Plumbing vent flashing repair.

The improper use of an aluminum roof vent flashing to repair a leaking plumbing stack flashing on a steep slate roof.
This is a flashing made to fit on a pipe vent on an average pitch roof. Approximately 4/12 _ 6/12 pitch/rise.And usually used on an asphalt shingle roof. It is not a particularly good quality flashing.
The roofer had to push and bend down the aluminum flashing to fit the steeper pitch of the slate roof. This causes stress to the rubber/neoprene collar, both compressing the back side and pulling the front side away from the pipe. It has a rubber/neoprene collar that fits around the pipe. Depending on the quality of the rubber/neoprene, the collar may dry out and start to crack and leak in less than 15 years. It also has very small flange around the base of the flashing. The flange goes over the lower and under the side and upper slate or shingles. The smaller the flange the less protection from wind driven rain and snow.
You can see by the old shadow lines on the slate that the previous flashing was much larger.