The biggest enemy of any flat roof is standing water. As you can probably guess, when water has nowhere to go, it just sits there and slowly eats away at the membrane. To prevent that, we installed ISO board across the deck and tapered it to create a slight pitch, giving rainwater a clear path to drain off the edges. Once the slope was set, we layered modified bitumen with the granulated finish you can see in the photos. The result is a clean, watertight surface built to handle the heavy Central Florida rains without ponding becoming an issue down the road.