I bought an old house knowing that the copper pipes would have to be replaced because of freezing damage. The cast waste pipes mostly look fine; I suppose because they were big and empty at the crucial time. One vertical pipe has a small crack at the top — where it is wide and connects to the next length. Can this be repaired — with some sort of “worm clamp” — or does the pipe have to be replaced? And if replacement is the solution, should it be with cast or plastic? Cast will be quieter, won’t it? I won’t mind calling in a plumber, but I like to know what my options are — the house is worth it, but I have to count my pennies. Thanks!