Tiling on plasterboard - pva'd shower walls, can I sand it off or do I have to replace the plasterboard?

Hi PVA is considered "old school" the apparent issue with PVA is that when wet, loses its stick so to speak and tiles would eventually fall away. If you are going to tank over it and then tile I don't see that there would be such a problem as the tanking solution should be water proof preventing moisture reaching the PVA. If the issue is that the tanking solution will not adhere to the PVA then you have answered your own question, but if you do resort to removing the plasterboard then replace with a tile backer board better job all round Hope this is of some help Steve