What kind of insulation materials should I use to insulate the hot-air pipes
and ceiling in a furnace room?

The house is about 5 years old with 6 inches of blown-in cellulose
insulation in the walls and ceilings. The furnace room is on the second
floor and has a finished drywall ceiling and walls. But the room is very
warm during the winter and snow on the roof above the furnace room melts
before the snow on the rest of the roof.

I've sealed the furnace pipe joints with mastic to stop hot-air leaks; but
now I'd like to wrap the pipes with insulation and add a layer of ceiling
insulation inside the room and maybe the outside wall too.

TKM