All building roofs are subject to destructive effects of sun, rain, and seasonal weather changes, ventilation system, exhaust air, ventilation under the roof, roof loading, traffic on the roof, acid-laden smoke, and the abrasive action of dust and grit borne by high velocity winds. Alternate wetting and drying, freezing and thawing caused by water lying on the roof causes expansion, contration, and rotting, with damage often extending even to the substructure. Drains are plumbing fixture designed to remove any standing water near it. They have gratings made of plastic or metal and are installed at the lowest point in a floor built to slope toward it. The floor drain usually ranges from 2 to 12 inches(5.1 to 30.5com) and 4 inches (10 cm) in diameter. Salient Features Robust designs & Aesthetic apperance Low maintenance Lightweight Easy installation High Performance Corrosion, fire, and heat resistance Hygiene and Sanitation Weather Resistant .