Sprinkler retrofits and ADU rules in San Bernardino County
State law settles the ADU question the same way in every California county. Under Government Code section 66314, an ADU shall not be required to have fire sprinklers if they are not required for the primary residence, and building an ADU shall not trigger sprinklers in the existing house. An older unsprinklered house with a new backyard unit usually needs nothing. A post 2011 sprinklered house usually means the ADU gets them too.
Remodels and additions are local. Each city and the county decide what size of addition or scope of remodel brings the sprinkler requirement in, and the answers differ. Ask the building department for your lot, in writing, before you spend money on drawings.
When a retrofit happens, access decides the cost. Open ceilings during a remodel are the cheap moment. A finished house with a low attic is the expensive one. On mountain lots add freeze design to whatever you retrofit.
Ranges and their sources are on the ADU page, and the area overview is on the San Bernardino County page.
Questions we hear on this work
Does a garage conversion ADU need sprinklers?
Same rule: only if sprinklers are required for the primary residence. If the main house is sprinklered, expect the converted space to be brought onto the system. If it is not, the state exemption generally applies. The city or county confirms at plan check.
Is there a remodel threshold that triggers sprinklers?
It is set locally and we will not print one we cannot cite. Call the building department for the city or the county and ask what triggers sprinklers on an addition or remodel.
What does a retrofit cost?
Installer quotes we have seen in Maryland run roughly $2 to $7 per square foot depending on access. California and mountain work tend higher. A licensed installer walks the house before quoting.
Request a quote from a licensed installer
Send the address below or call. A licensed C-16 fire protection contractor who covers San Bernardino quotes the job on their own paper.
Call (951) 717-3628