Modesto, CA Fire Regulations: Smoke Detectors (2026)

2710 requires single or multiple-station smoke alarms in Groups R-2, R-3, R-4 and in other dwellings not regulated as Group R occupancies, regardless of occupant load. Alarms are required on the ceiling or wall outside each separate sleeping area in the immediate vicinity of bedrooms, inside each room used for sleeping, and on each story of the dwelling unit including basements and cellars (crawl spaces and uninhabitable attics are excluded). For split-level units without a door between adjacent levels, a single alarm on the upper level covers the lower level if that lower level sits less than one full story below.

2711 governs the power source: alarms in Group R occupancies must draw primary power from building wiring served by a commercial source, backed up by battery, and must emit a low-battery signal; the wiring must be permanent with no disconnect switch other than required overcurrent protection. A battery-only alarm is permitted where no construction is underway, where the building has no commercial power source, or during alterations that do not expose the structure by removing interior wall or ceiling finishes, unless an accessible attic, crawl space or basement would allow wiring without removing those finishes.

2712 requires interconnection: where more than one alarm is required within a dwelling unit in Groups R-2, R-3, R-4 and unregulated dwellings, all alarms must be wired so that one activating sets off every alarm in the unit, audible in every bedroom over background noise with doors closed. Interconnection is not required in buildings undergoing no alterations, repairs or construction, or where existing-area work does not expose the structure.