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Question: When I went up onto my roof after a rainstorm, I noticed several areas where there is water ponding. Is this a concern?

Answer: The short answer is yes, it can be a concern. The longer answer relates to the question, “what can be done about it?” In an ideal world, there would be no water ponding on roofs. Unfortunately, we don’t live in such a world. Most flat roofs have water ponding conditions, to at least some extent. If the building is fairly new, it probably doesn’t have much of a problem. However, older buildings tend to settle. Plywood, rafters and other supports tend to sag over time. This can cause pockets of water ponding. Also, when buildings were built back in the 1960’s (or earlier), people weren’t paying as much attention to water ponding issues. Many old buildings were built with roofs that have poor slope. As a result, some old buildings have a lot of ponding water. Correcting the problem at this stage could be extremely expensive or (in some cases) impractical. When re-roofing is performed, the issue at hand is, “Is it worth spending a lot of money to correct the problem?” In many cases, the answer is no.

Water ponding that evaporates within 72 hours is generally not considered to be a major problem. Some manufacturer’s use 48 hours as the guideline. In most cases, water ponding doesn’t cause the roof leak (unless it’s very severe). What water ponding can do is to cause the surface of the roof to prematurely deteriorate. This is generally the case in cap sheet surfaced and coating surfaced roofs. It’s usually not a major issue with single ply roofs, but can be with asphalt roofs.

The costs to correct water ponding issues can vary dramatically. Sometimes new drains can be added in strategic locations. However, if water ponding occurs in numerous locations, this can become very expensive and is not a practical approach. In some cases, water ponding problems can be corrected by installing new tapered roof insulation. This could be a consideration when re-roofing is performed. However, it can be very expensive and can double the cost of re-roofing.

If you have ponding water conditions, the best thing to do is to have RAMCON inspect the roof. Our experts can give you an honest, accurate opinion as to what would be the best solution. If correcting water ponding issues makes sense, we’ll let you know. If it’s not cost effective to do, we’ll let you know that too! We look out for your best interests and can help you to make the right decision.