Cast iron vs PVC sanity check

Hi all

Quick question for the board - I'm a homeowner hiring out for a substantial second floor rehab project in a 100+ year old house that includes some plumbing. In general I do my own plumbing or hire plumbers and this company is new to me. Part of the project includes relocating some fixtures and tieing into the existing drainage system, which is a 4" cast iron main stack and a 2" stack connecting two sinks to a catch basin. Both PVC and cast iron are code approved for my house type and location.

Short question: Is there any reason to preemptively replace the stacks with PVC? The workers want to do that and for the moment I have told them not to - I have always preferred cast iron due to the noise considerations, and although the stacks are quite old there are no obvious defects, and the times I have cut them to insert a tee they have seemed quite sound. The workers main reason for replacing the stacks is their age.

Am I on the wrong path here? Should I consider replacement for either of the stacks?

Thanks in advance

Paul

I'm not an expert, don't play one on TV, and didn't even stay in a Holiday Inn Express last night. But in my (limited) experience, plumbers seem to prefer NOT to replace CI stacks unless absolutely necessary. If the joints are good, and there's no cracks, misalignment, settling, whatever, the guys I've used have all said to leave it alone. HOWEVER, I would inspect it VERY carefully to check for anything remotely suspicious: it'll be a lot easier to fix it now than later!

c.

Horizontal sections and underground bits might be suspect and if you are tearing things up underground, probably a good idea. Aboveground...don't know. Wait for some pros thoughts.

I have replaced split vertical sections of CI in homes that were built in the 40s.

If yours was built turn of the century the plumbing system is much older.

It may or may not be in good shape but if I were in your shoes I would replace the stack, and any other lines that are accessible, the stack can be replaced with CI.

I would hate to do a large remodel and after completion have to tear out walls to replace something I should have done in the first place.

I agree, replace it while it's open. Chances are it's fine but why take the chance?

You can replace the stack with cast iron again, or you could do the whole system in cast iron. If I ever re-do my own house I will be doing it in cast iron no-hub. It's quiet and should until long after I'm gone.

I've replaced cast iron horizontal pipe that was less than 30 years old and had failed for its entire length. It's overrated. The quality of cast iron depends on which foundry it came from, what time frame it was made in, what type it is, and so on.

There is a different set of skills necessary for PVC - for example, allowing for more expansion and contraction. And if the noise bothers you, insulate around the pipe with fiberglas insulation. Make sure that the pipe has no slivers or rubs tightly on wood before covering so that expansion and contraction don't transmit noise like a phonograph needle.

If the stacks seem to be in good shape and are well-supported, I don't see a need to replace them. If, as you say, they've been cut several places for tees, I'd worry a bit. (Unless they're cast iron tees . . .) Remember, a cast iron stack can easily weigh hundreds of pounds.

Thanks for all the advice. We're going to replace the smaller stack which is in questionable shape. The bigger stack appears to be in solid condition and we'll likely leave the vertical portion if a close inspection doesn't find any problems. If it becomes an issue in the future the stack is accessible without a lot of deconstruction (exposed in the basement and behind a simple drywalled chase on the first floor).

cast iron

Without reading the voluminous previous replies, my suggestion is that portions of cast iron that have water flowing through them usually do not deteriorate. The pipes that do deteriorate and crack are usually the vent portions above the plumbing that are only exposed to humid air. How old are you? Using their argument, maybe someone will want to replace you.