common problem areas of commercial flat roofs

Flat roofs are an excellent solution for commercial buildings. They’re cost-effective, energy-efficient, and easily accessible to employees. Flat roofs also ensure that the building has enough space to accommodate other machines, such as the HVAC system or eco-friendly solar panels. 

While flat roofs will probably not win any aesthetic awards, they’re the functional choice for most commercial and industrial buildings—with good reason, too. Since flat roofs are so different from traditional sloped roofs, however, they come with their own set of unique problems. If you are the owner of a flat-roofed property, you need to know what these common problems are and how to address them quickly.

Pooling water

The main problem with a flat roof is that it’s difficult to drain excess water from the surface. A sloped roof uses gravity, and any pooling rainwater will flow down into the gutters. A flat roof does not have this benefit, and water tends to accumulate there with nowhere to go. 

Most flat roofs solve this problem by having a barely noticeable slope that will allow for water to drain, but there’s little margin for error. If there’s any damage on the roof, excess water tends to pool instead of draining. This accumulating can cause long-term damage to both the protective roofing material and the structural integrity of the roof itself. 

The longer the problem is left unresolved, the more likely it is that the roof will start to leak and cause additional damage to the building. You can also expect pooling water to promote the growth of mold, algae, and moss, all of which can significantly damage the roof. 


Buildings tend to shift and settle over time, and this includes the roof area. There is usually a bit of leeway between the roofing membrane and the building itself, but as the structure expands and moves, this space may change. 

The roofing membrane is a large, relatively inflexible sheet of material, so this shifting can cause a permanent buckling. The roof weakens at the areas that have buckled, which can result in the entire roof membrane needing to be replaced much sooner than expected. As with many roofing problems, this issue is only exacerbated by a poor installation job. 


A flat roof is usually open to the elements, and the absence of a slope means that it’s common for large amounts of debris to collect in the corners. Debris blocks drainage, but organic materials also absorb a large amount of water. It can be disastrous during winter, where this accumulating water is constantly frozen, thawed, and then refrozen. 


Harsh sun exposure can damage even the most resilient roofing membrane. The result of constant sun exposure is a flat roof that has started to crack and bubble, which looks like the skin of an alligator. 

While you can ignore small bubbles, a severely alligatored roof represents a significant problem. It can lead to leaks, additional cracks, and even a complete failure of the roofing system.

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