Looking to buy a co-op in older building. Unit was renovated by previous owner, but they didn't get a good plumber - kitchen sinks are unvented, bathroom sinks may be unvented, and waste pipes will need replacement. I'm completely new at this - how big a job am I getting myself into, and how long might it take to bring everything up to code? Thanks for any info you can give.

The vents shouldn't present much of a hassle if the unit's located on the top floor. Walls will have to be opened up, pipes torn out and replaced, vents run out the roof or revented back in the attic to a dry vent. All major surgery involving more then one trade. Before you close, or even make a offer, get at least three estimates on bringing the building up to code. If the plumbing is that bad I would start to be concerned about the wiring. Get a inspection on the building and make your decision from the report. Good luck, Tom