# Fiberglass Insulation Against Vent Pipe



## ckdeuce (Feb 15, 2008)

Is it safe to put insulation against double wall pipe that runs through the attic.  I understand that fiberglass insulation in non combustible as long as it is not the paper-backed type.  Any issues with it touching the vent?

Thanks


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## grizzly2 (Feb 15, 2008)

I have had exactly the installation you describe, for 30 years of wood burning in my home.  fiberglass insulation is indeed glass. My insulation touches the Metal Vent insulated double wall pipe. The sticker on the pipe, still just ledgable, says 2" clearance to combustables, and doesn't mention non combustables at all. 

I would be more conceraned about insulating right up to a single wall pipe. The fiberglass won't burn, but I wonder if that area of the pipe could get too hot.


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## stoveguy13 (Feb 15, 2008)

need to keep the insulation of the chimney it should maintain the 2" air space around the pipe


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## jtp10181 (Feb 16, 2008)

Pipe clearances are AIR SPACE clearances. Also fiberglass insulation is NOT a listed non-combustible.


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## ckdeuce (Feb 16, 2008)

jtp10181 said:
			
		

> Pipe clearances are AIR SPACE clearances. Also fiberglass insulation is NOT a listed non-combustible.



[edit] Types
Rock and slag wool. Usually made from rock (basalt, diabase) or iron ore blast furnace slag. Some rock wool contains recycled glass. Nonflammable. [7] 
Fiberglass. Made from molten glass, usually with 20% to 30% recycled industrial waste and post-consumer content. Nonflammable, except for the facing (if present). Sometimes, the manufacturer modifies the facing so that it is fire-resistant. Some fiberglass is unfaced, some is paper-faced with a thin layer of asphalt, and some is foil-faced. Paper-faced batts are vapor retarders, not vapor barriers. Foil-faced batts are vapor barriers. The vapor barrier must face the proper direction. 

I have read multiple articals that say fiberglass insulation (non paper backed) is indeed non-combustible.  Can you provide anything that says to the contrary?  Honest question....  As I am concerned.  I appreciate your help JP, just want to know for sure.  Again thanks.


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## stoveguy13 (Feb 16, 2008)

what kind of pipe are you installing i can tell you superpro /supervent make a attic insullation shield that is made to keep the insullation of the pipe and if there is not enough space in the attic to allow for the attic shield the chimney must maintain a 2 inch air gap around it.the instruction for the chimney pipe should tell what you need. to do and maintain for space.


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## ckdeuce (Feb 16, 2008)

stoveguy13 said:
			
		

> what kind of pipe are you installing i can tell you superpro /supervent make a attic insullation shield that is made to keep the insullation of the pipe and if there is not enough space in the attic to allow for the attic shield the chimney must maintain a 2 inch air gap around it.the instruction for the chimney pipe should tell what you need. to do and maintain for space.



The pipe was already installed in the home.  It is Hart and Cooley Double wall class-A.  I noticed that there was not enough clearance between the pipe and the wall where it went through a closet.  I went into the attic to cut out some addtional clearance and notice that they had run the insulation right against the pipe.  After I cut the hole to allow a true 2" clearance I was going to put the isulation back.  The pipe states 2" minumin clearance from cumbustibles.  It has always been against the pipe, and I have read that insulation is not a combustible material.  The pipe gets warm to touch during a hot fire, nothing that would light a match let alone paper or insulation.  But I imagine in case of a chimnet fire, the clearance from cumbustibles is needed.  If i dont run the insulation, I will get a nasty clod draft.  But I want to be safe.  Thanks all...


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## stoveguy13 (Feb 16, 2008)

when you pass through a floor there shoud be a firestop in place which should fill most of the gap around the pipe i think hart and cooley are still in buisness you may want to see if you can find the a firestop for it i would maintain the the two inch airspace with the insullation.


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## ckdeuce (Feb 16, 2008)

I appreciate the info.  I am going to just replace the whole thing,  I have also found out that the only support holding the whole thing up is the collar that holds it in place at the basement level.  There is no other support going the whole way up.  So basicaly, if that bottom support comes lose or fails.....  I'm going to have a bunch of double wall pipe on the floor of my basement......  And I have no need for that!  Hate when others cut corners and I have to deal with it!


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## SlyFerret (Feb 16, 2008)

Get the insulation off the pipe.  Use an attic insulation shield to maintain proper clearances if you need one.

-SF


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## jtp10181 (Feb 16, 2008)

Clips from some manuals

_DO NOT pack insulation or other combustibles:
between ceiling fi restops; between chimney
and attic insulation shield._

_Failure to keep insulation or other material away from chimney
pipe may cause fi re._

_Non-Combustible Materials Specifi cation
Material which will not ignite and burn. Such materials are
those consisting entirely of steel, iron, brick, tile, concrete,
slate, glass or plasters, or any combination thereof.
Materials that are reported as passing ASTM E 136,
Standard Test Method for Behavior of Materials in a
Vertical Tube Furnace at 750ºC, shall be considered
non-combustible materials._

FYI Fiberglass batting does not meet ASTM E 136

I never said fiberglass insulation was combustible, I just said it is not a LISTED non-combustible.


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