Leaks on any roof can be hard to identify. But it’s especially tough to find out where leaks on flat roofs are coming from.  The leak rarely originates from directly above the area that water is appearing in your home with a flat roof.  Since the water doesn’t travel down naturally, it takes the least resistant path and can appear anywhere around your house.   Most flat roofs fail in similar ways, which means there are a few key places you should look at first.

Failed Flashing

The caulk sealing your flashing to roof elements has the shortest lifespan of the roofing materials.  When the roof naturally expands and contracts with the seasonal temperatures, that pulls at the flashing and the caulk, which will eventually crack.  Unlike sloped roofs, flat roofs have some pressure exerted on them from all sides, and if that stress builds up, the roof can crack.  Unfortunately, a crack in your roof points to structural damage as well.  If you see a crack in your flat roof, it’s time to call a professional roofing company immediately.

Ponding Water

Standing or “ponding” water is one of the most common issues faced by flat roofs.  It is characterized as any water that remains on the roof for longer than 48 hours following precipitation.  The longer the water remains on your roof, the greater the chances are that it will lead to damaging leaks.  The roof should be designed with a slight slope so that water can easily find its way to the drain points.  Sometimes we find that even flat roofs that were carefully designed in this way can eventually be faced with ponding as they age.

Since flat roofs don’t have a slope for water to travel down and away from the home, they can be especially susceptible to pooling water.  Usually, pooling is caused by blocked drainage that you can easily remedy by clearing debris out of the drains.  Your roofing materials should be able to withstand occasional pooling water.  However, if the water is allowed to stand for extended periods, it will eventually erode the materials and cause a leak.

Be aware that, even if ponding doesn’t lead to leaks, it still represents a significant roofing problem.  The reason for this is, as time goes by the enormous weight of standing water will gradually make the problem worse.  Roof leveling can resolve minor drainage issues, but more serious issues of ponding require changes to the underlying roof structure itself.

It is important that you regularly monitor your roof for any signs of standing water.  Gutters, downspouts, wall scuppers and drains will lead to ponding if not functioning properly.  Ponding is more likely to occur around large rooftop units because the weight of these structures will prevent the structure of the underlying roofing supports from working as designed, leading to ponding.

Blisters or “bridging” in the Roof Membrane

Flat roof membranes are prone to blistering and “bridging”.   Blisters look like bubbles forming under the roof membrane.   Over time, the adhesive lets go and the expansion and contraction of the membrane leads to a bubble or wrinkle formation.  This is a sign that the membrane is nearing the end of its useful life.  Bridging is the shrinking of the membrane that leads to stress on the seams, and flashings.  Bridging can be pronounced in EPDM membranes as they age.  Bridging and blistering can lead to cracks in the membrane.  EPDM membrane will literally tear itself apart over time if left alone.

Damaged Membrane

Unlike asphalt shingles that are separate pieces, most asphalt flat roofs have one single membrane.  As the seasons change and the house shifts, that membrane can buckle, crack, and shift.  If the membrane has been punctured or has a small crack, it may simply need a patch.  However, buckles and damages due to age cannot be fixed, and your roof will need to be replaced entirely.