I am in desperate need of some good tile advise. This may seem long winded , but it has really developed into a serious problem for me and my husband. First of all, the weekend we moved into our house my husband, while straightening the gooseneck under the sink in the bathroom, accidentally stuck his finger right through the pipe!! Little did we know what a project this would start. First of all we called a plumber who had to replace all of the plumbing in our bathroom to bring it up to code once he fixed the rotted areas. In the process he has to drill into the plaster in many areas and knocked down many of the plastic tiles. The removal of them was going to be a later project, but we now had no choice. Now we are stuck with what to do. We want to tile, but cannot get a straight answer as to what we should do for waterproof underlayment. One gentleman at a well know home improvement store told us to put the backerboard directly over the plaster, attaching it with a layer of mortar and apporiate screws into the stud. Then we can set our tile. Another gentleman at the same store told us that if we did this we would rot out our wall and we need to remove the plaster and attach the backerboard directly to the studs. This is a bit more difficult since we have a 1910 home and plaster precedes wood lats which are then attached to the studs. In addition, removing plaster is not as easy as he thinks it is ( He said plaster is the type of materieal you can stick your elbow through!!!! Well, the plaster on my walls is more like cement and I am pretty strong but I can't stick my elbow through it or never would I be so stupid to try). What do I need to do...please help!!! We currently have removed the plastic tiles and used harsh chemicals to get all the glue off down to a level plaster surface. Please give me any advise you can!!