Ponding on a flat roof top

Repairing ponding problems...

   *Customers with flat (low-slope) roofs often have questions about standing water. Over time, water standing on a roof surface will damage roof coatings and roofing materials. Standing or “ponding” water eventually leads to roof leaks, damage to roof and deck materials, and damage inside the structure.

By definition, all properly designed and constructed roofs should have adequate and proper drainage. This means at least 0.25 inch per foot roof slope with proper grading and placement of drains or outlets. Roofing practice forbids and roofing material manufacturers usually will not guarantee, any roof subject to prolonged ponding water.

Ponding water is often defined as water that will not drain or dissipate from the roof surface within 48 hours after precipitation. Ponding water may also result from other water sources such as leaking cooler lines and pans, AC-condensate lines and pans, and similar sources. Water condensation, a cool weather problem, can also occur frequently in winter weather.

Recommended Solutions

Eliminate any water leaks coming from AC units, coolers, or drain lines. Check around drain areas for roof debris or roof patching materials that may be blocking drain exits and remove them. On granulated roofs, remove all loose mineral granules as they trap moisture.

Refer all other ponding problems that you wish permanently fixed to a qualified roofing contractor. The contractor may suggest repitching the roof, installing crickets to redirect water, additional drains, the opening of existing drains, or other procedures. Professional solutions are always best.