Ponding

Ponding is the accumulation of rain water on flat roofs. A minimum slop of ¼ in./ft. (1.19°) is usually required for flat roofs to drain rainwater. As the roof deflects under the rain load, additional water is retained by the roof which leads to even more deflection of the structure allowing a deeper pond to form. If the structure does not have enough stiffness to limit the progression, failure may occur.

Ponding

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