I am purchasing a house, and the main stack is copper. The inspector nored that the seal to the Cast at the floor needed to be redone, and there were a couple joints that showed signs of having leaked previously near the top. The like is 4" cast, to a 3" copper up to the various joints. The rest of it looks good. The bathrooms (1.5ba) both are re-done, so they won't be worked on for a while, so getting all the way to the second floor would be a pain right now if I were to replace all of it.
We do have future plans of adding a second master bath, and maybe re-doing the main bath, but not for 5-10 years at this point.
Should I either:
1) fix the issues and let it be for now.
2) replace from the cast to the ceiling in the basement with 4" PVC and connect original copper back
3) replace everything
Obviously, I don't want to, nor plan to do option 3 at this time, but figured it should be included. I am not well versed in connecting different type of pipe together and what is allowed or not. I've only used PVC in the past.
Here is a picture of the stack. To the upper left is the 1/2 bath, to the upper right is the 2nd floor bath, and the kitchen. Bottom right is laundry/utility sink. The area of the previous leaks are to the left of where the sink connection enters the 3"
I would fix the issues for now, I would never get rid of that copper, that is a rare find and it looks good. If you know how to solder and have a large torch you should keep the copper. Man were talking big bucks for that stuff.