Why Flat Roofs Can Develop Ponding Over Time

One of the more common problems that can develop with flat roofs over time is ponding of water. This standing water can lead to roof deterioration and eventually leaks. Even with careful construction and low areas can develop for a number of reasons, including:


On new buildings it is natural for the structure to settle into its foundation. In most cases this settling does not cause significant damage, however on larger commercial buildings with flat roofs, low spots can develop over time causing ponding.

Changes in the Ground Environment

The ground around and near a structure can undergoing changes in the form of the freeze/thaw cycle, heavy rain and other environmental changes. These changes can shift a building’s foundation and in extreme cases cause the roof to sink.

Compromised Roof Insulation

If roof insulation is not properly sealed from the elements or becomes compressed, its structure can become compromised. If water leak underneath the roofing material it can saturate the insulation, causing it to sag and create a low spot in the roof. Roof insulation damage is most likely to occur when repairs are being made or when heavy equipment is used on the roof during HVAC replacement or other work.

Poor Drainage

If water is not able to drain adequately drain from a flat roof and enough volume builds up it can cause depressions in the roof, which can continue to get worse with each storm as the cycle continues, create a steeper slope.

Have questions about your flat roof? Call The Roofing Company. We can help with all your commercial roof maintenance and repair needs.