The utility model discloses a lightning -arrest area of slope overhanging type for flat roof deck constructs parapet, with the waterproof weak spot setting of support bearing in the below that the parapet bears down on one, avoid support direct puncture parapet bear down on one directly over and the rainwater directly expose on the sleet face, bend the support once more to become to be lighter than 90 and be close to angle and appear and change the rainwater circuit that flows, will follow rainwater water conservancy diversion to the roofing of trickling on the support on, the waterproof wholeness of the finish coat of guaranteeing like this to bear down on one, avoid support bearing seal glue because of long -term reason ageing and the construction carelessness wet by the rain and burnt by the sun becomes waterproof weak spot, change the rainwater and can't trickle to the support bearing around along support direction flow generatrix way messenger's rainwater, have waterproof, prevention of seepage, destroy the finish coat, guarantee the advantage of building energy -saving insulation performance.