Water stains on a flat roof indicate previous what?

Water stains on a flat roof are most indicative of ponding. When water accumulates on the surface of a flat roof and does not drain properly, it can lead to prolonged exposure of roofing materials to moisture. This standing water can cause stains on the interior of the roof, as well as damage to the roofing material over time.

Ponding often results from inadequate drainage, roofing design flaws, or structural issues, where areas of the roof dip slightly, allowing water to collect rather than flow off. This condition not only contributes to unsightly stains but can accelerate the deterioration of roofing materials, leading to potential leaks or structural problems in the future.

Understanding this condition is crucial for property maintenance and inspections, as it highlights areas that need attention to prevent more serious issues down the line.