People call them flat roofs, but a well-designed low-slope roof still needs to move water. Water that sits too long finds weak details, ages materials faster, and turns small workmanship issues into leak calls.
What creates drainage
Drainage can come from the structure, tapered insulation, crickets, saddles, internal drains, scuppers, gutters, or a combination of details. The goal is not just to get water off the field of the roof, but to move it away from walls, curbs, penetrations, and low spots.
Where problems start
- Clogged drains: Leaves, debris, and lack of maintenance can defeat a good design.
- Low spots: Depressions hold water and can expose weak seams or old repairs.
- Poor crickets: Water collects behind curbs, units, and walls when slope is ignored.
- No overflow path: Secondary drainage matters when the primary drain cannot keep up.
Why owners should care
Drainage is one of the easiest things to overlook in a proposal because it is not as visible as the membrane name. But it can decide whether a roof gives you years of service or becomes a repeat problem.