I was confronted with the dreaded laminate Pb wall a few years back. Think it was 2 9mm boards with something like 20mm board in the middle. Pissy wood frame around the edges, nothing running vertically in the middle.
It was all coming apart, but the lounge was on the other side and all well papered. Carefully removed the layers leaving one 9mm wall papered wall, dabbed the middle layer back on then bonded osb on, before tile backer boards. No room to build a stud frame as bathroom was tiny and there was a wall hung basin to be fitted and grab rails.
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