For this particular roof, there are multiple issues visible. The most obviously one is the water not draining properly, otherwise known as "ponding water", which can be seen in the pictures. There are multiple affects that cause this issue; improper installation, bad or inadequate number of drains, sagging or disrupting of slope, and clogged drains. Second major issue is the lack of maintenance. This roof had cracked and ripped seals just about everywhere you looked, which contributed to the roof leak substantially. As noted, this roof has several open areas where the roof system ripped or the rubber seal decayed. Another issue notified, was the shingles on the flat roof system. Anything other than the flat roof system will contribute to the decaying or rupturing of the flat roof. Lastly, This roof has a one way drainage system that uses a gutter at the lower end of the sloped roof. The gutters are filled with water and are not draining properly. A simple fix would be to maintain and clean the gutters regularly.