Senate approves statewide accessory-dwelling-unit provisions with exceptions for historic districts

The Arizona Senate passed House Bill 2928 on May 7, 2025, setting statewide minimums and review standards for accessory dwelling units (ADUs) while preserving local flood and historic-district exceptions. Sponsors described the changes as building on prior bipartisan work to expand housing options.

Senator Bullock introduced a floor amendment that required that county ADU rules allow units to be at least 75% of the gross floor area of the primary dwelling or 1,000 square feet, whichever is less, and clarified that ADU rules must not override drainage and flood-control regulations or apply to lots in high-noise or accident-potential zones. Senator Dunn offered an amendment to exempt properties designated as historic by national or local registers from the administrative review requirements; the Senate adopted both amendments. The committee of the whole then reported the bill as amended and the Senate passed HB 2928 on third reading by a recorded vote of 21 ayes, 6 nays and 3 not voting.

Why it matters: the bill standardizes ADU allowances across counties to expand housing options and affordability while leaving room for safety and historic-preservation exceptions. Sponsors framed it as bipartisan progress toward more housing supply.

Action summary: amendments adopted on the floor; committee of the whole reported HB 2928 as amended; Senate approved the bill on third reading and instructed the secretary to transmit it to the House.

(Ending) Supporters urged further bipartisan work on housing; opponents voiced concerns at the microphone during the roll call, but the bill passed with a clear majority.