Can anybody help, I have purchased travertine tiles for my shower enclosure. I was advised to mount backer board to the wall before I tile, the problem is that the instructions say that the backer board can only be fixed to wooden studs in the wall but I have none only cardboard. Is it possible to either fix battens to the wall or remove the plaster board and cardboard oneside and construct a wooden frame glued to the other sides plaster board. I'm unsure how to tackle this.