I am wondering if such a thing exists? We have a low pitch roof so hard attic access and after months of chasing a roof leak, it now appears it could be caused not by the flashing, but by a connection in our waste stack vent that when it rains hits this connection and drips gradually out just above our ceiling in an area of our attic we can't reach. The only way to fix this correctly would be a major mess involving either cutting a beam to access it from the attic or tearing out our bathroom ceiling so I wondered if I could instead fit a PVC/ABS 180 degree elbow on the top of the vent on our roof or if that would be super bad from a sewer gas standpoint. Currently, I have a soup can with a gutter screen holding it up a little so it will vent.