I have an 80 year old house that has developed cracks and holes in the cast iron stack. As well, the 3" copper horizontal run to the toilet has developed numerous holes, that I have temporarily patched with epoxy.
Given the fact that almost all interior walls accessing the stack have been opened for access, I WAS planning to replace the entire drain system in ABS (at least to the basement floor, and perhaps even the ground works to the footing). Once I repair the walls (lathe and plaster) I really don't ever want to ever need to go back in there again.
There is no doubt I will be replacing the short horizontal run with ABS, however, with regards to the stack itself, one plumber has recommended only replacing the sections that are cracked or have holes (approximately 8 ft).
Question: What is the normal lifespan of cast iron drains (ie. am I needlessly replacing more than necessary)? Advice would be appreciated.