ROOF PONDING

ROOF PONDING: The excessive accumulation of water at low-lying areas on a roof that remains after the 48 hours after the end rainfall under conditions conducive to drying. Ponding refers to the retention of water on a flat or low-slope roof. Roof ponding is a key issue for the building designer, facility owner and roof consultant with regard to the long-term performance of the roof system and structure. Ponding is the source of many performance problems such as fungi and vegetation growth, sediment deposition, and leaks. The size of roof ponds increases over time because the weight of the water. Eventually, the structure may not be able to carry the increased load. If not properly addressed, ponding can lead to collapse of the roof structure.