Ponding Water On A Flat Roof: How Serious Is It Really?

Ponding water is defined as water that remains on a roof more than 48 hours after rainfall stops. It is one of the clearest early warning signs that a commercial roof is heading for failure.

The damage it causes

Standing water accelerates UV degradation, breaks down adhesives and seams, adds significant dead load, and invites algae and vegetation growth that punctures the membrane.

Common causes

Undersized or clogged drains, deflected decking, compressed insulation, and poor original slope design are the usual culprits.

What to do about it

Start with drainage: clear drains and scuppers, add overflow drains where required, and use tapered insulation crickets to redirect water. A roof coating system applied over corrected drainage will keep the repair watertight for decades.