What situation suggests that there may have been water pooling on a flat roof?

Water stains are a clear indicator of water pooling on a flat roof. When water accumulates, it can seep through the roofing materials and lead to discoloration and staining on ceilings or walls directly underneath the affected area. These stains usually appear as dark patches that can either be small or larger depending on the extent of the water accumulation.

In a flat roofing structure, proper drainage is critical, and the absence of it can lead to water being trapped on the surface. This stagnant water contributes to moisture problems, and over time, can damage the roofing material itself. Noticing water stains is thus a significant clue for home inspectors to investigate further for potential structural and material issues related to roof drainage.