PVC Pipe Drain Clearance to Furnace/Boiler Flue Pipe

What clearance is required between a metal furnace vent into the chimney stack and the PVC Drain line?

I need to run a 4" horizontal drain just below where the chimney tie in and not sure how close is allowed. Normally I would keep it as far away as possible, but due to slope and height I need to stay as high up as possible with the drain line.

I've searched the forum and google but can't find a code clearance for this situation.

Appreciate the help.

Since single wall flue pipe requires a 6" clearance to combustible materials, I would expect that is the dimension is about what you would need to keep it from melting your PVC drain, unless you put some material between the two.

Thanks, I found similar info last night. I was looking for PVC clearances then I realized I would prob get more hits looking for Flue pipe clearances. Most places stat 6" like you said.

If I were to need to get closer, any recommendations on what to use to isolate/insulate the two.

If you can get it to stay in place, a piece of sheetrock is all you need.

I could def get sheetrock or anything else inbetween the two. I'm not opposed to boxing in the pipe with sheetrock or anything that would allow me to decrease the distance in between the two.

So if I boxed in the pipe with sheetrock or some other material that is listed as non-combustible then I can get closer to the pipe.

Is sheetrock sufficient or does anything else do the job better?(ie. cement board, insulation)

don't even need to box it. just a piece slipped between the two would be enough. insulation? no.