Fullerton, CA Building Safety: Fire Sprinkler Requirements (2026)

2 for existing Group R occupancies citywide: an automatic residential fire sprinkler system must be installed when alterations to an existing building remove more than 50 percent of the existing floor area or roof area assemblies within any rolling two-year period. The code carves out a narrow exception: a sprinkler system is not required for additions or alterations to a building that never had one, so long as no two-year window of work removes more than 50 percent of the total existing floor area. 1: there, the same trigger drops to 33 percent, meaning a smaller remodel can force a full retrofit if the property sits in a mapped WUI fire area, with a mirrored exception for buildings that never had sprinklers and stay under that 33-percent threshold.

1 gives homeowners installing a sprinkler system a choice on alarm wiring: they may install a local exterior waterflow alarm or interconnect the interior smoke detectors to the waterflow switch, rather than being locked into one alarm design. 2 to require that any fire department connection be located within 50 feet of a public fire hydrant, a siting rule the Building Division checks alongside the sprinkler retrofit trigger during plan review for qualifying remodels.