Typical scope
- Drain, scupper and gutter clearing and rebuilds
- Tapered polyisocyanurate insulation, crickets and saddles cut to slope
- Additional roof drains and through-wall scuppers where outlets are insufficient
- Sump pans at existing drains where the deck dips the wrong way
- Overflow provision so a blocked primary drain does not load the deck
- Moisture survey to establish whether the insulation under the pond is already wet
Why ponding destroys a roof
Standing water attacks several ways at once. It magnifies UV degradation of the sheet. It keeps seams and flashings permanently wet, so any marginal detail becomes a leak. It grows algae and vegetation whose roots find laps. And it is heavy, roughly 5.2 pounds per square foot for every inch of depth, so a pond deflects the deck slightly, which deepens the low spot, which collects more water. That feedback loop is why ponding rarely stays the same size.
It also has a contractual consequence: most single-ply and coating warranties explicitly exclude damage occurring in areas of ponding water. A perfectly installed roof with a drainage defect can be outside its warranty from day one.
How it is actually corrected
Clearing the outlets is step one and is sometimes the entire answer, leaves, gravel and debris cause a surprising share of ponding. Beyond that, if the deck has deflected or the roof was framed dead-flat, the standard solution is tapered insulation: polyiso boards cut to a slope, typically a quarter-inch per foot, built into crickets and saddles that route water to the outlets. If the drains are simply too few or badly placed, adding a drain or a scupper does more than any amount of tapered board. Sump pans help where the deck dips slightly around an existing drain.
The shortcut to avoid
Filling the low spot with levelling compound or piling extra coating into it adds weight exactly where the deck is already deflecting, and it rarely lasts. If a contractor proposes that as the fix for a persistent pond, ask what happens to the load.