Is this vent too close to combustibles?

While checking a low-efficiency furnace I noticed that where the vent went through the ceiling it was in contact with the drywall (photo 1). In the attic, the same vent was also really close to the sheathing, maybe even touching (photo 2). But in neither case was there any discoloration.
Would anyone call that out? If so, minor, moderate, or major?
I’m leaning towards stating in the report that I’m not sure, and to have the HVAC guy check that out while he’s there servicing it for the other issues (very dirty, and kill switch missing).


6" for single wall and 1" for double wall.


I could not find markings on the vent indicating the type, and I don’t yet know how to tell the difference by sight. (Any hints would be appreciated.)

You have double wall going through the ceiling. Single wall is tied into the collar.

If you are having trouble deciphering, go to your local big box home improvement store and look at the pipe and fittings.


Looks like a B vent going through the ceiling from here. Needs a minimum of 1" Clearance. Can’t tell what is going through the roof based on the picture, but would think it is a B vent also. What did it look like above the roof?


Roof was too steep to walk. Didn’t see topside where the vent penetrated.
Thank you fellas

You could see the penetration through the attic space. This is an important place to inspect as sheathing or shingles may be in close proximity to the flue pipe.

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Don’t forget to check the for the 1 inch clearance with the insulation also. I would recommend a insulation baffle to ensure the proper 1 inch clearance. I can’t see in the photo, but hopefully a little helpful tip.