Roofs play a key role in protecting building occupants and interiors from outside
weather conditions, primarily moisture. The roof, insulation and ventilation must all work
together to keep the building free of moisture. Roofs also provide
protection from the sun. In fact, if designed correctly, roof
overhangs can protect the building's exterior walls from moisture
and sun. The concerns regarding moisture, standing water,
durability and appearance are different, reflected in the choices of
roofing materials.