6 ways that roofing materials can play a role in addressing ponding water

In the commercial roofing industry, roof penetrations are a necessary evil – skylights, vent stacks, HVAC units, etc.

Not only are penetration areas the most vulnerable to roof leaks, they can also make it difficult to maintain positive drainage after a rain or snow event.

If water flow is obstructed by penetrations, ponding water will occur. Left untreated, it can lead to premature breakdown of your roof membrane, mold growth, insect infestation and more.

In these vulnerable ponding water areas that can’t be addressed by simply diverting water flow, facility managers can work with their roofing providers to attack the issue with reinforced materials.

  1. Thickness
  2. Reinforcement
  3. Specific gravity
  4. Color
  5. Seamless / Penetrations
  6. Timing
ponding water on commercial rooftop

Simon Roofing studies this issue extensively in our research and development lab, and we’ve developed products specifically to address ponding water conditions. Each tailored solution takes the following factors into account:



A membrane’s thickness plays a role because the polymer is going to deteriorate over time when exposed to the elements, and it’ll deteriorate even quicker with ponding water. A thicker membrane in select ponding water areas can lengthen the overall roof’s expected life.


Adding a layer of polyester reinforcement to the membrane, where possible, can strengthen the membrane in the presence of ponding water. It also lessens the ability for water to penetrate the membrane.

Specific gravity

The heavier the material is compared to water, the better it will be able to shed water away. For ponding water areas, a product should have a high specific gravity, low porosity, superior adhesion and high-tensile reinforcement. Products like these may be cost-prohibitive for the entire roof, but they can make fiscal sense in ponding water areas.


The color of the material can make a difference. White roofs aren’t great for ponding areas because they don’t hold the heat. Retaining heat with a darker colored roof, like gray, will help the ponding water evaporate quicker. Even in warmer climates, it can make sense to spot color the ponding areas gray.


When ponding water sits above seams or around penetrations, the resulting deterioration makes it more likely for water penetration through these weakest points in a roofing system. Look for materials that are seamless or be mindful to reinforce areas where sheets of material overlap around penetrations.


When you can field-fabricate the roof in a restoration or re-roofing situation, that’s an ideal time to address ponding areas. Take a look when the roof is done and look at the ponding areas where you won’t be able to move water, and address them right then and there.


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