ADUs accessory dwelling units.” (transcript block_4187.3; excerpt length 178).

Topic finish: “Thank you. I think that's a great plan.” (transcript block_5086.935; excerpt length 30).