Make Sure Your Flat Roof is Pitch Perfect

A Wednesday evening varsity basketball game is nearly over when a strong storm quickly moves into the area. It begins to rain, then a sudden gust of wind violently peels the roof off the gymnasium. Debris pelts guests as they run for cover. As you turn your attention skyward, there’s nothing you can do but watch as thousands of gallons of rainwater pour into your building.

Many commercial buildings have large spanning roofs that are flat. The benefits include lower initial construction costs, architectural appeal, and needed space to mount mechanical systems. Some church, school, and college campuses may have buildings with flat roofs that cover hundreds of thousands of square feet of electronic equipment, books, students, worship services, instruments, gym floors, and more.

Since you can’t see a flat roof from the ground, problems like loose flashing or clogged drains may go unnoticed until it’s too late. That’s why routine inspection and maintenance are key to maximizing longevity and minimizing the potential for leaks and catastrophic failure.

Flat Roof Basics

A flat roof begins with the roof deck, a structural layer that transfers the external forces a roof creates (its own weight) or experiences (such as wind uplift) to the building. It can be mechanically attached, welded, or integrated (such as a poured concrete deck) to the framing. On top of the roof deck are several layers that make up the roofing system. These layers may include a vapor barrier, insulation, coverboard, and roof cover. The roof cover can be made of a variety of materials depending on the installed system. For example, a single ply membrane is made of a durable rubber or vinyl material, which can be attached by using adhesive, mechanical fasteners, or rocks known as ballast. This  layer protects your building against weather, including  water intrusion.

Flashing Red Flags

The perimeter edges of a flat roof are protected with a strip of metal or other material called flashing. It’s a critical component of the flat roof system and provides protection against wind and rain where the roof meets the walls. It also helps prevent wind from lifting the roof cover, which can lead to significant damage or even roof failure.

Regular inspection of the flashing can help you spot problems early so they can be fixed. “From the ground or from the roof with proper safety equipment, look for waviness, degradation, rusting, and disconnected fasteners. These are all red flags for flashing that could lead to a roof cover failure,” said Chris Cioffi, commercial programs manager for the Insurance Institute for Business & Home Safety (IBHS).

When flashing becomes loose, wind can cause the roof membrane to detach from the building, potentially leading to catastrophic failure and water damage. “Most roof related losses start with failure of flashing,” said Cioffi.

Maintaining a Flat Roof

The longevity of flat roofs can vary and is highly dependent on how it’s installed and maintained. Typically, a flat roof can last from 10 to 30 years. To maximize the longevity of a flat roof, it’s important to regularly perform inspections, cleaning, and repairs. Standing water, debris, and excessive wear and tear that’s not quickly repaired can all contribute to a roof covering that fails.

“Roofs should be inspected and maintained at every season change, before a storm, and following a storm. This way, if an issue is noted, it can be fixed before the next storm in order to reduce loss, including water intrusion and business interruption,” noted Cioffi.

Flat roofs often can’t be seen from the ground, so they require direct inspection. While they can be safer to inspect than a pitched roof, you’ll still need the appropriate safety equipment. As an alternative, you could use a drone to inspect the roof or hire a roofing specialist.

When hiring a contractor to perform routine inspection and maintenance on your roof, make sure they note the condition of the roofing assembly and indicate items that need immediate and near-term repair. Repairing small issues now can help prevent major problems in the future.

Routine maintenance maximizes longevity and avoids catastrophic failure.

1. It’s important to check the flashing around the perimeter of the roof. If it’s loose, get it fixed immediately. This is a common point of failure during high winds.

2. Check for debris like plants, balls, or items left by contractors. It’s common for HVAC vendors or maintenance staff to leave unused items on the roof, which can puncture the roofing membrane or become potential projectiles during high winds.

3. Flat roofs typically have several drains. Make sure they’re not blocked by debris. If the roof can’t drain properly, the standing water can lead to early failure of the roof covering.

4. You’ll want to check any equipment mounted on the roof to make sure it’s properly secured. Loose equipment or wires can damage the roof covering during high winds.

Additional Resources

Posted April 2023

The information provided in this article is intended to be helpful, but it does not constitute legal advice and is not a substitute for the advice from a licensed attorney in your area. We encourage you to regularly consult with a local attorney as part of your risk management program.