If with a firewall on two (2) sides

If with a firewall on two (2) sides or on one (1) side and the rear property line, the footprint of a proposed building/structure shall be measured horizontally from the opposing property lines in case of a firewall on two (2) sides or from the rear property line with a firewall to the outermost faces of the opposite exterior walls of the building/structure; provided, that the applicable stipulations of the Fire Code are strictly followed;