Originally Posted by
Kevin Barre
It's a flat base flashing (made to the correct pitch) with the vertical section carefully soldered to it. While it obviously took a lot of time to make, I suspect it was made locally
Which would mean it was not a listed flashing for use with a Type B gas vent.
I believe those are required to turn up a certain amount and have a storm collar (thinking to what they look like at the top of a chimney, and, if that was not an approved flashing, it should at least meet those requirements). Wind moving that thing around is going to break soldered joints apart.