HB 2928 Summary

• Municipalities with populations over 75,000 must adopt regulations allowing at least one attached and one detached accessory dwelling unit (ADU) as permitted uses on single-family residential lots, plus one additional detached ADU on lots of one acre or more if at least one is deed-restricted as affordable.

• ADUs must be allowed at a minimum of 75 percent of the primary dwelling's gross floor area or 1,000 square feet, whichever is less, and municipalities cannot require matching exterior design, additional parking, familial relationships between occupants, or rear/side setbacks exceeding 5 feet.

• Counties must adopt similar ADU regulations by January 1, 2026, with identical size and design standards, and may require one ADU on larger parcels to be restricted-affordable (rented to households earning up to 80 percent of area median income).

• Municipalities and counties cannot prohibit or regulate ADUs as separate long-term rentals or vacation rentals more restrictively than single-family dwellings, but owners with ADUs constructed after September 14, 2024, must reside on the property if operating the ADU as a vacation/short-term rental.

• If municipalities fail to adopt ADU regulations by January 1, 2025, or counties by January 1, 2026, ADUs become permitted uses without restrictions on all residential-zoned lots; exemptions apply to tribal lands and areas near military or public airports with noise levels exceeding 65 decibels.