I have heard twice now within the last few weeks that PVC and I am pretty sure I heard ABS are not acceptable for the exhaust systems anymore and as a inspector we should report on it not being correct material used. If this is true I just can’t seem to find any information on what pipe I should be looking for. Can somebody help me find something that I could do a study on this?
Where are you hearing this? And why are they going against the manufactures install specs?
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Not acceptable by whom? It appears to be widely used and accepted in my area on new builds. I see it in manufacturer installation instructions. No changes to code in my area that I am aware of. However, ABS has consistently not been acceptable, with exceptions.
Manufacturer installation instructions will have a schedule of acceptable materials and kits. Local AHJ often defer to the manufacturer.
Example from a 2026 American Standard NG furnace.
Apparently you’ve been listening to the wrong people.
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I was told it was the PVC specs, that it is only listed for DWV and not flue piping. I don’t know if what I heard is wrong or right I am just looking for clarifications, thanks Jeff
It sounds as if it’s PVC DWV piping specs, not listed for flu pipes and the glue connections will give out
I was told furnace manufacturers approve it for furnaces but not the piping specs
The only information I was told about the accepted pipe was it is black with orange lettering on it, he was not sure of piping name
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We’ll need a little more than that please. 
By who?
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I thumbs up your last comment, not sure why it has to be a red heart like it’s Valentine’s Day or something but I guess.
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The PVC is typically schedule 40 but the glue may be different. Depending on the specs by the manufacturer. Do a deep dive into an installation manual. I recommend you get very comfortable with them because this is where you will begin to spot important issues such as how to handle flue condensate etc.
There is so much information to take in, I don’t get how guys choose to change there careers, from driving a food truck to taking a few home inspection classes and then all of the sudden they are busy home inspectors
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That video is 6 years old. I have not seen that pipe requirement change in my area. Though I appreciate the conversation about the pipe degrading.
Apparently, some municipalities have a UL 1738 compliance requirement, which is what that black pipe is in the video.
Good post and good information.
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lol your right the video was 6 years old, I scanned through the links you just shared, I will take more time to read into them soon, thank you Brian.
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in 2016 we found out in wv that mchm, a chemical used to get the sulfur off of coal and really toxic that smells like red twizzlers, completely dissolves the glue holding plastic (all types, pvc, cpvc, abs, etc) pipes together when the water company tried to kill 300k of us by choosing profits over safety during an mchm spill.
Thank you Greg.
The pipe degradation is good information.
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Did you watch his video? And my subsequent UL 1738 information? It is interesting.
And I agree, as long as the manufacturer and the AHJ allows or calls for schedule 40 PVC then there is nothing to report. (unless of course the pipe material is degraded or some other defect present)
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Wow that’s crazy, they must have never tested it before use