Membrane roofs are extremely durable and reliable, but when they leak, it’s often because of something that weighs just a few grams, like a simple sheet metal screw.
In our experience, HVAC service often precedes a leak. That’s because servicing a rooftop HVAC unit requires removing a door to get inside of the unit. The door is held in place by sharp sheet metal screws. HVAC technicians will often drop the old corroded screws and leave them on the roof, reinstalling the door with new screws. As soon as someone steps on those screws, they can create leaks.