As earlydean said, the 2000 IRC requires fireblocking at certain areas. It also list products used for firestopping. Firecaulk is not one of them as it is an overkill. In residential we are usually dealing with wood studs, wood joists, wood subfloor, wood sheathing...see a pattern here? The basic idea is to stop the air from going thru the holes for as long as it would take to burn thru the wood. Rockwool is the draftstop of choice in this area.
