Roof Flashing for a Pipe
The flashing where a flue or vent passes through a pitched roof: the base plate on the slope with its hole, and the sleeve cut to the pitch. The flashing where a flue, vent or exhaust pipe passes through a pitched roof: a flat base plate on the slope with the hole cut to it, and an upstand sleeve, straight or narrowing to the pipe, cut to the pitch at its foot.
How the roof flashing for a pipe is developed, with a worked example · Pipe ends and nozzles