Flat roofs are common on commercial buildings, but they come with a unique set of challenges. One of the most frequent—and potentially damaging—issues is ponding water. Ponding water occurs when rain or melted snow collects on your roof and doesn’t drain away as it should. Left untreated, it can shorten your roof’s lifespan, compromise your building, and drive up maintenance costs.
In this article, we’ll cover what ponding water is and why it’s a problem, the most common causes, the warning signs you should look for, how to fix it, and what you can do to prevent it from happening in the first place.
What Is Ponding Water and Why Is It a Problem?
Ponding water is defined as water that remains on your roof for 48 hours or more after rainfall or snowmelt. While a small amount of standing water might seem harmless, the long-term effects can be significant:
- Structural stress: The added weight of standing water puts unnecessary pressure on your roof deck.
- Membrane damage: Roofing materials can weaken and deteriorate more quickly under constant water exposure.
- Leaks and interior damage: Ponding water often finds its way inside, leading to water stains, mold, and costly repairs.
- Algae and mold growth: Moisture encourages biological growth, which further damages the roof and affects building aesthetics.
- Higher maintenance costs: The longer ponding water goes unchecked, the more expensive it becomes to repair.
Warning Signs to Look For
- Spotting ponding water early is key to protecting your building. Here are the most common red flags:
- Visible standing water after it rains or snows.
- Staining or discoloration on the roofing membrane.
- Vegetation, algae, or mold growth in low spots.
- Premature wear around drains, seams, or rooftop equipment.
- Water marks or leaks inside the building.
If you notice one or more of these signs, it’s time to take action before the damage spreads.
How to Fix a Ponding Water Issue
Short-Term Solutions:
- Unclog drains and gutters to restore water flow.
- Apply temporary patching to low areas or leaks.
These are quick fixes that may provide temporary relief, but they don’t address the underlying issue. Left unresolved, ponding water will return and continue to cause damage.
Long-Term Solutions:
- Improve drainage systems by adding or upgrading roof drains and scuppers.
- Re-slope the roof or install tapered insulation to direct water toward drains.
- Reinforce the roof deck in areas where sagging has occurred.
- Full roof replacement when the system has failed or is near the end of its service life.
Every roof is different, and the right solution depends on the roof’s type, age, and condition. Partnering with a professional ensures you choose the fix that will protect your building for the long run.
Preventing Ponding Water in the Future
Prevention is always more cost-effective than repairs, and staying ahead of ponding water issues requires consistent care. Scheduling regular inspections and maintenance with a qualified professional helps identify potential problems before they become costly repairs. Cleaning drains and gutters on a routine basis—often part of a preventative maintenance plan—ensures water can flow freely and reduces the risk of buildup. It’s also smart to inspect your roof after storms, when hidden damage or drainage issues are most likely to occur. Partnering with a roofing expert makes this process safer and more effective. At Next Phase, we use drones, thermal imaging, and other advanced technology to perform thorough inspections, ensuring no issues are overlooked while keeping your team safely on the ground.
Key Takeaways
Ponding water on flat roofs is more than a nuisance—it’s a serious threat to the health and longevity of your building. By knowing what causes it, recognizing early warning signs, and acting quickly with the right solutions, you can prevent costly damage and extend the life of your roof.
Don’t wait for small issues to turn into major disasters. If you’ve already noticed ponding water—or if you simply want the peace of mind that comes with a professional inspection—contact Next Phase today to schedule a free inspection.
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