AB 306 would, from June 1, 2025, to June 1, 2031, prohibit cities and counties from making changes to state building standards affecting residential units unless the California Building Standards Commission deems them necessary as emergency measures to protect health and safety. It also requires the Commission to reject any local modifications to residential building standards during this period unless they meet emergency criteria. By imposing these limits, the bill creates a state-mandated local program and asserts that these changes address statewide concerns, applying to all cities, including charter cities.

The bill further restricts the Commission and other state agencies from considering, approving, or adopting any new building standards affecting residential units unless deemed necessary for health and safety emergencies. It suspends the normal 18-month code adoption cycle for residential standards during this timeframe. AB 306 emphasizes the need for statewide consistency in residential construction standards and declares itself an urgency statute, meaning it would take effect immediately upon passage.