Ponding Water on Your Commercial Roof

Downpours from summertime storms can be disruptive, and even disastrous, as we’ve seen in 2021 from the weather events that affected southeast Michigan. Flooded basements and closed freeways were at the top of the news, but it’s worth considering what might have happened on the top of your building – specifically to your commercial roof.

If your building has a flat or low-sloped roof, be aware that collected or “ponding” water has the potential to create problems. Although it’s not uncommon for puddles to linger on the rooftop after a rain, if it’s not drained or dissipated within 48 hours or so, there could be consequences that develop over time.

Perhaps most important is the weight of ponding water. One inch of water on one square foot of roof surface weighs about five pounds. So, an inch of water in a relatively small 20-foot by 20-foot area would add 2000 pounds – a ton – of weight. Increase the area or the depth of the water and it’s easy to see how this added weight could potentially compromise your building’s structural reliability.

Standing water can foster the growth of algae and other organisms that can deteriorate the surface of some roof membranes. It can also intensify sunlight, which can contribute to the breakdown of the roof surface.

The pressure of standing water could also force it through tiny penetrations and into the building, plus create stress on seams and other areas that may be aging and beginning to lose their watertight integrity.

Inadequate drainage is usually the culprit when it comes to ponding water, and that could be due to one or more factors, including: clogged gutters and downspouts, a poor roof design (e.g., insufficient number of channels for water to get off the rooftop), a substandard initial installation, roof insulation that’s been compressed from foot traffic, or sagging in the building structure due to age.

Problems may be solved by a simple fix, such as ensuring that drains, gutters and downspouts are clear and flowing freely. More extensive approaches may include adjusting the roof slope by installing crickets (triangular structures that elevate areas of the roof surface) or tapered insulation panels. Both of these additions would be integrated into the existing roof to create a slope and positive drainage.

If you have a rooftop ponding water issue, the pros at Versatile Commercial Flat Roofing have the experience, materials and tools to resolve rooftop drainage issues so that your staff, visitors and assets are protected. We’ll evaluate the situation and propose a solution to eliminate the issue, either by repairing it, if practical, or replacing it with a new roofing system. If a roof replacement is the best course of action, it’s important to note that roof system manufacturers commonly exclude ponding water in their warranties. However, some manufacturers have no warranty exclusions for ponding water.

We look forward to working with you on your next roofing project. Contact us today.