Firestop Radiation Shield for 8" Inner Diameter Chimney PipeThe firestop radiation shield is used when passing through a second story floor, and at every floor above, to protect the floor joists where the chimney passes through the floor. The firestop radiation shield is installed on the underside of the ceiling floor framing, with the cylindrical "tube" pointing upward. Example: in a 3 story home where the appliance is on the ground floor the support box is installed in the 1st floor ceiling, a radiation