4 Reasons Your Commercial Roof Keeps Leaking...And How to Fix It

Have you paid thousands of dollars for multiple roof repairs only to find that your roof just keeps leaking? Unfortunately, this situation is quite common. At Gideon, we work with many building owners who have hired two, three, or even four different contractors - all of whom promised a fix but couldn’t deliver. 

Fortunately, we’ve been repairing and replacing commercial roofs for over 20 years, and we know what it takes to diagnose your roof and fix it right the first time. In this article, we’ll discuss the 4 most common reasons your roof keeps leaking despite all those repairs - and what you can do about it.

The 4 Reasons Your Commercial Roof Keeps Leaking

1. You Didn’t Find the Actual Leak Source in the Roof

The Problem

The most common reason your roof keeps leaking after a repair is quite simple: you or your contractor did not find the leak. Finding a leak is not always straightforward. Just because the water is coming through the ceiling in one area does not mean that the water entered your roof in that area. Water can travel a considerable distance once it enters a roof, as the insulation soaks it up like a sponge and spreads it throughout the assembly. It’s not until the water finds a vulnerability in the decking that it starts seeping into your building - and this may happen far from where the water penetrated the outer membrane.

The Solution

The solution is to find all the locations inside your roof assembly holding water. This can be done with a thermal imaging camera (waterlogged areas are warmer than dry ones), a moisture-scanning tool called a Tramex, or by cutting open the roof and examining the insulation. Once your contractor has discovered all areas of water penetration, he can scan the roof for the most likely sources of leaks, such as nearby seams or cracks in the membrane.

2. You Used the Wrong Material to Patch the Roof

The Problem

It’s not uncommon for building owners or even contractors to attempt to patch their roofs with asphalt purchased at the local supply store. Unfortunately, there are two problems with this. First, asphalt is incompatible with common roof membranes like TPO or PVC; it will damage them. Second, the plasticizers that make asphalt flexible tend to leach out in the sun, making the asphalt brittle over time. The natural movement of the building then causes the asphalt to crack, once again exposing the leak point in the underlying roof. 

A related problem is when someone simply buys a sealant product and applies it to the leak area. While these products can be used on most roofs, different kinds are appropriate for different applications, and they are not UV stable, so they will eventually burn up in the sun.

The Solution

The solution is to use repair materials that are a) compatible with your existing roof, b) compatible with the application, and c) UV stable. Different roofing materials have different chemistries, and materials used together have to be able to chemically bond. Different sealants have different properties and can only be used for specific applications (some, for instance, are best for horizontal surfaces, while others are best for vertical). Sealants should also be covered with another material (like an elastomeric coating) that is UV-resistant.

3. Your Contractor Didn’t Remove Saturated Insulation During Your Roof Repair

The Problem

If a leak has already saturated a section of the underlying insulation, all waterlogged insulation must be removed and replaced before you patch the roof. You risk future leaks if you neglect to remove even a small part of the saturated insulation. Why? Saturated insulation compresses as the water damages its structural integrity, creating a depression in the roof where water can pool during a rain storm. The pooling water then creates pressure on the roof membrane and can wear out seams and flashings, leading again to a leak.

The Solution

Your contractor needs to find and replace all saturated insulation. As mentioned above, this can be done with an infrared scan, a Tramex tool, or a physical inspection of the interior assembly.

4. Coating Without Fixing the Underlying Structural Problem

The Problem

Another mistake that can be made is coating a roof without fixing the underlying structural problem. This could be a matter of neglecting to remove saturated insulation, or it could be a matter of simply coating over a failed seam. The problem with the latter is that if the seam itself has not been repaired, it will continue to experience movement as a result of the building shifting as well as expansion and contraction from temperature fluctuations within the roof assembly. When this occurs repeatedly, it will gradually break the coatings apart, exposing the faulty seam to the elements again.

The Solution

A successful patching job is not a matter of simply laying down the sealant. It must be applied to the roof in a certain way based on its viscosity, and the seam must be re-adhered to the roof surface. 

The best way to apply sealant is in a “fabric-reinforced 3-ply”. In this type of patch, the sealant is used as an adhesive to reconnect the broken seam to the roof. Then a polyester fabric is laid down to give structural reinforcement to the sealant. Finally, more sealant and a UV-stable coating are applied on top of the fabric to waterproof it and protect it from the sun.

The Upshot

At the end of the day, no one wants to pay for something that doesn’t work. This is especially true when it comes to commercial roofing, which only gets more expensive the longer a problem goes unsolved. Now that you’ve learned why your commercial roof repairs may not work, call us. In a free, 15-30 minute discussion, one of our nationally recognized experts can assess your situation and give custom recommendations for your roof.