Greg,
Here in VA there is a statewide code that all levels have a smoke detector and that there be a smoke detector in every sleeping room and one outside the sleeping rooms and that they all be powered from the house power and all have battery backup and they all be inter-connected. Except, the state code also says we don't have to interconnect them on remodeling projects where the drywall is not removed and there is no path to inter-connect them. In that case, we are supposed to install them, but not interconnect the ones that can't be wired.
