Is it wise to install an elbow on the plumbing roof vent pipe to prevent debris or snow from entering? My vent pipe is insulated in the attic to prevent condensation.

Vents shall terminate straight up, no elbows above the roof line.

Most people simply place wire screening mesh over the top of the pipe, However, they do make vent caps,(see image) Regards, Tom

I would not worry about decris or snow unless you have trees directly overhead with very small leaves. An oak or maple leaf will never get inside a vent, most trees won't but I did find a dead bird in one vent some screening is the cheapest, most quick route