INVERTED ROOF CONCRETE DECK Z100-C-R-XJ-85 Drain installed in an insulated concrete deck. Drain is illustrated with underdeck clamp (-C), roof sump receiver (-R), vertical expansion joint (-XJ), and Zurn ballast guard extension (-85). The (-XJ) option is also available in 8" and 12" diameter drains. (See Z121 and Z125.) ROOF DRAINS