Question on chimney flues and insulation

Is insulation allowed around a chimney flue in the attic? I inspected a house today, there was no chase in the attic just the pre fab flue (do not know if it is 2 walled or not. Insulation was in contact with the flue. I wrote it up as need a specialist evaluation.

Next house today was an attic gas furnace and the vent pipe was surrounded by batt insulation stapled to the attic ceiling. Is that allowed since there is paper on the back side of batt insulation. Seems to me that it is a possible fire hazrd. Any comments please email

see pics

thanks in advance


furnace vent pipe.jpg

chimney attic flue.jpg


In my area, it is a violation.
The picture (#1) indicates to me that the pipe is at least a double wall (B vent type) pipe, but depending on the age, it could be a triple wall. The locking tab are a giveaway.
Insulation touching the vent pipe material of Fireplaces, Furnaces, Water Heaters, Range/Oven venting, etc. would be in violation and inspection would fail. County/Municipal C/I are tough on combustible materials touching or less than the Manuf’s instructions for clearance from the vent materials.
I’d right it up in my report, recommending action to correct.

First picture, what did it say on the sticker? Could very well be triple wall and ok.

Second picture, the paper backing (vapor barrier) should be removed when installed on the ceiling. This information is printed on the batts and makes a nice inspection picture.:smiley: