5 Causes of Commercial Roof Leaks

contractors using torch on commercial roof

Any leak or moisture penetration problem on your commercial roof may cause serious damage to your building. We’ll outline the most common areas prone to roof leaks, how to identify them, and how to hire a commercial contractor.

1. Damaged perimeter flashing

Perhaps the most common area for commercial roofing leaks is the flashing. Exterior edges of the roof and interior parapet walls are protected by flashing that covers the roof membrane.

If flashing is improperly installed, cracks, or becomes loose due to high winds, the roof can become exposed.

This allows water and moisture to seep into the roof system and building. Roof systems expand and contract as the season's change, causing flashings to flex, tear, and break.

Keep a close eye out for damages to flashing systems, as they’re prone to leaks.

2. Clogged drainage

Commercial roofs need to have a proper drainage system to allow for water runoff. If water can’t drain, it pools and adds a significant strain to the roofing system. One square foot of ponding water weighs about 5 pounds per inch of water.

Drainage systems include gutters, drains, downspouts, and scuppers. Working together, these elements all allow water to drain away from flat roofing systems when operating correctly.

If a part of this system is damaged and can't perform its job properly, ponding water can cause:

  • Sagging of the roof from additional weight
  • Increased leaks
  • Build-up of moss and plants
  • Faster deterioration of the roofing system

Once you notice a problem with the drainage system, you should plan to fix it immediately.


3. Roof membrane damage

worker on commercial roof

Roofing membranes may crack, blister, split, or become punctured.

A compromised roofing membrane exposes the roof’s insulation to water penetration. Seeing that the membrane’s function is to prevent water from reaching the building’s interior, a split or blistered section quickly leads to leak problems.

Roof membrane cracks need to be addressed as soon as possible. If left untreated for long enough, even a thorough repair may not be enough to fix it. A complete replacement may be necessary if the tear is large enough and left untreated.

4. Open roof penetrations

Commercial roofs have many exterior mounted objects, including HVAC units, vents, pipes, hot stacks, gas lines, and any other item routed through the roofing membrane. These are classified as penetrations and are often the location of leaks due to the disruption of the roof’s membrane.

Roof penetrations must be secured properly to ensure the roofing system is protected from water penetration. 

As a business owner, it’s smart practice to routinely monitor these penetrations to ensure they’re watertight. Check the flashings, rain collars, pitch pans, and other sealants for any cracks or damages.


5. Age of the roofing system

Due to their size, commercial roofs have a limited lifespan before the elements and time start to catch up with them. They’re simply too big to remain completely problem-free for long.

Flat roofing systems, even when monitored correctly, begin to deteriorate drastically after about 15 years.

After about a decade, most of the symptoms listed above will have occurred. If the commercial roof is plagued with multiple problems, you may want to consider replacing the whole commercial system.

Often, commercial roof leaks require challenging repairs. If not performed correctly, minor problems will cause major economic headaches. Hometown Roofing Contractors helps customers identify qualified commercial roofers. Customers can research companies, request quotes, and see what other businesses have to say about their services.

Find a qualified commercial roofing contractor