What Are the Common Causes of Commercial Roof Leaks?

A leak in your commercial property’s roof is not only frustrating and irritating but also dangerous for you and your employees. That’s why you need to be ready to make repairs to prevent further damage to both your roofing and the rest of your property. But to fix the leak properly, you need to know its cause.

To save time and minimize stress, we’ve prepared a list of common causes of commercial roof leaks. We will also teach you how to identify them so you can decide the best course of action for repair.

What Are the Telltale Signs of a Leaking Commercial Roof?

Before getting into the causes of a leaking commercial roof, here’s how to spot leaks.

  • Stained Walls or Ceiling: No matter the type of ceiling you have, prolonged exposure to moisture will lead to stains. If the leak is near a wall, the area will become discoloured and the stain will run down the wall.
  • Mould and Odour: Is there a foul smell on your property? It could be a red flag for mould. Moisture-rich environments, as a result of water continually entering your facility, are the perfect breeding ground for mould.
  • Visible Damage: Some signs are easily visible such as open seams, holes or blisters in the membrane, damaged flashing, and standing water on the roof due to clogged drains.
  • Dripping Water: If water is dripping above your head, your commercial roof is leaking.
  • Buckling or Curling Shingles: If your facility has a shingle roof, buckling or curling of shingles is a common indication of a leak. Curling is when shingles bend at the corner and lift away from the roof, whereas buckling is when shingles cave in at the centre, thus creating gaps.
  • Bubbles on the Roof: Moisture accumulation under the roofing cover due to a leak can cause bubbles or raised portions of the roof.
  • Higher Energy Bills: If your energy bills have skyrocketed, it could be a sign of a roof leak. This is because leaking water can saturate your insulation before moisture enters your building. As a result, your property can’t remain cool in summer and warm in winter and your energy bills will be higher than what you used to pay.


6 Common Causes of Commercial Roof Leaks


Even with regular maintenance, harsh weather can take a toll on your business’s roof. Before you figure out how to go about fixing it, you need to figure out the source of your leaky roof.

1) Aging Roofing System

Nothing lasts forever, and a commercial roofing system is no exception. Flat roofs have a lifespan of 15 to 20 years if properly maintained. After that, they start deteriorating and need to be replaced. The severity of the deterioration depends on the material used and environmental factors. Before it gets beyond repair, it’s advisable to inspect the damage and replace your roof.

2) Poor Design

An important consideration when designing and installing commercial roofs is deciding where the water will drain. If the contractor fails to address this issue, the final product is a poorly designed roofing system. This can create significant problems, like pooling water. Considering how big your commercial roof is, puddled water can cause unnecessary weight on your building’s structure, risking a leak. It can also cause the roof to sag and deteriorate, and moss to build up.

3) Insufficient Drainage

Ideally, a commercial roof should have a well-designed drainage system with scuppers, gutters, and internal drainage pipes to avoid waterlogging. However, if your roofing system doesn’t have sufficient drainage or the drainage system isn’t working adequately, rainwater will collect on the roof and cause leaks in the building. Make sure you inspect the drainage regularly for damage or blockages, as this is the best way to prevent drain-related problems.

4) Damaged Membrane

A roof’s membrane is the protective layer that prevents water penetration. Over time, general wear and tear, hail, debris and mechanical damage can cause cracking, splitting or shrinking. This allows water to leak through the membrane and saturate the underlying insulation. If you act quickly, you can repair the area with a patch; otherwise, a replacement will be necessary.

5) Damaged Flashing

Flashing protects your roof membrane’s exterior edges. This section of metal is designed to fit in corners or conjoining areas of the roof. It is generally installed in chimneys, skylights, interior walls, and roof edges to make these areas watertight. If your flashing fails or isn’t installed properly, it will start to lift off the roof, thus allowing water to seep in.

6) Improper Sealing

A roof should be properly sealed to prevent premature aging and leaks. If your roofing contractor cut corners or didn’t seal the roof well, it could compromise your building’s structure. The result is the roof’s membrane having gaps and air bubbles where water can collect. Some of the common sources of leaks due to improper sealing include pipes, drains, HVAC units, gas lines, and vents.


Don’t let commercial roof leaks catch you off guard. Be prepared by inspecting your property’s roof for obvious signs and understanding why it might be leaking. We hope we’ve helped you understand the common causes of commercial roof leaks so now you’ll be able to decide how to deal with it. Get in touch with a reliable and affordable commercial roofing company to get your roof repaired and prevent further damage.

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