What Causes Commercial Roof Leaks (And How Coatings Prevent Them)

NFW Author
4 days ago
2 min read

Commercial roof leaks rarely happen suddenly. In most cases, they are the result of predictable failure points that develop over time. Understanding where and why these leaks occur is key to preventing them altogether and avoiding major repairs later on.

The Most Common Source: Seams and Joints

Traditional commercial roofing systems rely heavily on seams. Whether it is TPO, EPDM or built-up roofing, these systems are installed in sections that are joined together.

Over time, seams can:

Separate due to thermal movement
Degrade from UV exposure
Fail under standing water conditions

Once a seam fails, water can enter the system and travel beneath the surface, often spreading far beyond the original entry point. Roof coatings eliminate this issue entirely by creating a seamless membrane across the entire roof. With no seams, one of the most common leak sources is removed.

Rooftop Penetrations and Mechanical Openings

Every commercial roof has penetrations such as vents, HVAC units, drains and piping. These areas are particularly vulnerable because they require flashing and sealing to prevent water intrusion. As materials age, these seals can crack, shrink or pull away from the surface. Even small gaps can allow water to enter.

Fluid-applied coatings conform around these penetrations, sealing irregular shapes and creating a continuous barrier. This reduces the risk of localized failure around critical points.

Ponding Water, Drainage Issues & UV Degradation Over Time

Flat and low-slope roofs are especially prone to ponding water. When water sits on the surface for extended periods, it accelerates material breakdown and increases the likelihood of leaks. Standing water adds constant pressure to weak areas, especially seams and flashing points.

Sun exposure is one of the most overlooked causes of roof failure. UV radiation gradually breaks down roofing materials, making them brittle and prone to cracking. Once the surface begins to degrade, it becomes easier for water to penetrate the system.

Certain coating systems, particularly silicone-based coatings, are designed to withstand ponding water without breaking down. In addition, reflective roof coatings act as a protective barrier against UV rays. By reducing direct exposure, they slow down the aging process and help maintain the integrity of the roof.

In Alberta, roofs experience extreme temperature swings. Expansion during the day and contraction at night create constant movement within the roofing system.

Over time, this movement causes:

Cracks in materials
Separation at seams
Stress at connection points

Elastomeric coatings are designed to move with the roof. Their flexibility allows them to expand and contract without cracking, reducing stress on the system.

A Preventive Approach to Roofing

At NFW, we focus on identifying risks before they become failures. As experienced insulation contractors in Red Deer, NFW provides commercial roof coating systems that protect your buildings from most common sources of leaks, as well as supportive spray foam insulation services.