I’ve come across the following scenario several times. This is not a roof leak, but a drain component leak.
Above is a photo of a drain leak. Note the stains on the pipe insulation. Drain pipes are insulated to keep them from sweating.
This leak was caused by the connector piece that connects the roof drain bowl to the pipe. It’s typically called a No-Hub.
What you don’t see until you remove the no-hub, is the damaged rubber inside. Most of the time, this is not evident unless you remove it because it can be hard to see from the top.
Above you can see the damage to the no-hub from the roof side. This is not always possible. This particular roof drain is 10 inches in diameter, making it easier to see the problem.
My plumbing experts at Morrison Supply call this a CT Adapter. I replace all damaged No-Hubs I find with these because these are not covered with an aluminum jacket. So, hopefully, sometime in the future people will be able to readily see if there’s any damage.
Thanks for visiting.