"ransley" wrote in message
...
On Jan 3, 9:07 am, "TKM" wrote:
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.

Is there a return in that room so that can recover some of the wasted
heat, is it a unit that uses outside air for combustion. How can you have
6" of wall insulation in 2x4 construction. 6" in the attic is only maybe R
21. I dont know where you live but R 21 is not much. My fire code specifys
5/8 drywall firecode x for any furnace room for the interior finish.


Good points. There is no system air return in the furnace room, so that's
an excellent idea.

The furnace uses outside air for combusion. The walls are 2x6 construction
as is the ceiling. 6" is the mimimum ceiling insulation thickness as the
roof meets the eave right above the furnace room. In other areas of the
ceiling, the insulation thickness is several inches more (as much as the
contractor could blow in). The drywall is 5/8". The furnace room door
(bathroom adjoining) is louvered. I leave that door open to increase air
circulation

What I think I'll do is put a small flexible vent pipe into the air return
plenum with the end of that pipe at the ceiling level. That will draw off
the hot air rising from the furnace and pipes. But, I'd still like to know
which insulation materials to use for those pipes and for another layer on
the ceiling. The ceiling material, of course, should meet fire code
requirements.

TKM