Joining Cast Iron to PVC
Posted by Chris on February 23, 2004 at 22:18:50:
I have a 4" CI stack from the roof down to just below the 1st floor joists that I can't remove with a major demolition project. It seems to be in pretty good condition, no rust streaks.

Below the 1st floor joists it turns horizontal for about 5', then goes vertical again down to the cellar floor. All of this section was rusted out, so I replaced it with plastic.

At the floor connection, the existing CI pipe has a hub, so I used one of those Fernco donuts (NOT a regular Fernco) that inserts into the hub, and the PVC pipe pushes into it. This seems to seal pretty tight.

At the other end, at the bottom of the CI stack, I've got a hub and couple of inches of plain CI projecting downward from the santee for the 1st floor toilet. The only thing I could think of to use here, to link up to my 4" PVC line, was a regular Fernco.

Does anyone have any other ideas? I suspect this isn't the code-approved solution, but I couldn't find anything else that would work. I tried a mission coupling, but the iron is sufficiently smaller than the plastic that the s/s band around the outside crimped.

Any suggestions that don't involve ripping out that 25 feet of CI stack would be greatly appreciated.


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