I live in Northern Canada where we get up to 3-4 ft of snow on our roof on a regular basis all winter. My vent pipe is about 12" high but it is always covered by snow. I put a 4 ft. piece of 4" ABS pipe over the vent stack to extend it above the snow. Is this method OK to use or it is overkill ? How does the stack vent properly if covered with snow? What about snow melting and leaking down into the normal stack height without the extension being used ? Any advice on this is appreciated.
Thanks
Greg... Ontario.. Canada.

I will assume you are talking about a sewer vent. Extending the vent is fine, you see this in CA mountains too.. How does it vent when snow covered? -Not well if snow is packed down. Snow melting is no different than rain falling down the vent, it goes into the main drain and then sewer or septic.

Different codes dictate the height of the roof vents. I live in Florida where our vents are at least 6" over the roof line. However we moved down from Wisconsin where the roof vents were 12". We didn't worry about the vents being covered by snow as the warm air from the vents melted the snow and sent it back down to the main, If you're concerned you could always cap your vents, (see image), Good luck, Tom