Question about insulation around Class A pipe

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gdk84

Member
Feb 23, 2011
139
New England
Hello all
I'm having my upstairs bedroom finished off. The contractor is boxing in the class A pipe and I noticed insulation around it and pretty much right up to it as it exits the roof (paper faced bats) and he knows about the 1 inch clearance, etc. Its only R13 insulation. I'm planning on telling him, but im wondering why there is a square ceiling box between the first and second floor which maintains the clearance from insulation but nothing required as it passes thru the roof between the rafters. I understand that the box is where the double wall connects to the class A but why nothing when it goes out of the roof where there is gaurateed to be insulation? Nothing to keep insulation away. What do you think guys? Is this a big deal or am I over paranoid?

Chimney is Excel, intalled 2 years ago by dealer and second floor was not finished off at that time.
 
It's a big deal.
Insulation should usually be kept 2" or further back. This is usually accomplished by the assembly that goes through the 2nd floor ceiling - Fire stop and attic insulation shield.

Insulation is usually not up as high as the roof joists, so the flashing is usually good enough to hold it far back from anything.
 
So there is an attic insulation shield for this then? Right now there is nothing so no protection around it as it exites the roof.
 
Your contractor is doing it wrong if he doesn't provide the clearance to wood and insulation. It is not standard in our country to have insulation at the roof deck and if we did, it would be much better than R-13.
 
Pictures please so we get a better idea and not a wrong one! Cathedral ceiling? Or is this the 2nd story rooms ceiling?
 
These systems are designed to keep insulation away from the pipe using an attic insulation shield. Typically the ceiling deck has insulation on it, not the roof deck itself. So I am assuming that you have a story and a half? The upstairs is a cathedral ceiling and thus there is no attic?
In these situations a sheet metal shield should be made to insure that no insulation can come into contact with the chimney.
 
When this gets a proper insulation shield be sure the support box is vacuumed out completely. You don't want debris of any sort in there, especially if it's combustible.
 
Here is a pic. This place is a story and a half and built in the 40's. It is currently not occupied and I dont want to cut any corners, or have the contractor screw it up. If I had the time I'd do it myself so I know it was done correctly. As you can see, im talking about as it exits thru the roof.
 

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He just needs to make a sheet metal firestop/insulation shield. No big deal at all, it will only take a few minutes.
 
Ah, this is on the top side. Definitely keep the insulation a couple inches away. I know Excel says 1", but I would prefer an additional margin of safety for anything enclosed in a chase.
 
Maybe line it with durarock? If it were me id sleep better with 2" clearance to durarock or sheetmetal. Im no pro though! Its open now so get her right!
 
Nothing special is required here. It could even be framed with wood blocking, then insulate up to the blocking. As long as it has 2"s around it there is no problem.
 
Thanks everyone! I'll let him know!
 
Yes, 2" to wood is fine. After all, your roof sheathing is likely just barely 2" away from the pipe as that is all the bigger they make the cones on the roof flashing.
 
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