Alligatoring on commercial roofing membrane.

Since flat and low slope roofing for commercial buildings are built with a wide range of materials, they can fail in several ways.

Repairing a commercial roof can add challenges due to scale and the cost of disruption to the business inside the building. However, many common flat roof problems can be prevented when proactively managed. Let’s take a look at some of the issues we encounter most often and how they can be prevented or repaired.

Table of Contents

Most Common Flat Roofing Problems

  • Roof Leaks
  • Buckling, Blistering and Alligatoring
  • Cracking and Splitting
    • Sudden Impact: Punctures & Tears
  • Flashing Leaks
  • Pooling Water
  • Wind Damage
  • Take the Headache Out of Flat Roof Leaks and More

Roof Leaks

When it comes to common flat roof problems, the final failure mode is a breach of the building envelope. On a steep slope roof, most precipitation slides off before it has a chance to collect inside the building. However, runoff on low slope roofs is limited, and it’s not hard for debris to clog drainage systems like gutters.

Once trapped moisture is inside a commercial property, it can wreak havoc with structural supports, making the building unsafe. Even if it doesn’t degrade materials, moisture trapped in walls and floors encourages mold growth, which can cause respiratory problems for people inside the building (and requires extensive replacement of building components to remediate).

These repairs are costly, and cause major disruption to businesses inside the building.

Regular roof inspections are a must, because spotting common issues early can greatly reduce repair costs, not to mention danger to the people and equipment inside the building.

Buckling and Alligatoring

An asphalt membrane roof is made from the same materials as asphalt shingles; the membrane is a single, uniform sheet. Since the roof is exposed to extreme temperature swings (sometimes daily), it needs to expand and contract to compensate.

Once the roofing material starts to lose its elasticity, it can’t expand and contract evenly, warping the surface. Failed areas must be replaced to restore the roof’s temperature resistance and its ability to create a watertight barrier for the rest of the building.

EPDM (a type of rubber roofing) and liquid-applied roofing also face the same problem as they age. In most cases, the roof membrane can be repaired, replacing failing areas, or applying a new layer over the existing roof. Total failure of an asphalt roof leads to splits and blistering, creating a surface that looks like the skin of an alligator. At this point, you’ll need a roof replacement.

Cracking and Splitting

Other roof issues that need attention are cracking and splitting.

Cracking can be caused by a combination of de-plasticizing roofing material, pressure and impacts. This can be seen on areas of the roofing system that shrink as they dry out. Cracks should be sealed as soon as possible to prevent damage beneath the roof.

Splitting on a commercial roof looks similar to a crack, except the crevice is deeper. This type of problem can be caused by debris strikes or from added weight around vents, HVAC units and solar panels. The chance of developing cracks and splits increases as the roof loses its elasticity.

Metal pitched roofs don’t de-plasticize, but impacts can split the surface. Damaged panels on metal roofs can be replaced, or damaged areas can be covered with a new patch panel.

Sudden Impact: Punctures & Tears

Most impact damage comes from storms. Hail and debris tossed up by the wind can cut into the surface of the roof, so it’s a good idea to get an inspection after any major storm.

While different forms of impact damage are among the most common flat roof problems, it’s more common with older roofs. Over time, plastic and asphalt-based roofing materials lose their elasticity. This lack of flexibility prevents these materials from absorbing impacts, leading to failure.

After storms, foot traffic is also a common cause of impact damage. This can be mitigated by integrating walkways into the roof structure. Of course, there’s always the chance that accidents during rooftop repairs can damage the roof, whether it’s from dropping tools or equipment.

Flashing Leaks

Commercial roof flashing is a thin material, usually metal or plastic, installed where the part of the roof surface meets a chimney, skylight, pipes or HVAC systems. It prevents water from seeping through the roof in those areas.

If flashing is compromised during roof installation or after, gaps allow water to trickle (or rush) through the flat roof materials. Metal flashing can also corrode. It’s important to have routine roof maintenance to identify when flat roof repair is needed to prevent an expensive roof replacement.

Pooling Water

No matter the cause, pools on the surface of the roof accelerate wear, create a breeding ground for moss and algae, and increase the damage caused by leaks. Also called ponding water, this is one of the most common roof problems across any roof’s lifespan. This extremely common issue can also be identified through regular maintenance with a professional roofing contractor.

Wind Damage

Wind can exert enormous amounts of uplift pressure on low slope roofing, and in drastic cases, can peel it off of the building. This is a major concern when designing commercial buildings, requiring calculations that take into account the building’s elevation and location, as well as local weather patterns. Of course, these calculations are based on a fully functioning roof.

Fatigue on mechanical fasteners and adhesives lowers uplift pressure resistance, making it easier for your roof to be damaged by storms. Your roof should always be inspected after any major storm, so peeling and broken areas can be fixed before water leaks into the building. Of all the most common flat roof problems, this is the issue that will most likely require emergency repairs. Failure isn’t just sudden, it can expose large areas of the building to moisture, leading to rapid degradation and mold growth.

Take the Headache Out of Flat Roof Leaks and More

TEMA Roofing Services can address every aspect of commercial flat roofs, including installation, repair and restoration. Our design-build services cover everything from planning and design to installation, giving you one trusted contact for the project (which can reduce total project time by as much as 33%).

Our team of professional roofers also handle roof asset management, which includes inspections, preventative maintenance and repairs that reduce the lifetime cost of your roof. With these services in place, you don’t have to worry about the condition of your roof. Give us a call today!