I live in northern Michigan, where ice dams are a problem.

I installed soffit vents and added a gable vent to keep the attic cold during winter. Part of the roof also has a ridge vent. (The roof has three gables and a section of shed roof.) My attic is pretty well insulated, and I'm ready to add more this fall. I also plan to add foam baffles to the roof near the eaves.

I upgraded to a high-efficiency furnace two years ago, and the PVC exhaust pipe goes right up through the roof. Is there a safe way to insulate that PVC pipe to help keep heat out of the attic? I've heard different opinions on this.