Commercial Flat Roof Leaks: Top 8 Leak Sources on TPO & EPDM
Running a business is stressful enough without water dripping onto your inventory, employees, or customers. Flat roofs are the standard for commercial buildings, and the two most common materials used are TPO (a white, reflective membrane) and EPDM (a durable black rubber).
While both of these systems are incredibly tough, they are not invincible. When a commercial flat roof starts leaking, it is rarely a mystery. The water is almost always finding its way in through one of these eight common failure points.
1. Punctures and Membrane Tears
Flat roofs see a lot more foot traffic than residential shingle roofs. HVAC technicians, electricians, and maintenance crews are constantly walking across the surface to service equipment. A dropped tool, a dragged heavy metal panel, or even a sharp rock caught in the tread of a work boot can puncture the membrane. Once the surface is pierced, water has a direct path to the insulation below.
2. Failing Seams
Commercial roofs are rolled out in large sheets and joined together. TPO seams are heat welded, while EPDM seams are typically glued with specialized adhesives. Over time, extreme temperature fluctuations cause the building to shift and the membrane to expand and contract. This constant movement can eventually cause those seams to pull apart, creating a massive entry point for water.
3. Blocked Roof Drains and Scuppers
Because flat roofs do not have a steep pitch to shed water naturally, they rely on internal drains and scuppers (openings cut into the parapet walls) to move water off the roof. If these drains become clogged with leaves, plastic bags, or debris, the water has nowhere to go. It will simply pool up and search for a way inside.
4. Ponding Water
This ties directly into blocked drains but can also be caused by crushed underlying insulation. If water sits on your roof for more than 48 hours after a rainstorm, the industry classifies it as "ponding water." The immense weight of this standing water will degrade the roofing membrane much faster than normal and will actively exploit even the tiniest microscopic pinhole.
5. Deteriorated Flashing on Parapet Walls
The edges of your roof where the flat surface meets the vertical parapet walls are highly vulnerable. Metal flashing is used to pin the membrane to the wall. If this metal rusts, pulls away from the masonry, or loses its protective caulking, rainwater will run right down the wall and behind the entire roofing system.
6. Pitch Pans and Roof Penetrations
Every pipe, vent, and HVAC curb sticking out of your roof is a potential leak source. Pitch pans are metal boxes built around these penetrations and filled with a pourable sealant to keep water out. Over years of UV exposure, this sealant dries out, cracks, and shrinks. Failing penetration seals are one of the most common reasons facility managers call us for a roof leak repair.
7. Membrane Shrinkage (Specifically EPDM)
EPDM rubber is known for its durability, but older rubber roofs are notorious for shrinking as they age and bake in the summer sun. As the rubber sheet pulls inward, it creates immense tension on the seams and the wall flashing. Eventually, the membrane will pull completely away from the walls, exposing the sensitive interior layers to the elements.
8. Age and UV Degradation
Nothing lasts forever. If your commercial roofing system is approaching 20 years old, the protective top layer has likely been worn away by UV rays and severe weather. The membrane becomes brittle, chalky, and prone to cracking under normal thermal shock. Depending on the building design, some property owners may even choose to upgrade sloped architectural sections to metal roofing to completely eliminate future membrane wear in those areas.
Protect Your Business and Bottom Line
A leaking commercial roof can disrupt operations, damage expensive equipment, and create serious liability risks. At True North Roofing, we understand that time is money for your business. We perform thorough inspections to identify these failure points before they become a crisis.
If you are facing a major capital expense for a full replacement, we offer tailored financing options to help you manage cash flow while protecting your facility.
Ready to secure your building? Reach out to schedule your inspection today and let our experts handle the rest.
Serving Our Local Communities:
Asheville & Buncombe County
Hendersonville & Henderson County
Waynesville & Haywood County
Brevard & Transylvania County
Sylva & Jackson County
