About Ponding Water on Flat Roofs
Ponding water is defined as water that remains on a flat commercial roof for more than 48 hours after precipitation has ceased. It is a significant issue caused by inadequate slope, blocked drainage systems, or sagging roof decks. Ponding water accelerates the deterioration of roofing membranes, voids many manufacturer warranties, and adds substantial dead weight to the building structure, increasing the risk of leaks and even structural collapse.
Frequently Asked Questions
How is ponding water fixed on a commercial roof?
Solutions include installing tapered insulation to create positive slope, adding new roof drains or scuppers, or clearing existing blocked drainage systems.
Does ponding water void a commercial roof warranty?
Yes, most commercial roofing manufacturers explicitly exclude damage caused by ponding water from their standard warranties.
Why is ponding water dangerous?
Besides causing leaks and degrading the roof membrane, the accumulated weight of water (about 5.2 lbs per inch depth per square foot) can cause structural failure.
