Flat roofs, while not entirely flat, have a slight pitch to allow water drainage. For flat roofs, gutters must be carefully designed to manage water flow efficiently. Box gutters are a popular choice for flat roofs due to their high capacity and ability to handle large amounts of water. These gutters are integrated into the roof structure, making them less visible and providing a sleek appearance.
Source
This post first appeared on https://gutterpros.com/