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

2, applies the California Residential Code to detached one- and two-family dwellings and townhouses up to three stories with a separate exit, and their accessory structures. It then carves out an exception: certain occupancies that would normally have to comply with the more demanding California Building Code can instead be built under the simpler Residential Code, but only if the building carries a residential fire sprinkler system complying with Section R313. 5, owner-occupied lodging houses with five or fewer guest rooms, and care facilities serving five or fewer people, whether for custodial care, medical care, or care within a single-family dwelling.

In effect, the sprinkler system is the trade-off that lets a small mixed-use or care occupancy use residential-scale construction rules instead of commercial-grade Building Code requirements. 210(S): an ADU is not required to install fire sprinklers if sprinklers are not already required for the existing primary dwelling, and if adding an ADU would trigger a sprinkler requirement purely because it increases the property's livable floor area, that new requirement cannot be imposed on the primary dwelling either. 210(R) further requires every ADU to comply with all Municipal Code provisions on water, sewer, electrical, drainage, and fire and emergency service adequacy, along with applicable building, fire, health and safety codes generally.