I found the answer for the Florida building code, that is based on the ICC codes
SECTION 1004 SMOKE ALARMS IN OCCUPANCY GROUPS R-3 AND R-4
1004.1 Smoke alarms in existing portions of a building. Whenever an addition is made to a building or structure of a Group R-3 or R-4 occupancy, the existing building shall be provided with smoke alarms as required by the Florida Building Code, Building or the Florida Building Code, Residential as applicable. The smoke alarms in the existing building are not required to be interconnected with smoke alarms in other portions of the base building
