This is my first post, and I believe it may be a doozie!
My wife and I just bought a 1930 house that has been completely renovated inside in 2007, however the plastic tub surround was not installed properly and there was quite a bit of splitting of the silicone where the tub surround meets the tub. I expected to find some wall damage, but did not expect to find what I did. Upon cutting into the drywall (which is just plain old drywall) to remove it, I discovered the original lath and plaster walls are still behind the drywall! We removed the drywall layer about 3 feet up from the tub until the wall felt dry, and the walls behind the drywall look and feel to be in good shape. We do not want to get into tearing all the lath and plaster down to the studs and starting over even though that is probably what you all will suggest. I think we will just re drywall the cut out spots with greenboard and reinstall a new plastic tub surround. However, here is the big question that I have. The tub is on an outside wall, and the person that did this put a vapor barrier between the old plaster and the new drywall only on the outside wall and this was also the wettest of the 3 walls. Should this vapor barrier be there, or should I remove it and screw the drywall right to the plaster like the other two inside walls? Could I then use a vapor barrier primer on the greenboard to seal everything before installing the tub surround just to insure no future water penetration?
phew.. sorry this was so long, but I am at a loss and need help!