Ponding water is a very common issue that can affect all kinds of roof types and configurations. A high quality roof is very likely to ensure an exquisite durability overtime, but only if you move all the water off. This is your responsibility. On the other hand, a smart installer should know that slope is very important in a dead level roof too. In conclusion, educate yourself and consider a few proactive measures before installing the roof. Feel free to seek help from http://actionroofing.com.au/. The professionals on site are excellent with both fresh roof installations and sophisticated reparations or problems.