Sprinkler retrofits and ADU rules in Corona, Norco and Eastvale

Norco’s acre lots and Corona’s older neighborhoods make this ADU territory, and state law sets the sprinkler rule. Government Code section 66314: an ADU shall not be required to provide fire sprinklers if they are not required for the primary residence, and building an ADU shall not trigger sprinklers in the existing primary dwelling. An older house without sprinklers usually adds a detached unit without them. A sprinklered Eastvale house usually means the ADU gets them.

Remodel and addition triggers belong to each city and to the county, and they differ. We will not print a threshold we cannot cite. Ask the building department for your lot, in writing, before you draw.

When a retrofit happens, access is the cost. Open ceilings during a remodel bring it close to new construction pricing. A finished house costs more per square foot. On a Norco well lot, a retrofit may also mean adding a tank and pump.

Ranges and their sources are on the ADU page, and the area overview is on the Corona, Norco and Eastvale page.