I took this picture of a damaged vent the other day. Notice how the PVC pipe is sticking through the lead at the top. In Florida and Southern states PVC is used, but your pipe may be black as ABS is used in many other states.
Regardless, if you see any of the pipe sticking out of the lead you have a leak. Critter Quitters will fix this. 
407-808-2501
info@critterquitter.com
