A flat roof is generally considered the best way to go for a commercial property. Not only does it allow a convenient place to house HVAC equipment and other large building necessities, but it also makes servicing such equipment a relative breeze. Yet like all roofs, a flat roof is subject to certain problems--leaks being chief among them. If you would like to learn more about what tends to cause such leaks, read on. This article will discuss three of the most common sources.


Ponding refers to the phenomenon of water that remains on a flat roof in excess of 48 hours. Water that is allowed to hang around that long is almost sure to cause problems down the line. Sooner or later, it will find a way to penetrate beneath the covering on your roof. Not only that, but it will greatly hasten the rate of moisture-related damage to the roof itself.

In the simplest case, ponding will occur as the result of roof drains, gutters, or scuppers that have become blocked with debris, thus preventing water from adequately draining from the roof. Ponding may also occur should the insulation sitting beneath the roofing membrane become excessively compressed by heavy weight. Areas of ponding will only tend to grow worse with time, since the weight of the water will gradually cause the decking beneath the roof to deflect downward, leading to a water-gathering declivity.

Perimeter Flashing

Unless it has become ripped or torn, a roofing membrane represents a highly waterproof barrier. Yet even an unblemished roofing membrane has its Achilles' heel: the place where the edge of the membrane meets the edge of the roof. This vulnerable line is generally protected with flashing designed to keep water from getting beneath the membrane.

The problem is that such flashing is generally much less reliable than the membrane itself. Even small installation errors may allow leaks to penetrate. Likewise, flashing has a tendency to come loose during periods of high winds. It is also subject to develop cracks or tears when exposed to sunlight and temperature changes over many seasons.

Penetrating Elements

A commercial roof will always contain a handful of structural elements that penetrate the surface of the roof. These may include such things as skylights, plumbing vents, and pipes. The places where these features come together with the roof have to be carefully protected using pitch pans, rain collars, pipe boots, and other protective features. These features must be carefully monitored to ensure that they have not become compromised in such a way that will allow water to penetrate beneath the outer surface of the roof.

For more tips, contact a company like BCI Metal Roofing.