Using tile backer foam board for internal walling of single skin block wall.

[JohnLeeWall]

I am curios if this is doable or would work. I have a small single skin block shed. Now I am wondering if you can use foam tile backer board like Q Board dot and dabbed to the wall as both the vapor barrier, insulation and paneling without using plasterboard? This panel is meant for wet rooms and is meant to be water tight so my thinking was that it would stop vapor penetration getting into the wall and hitting the cold surface, give some insulation (30mm thick) with a small gap behind the board and also give a nice strong surface that cannot be attacked by mold unlike plasterboard. Would this work? or would wooden battens, insulation between, vcl then plasterboard be better? The building exterior skin will be rendered also in a silicone based render to stop moisture ingress if this helps and I have a nice roof overhang to stop water leaking down the sides of the building. Any ideas are welcome.

 

[Swwils]

You can get insulated plasterboard that actually is vapour check.

Take care as most building suppliers do not know the difference and think any amount of vapour resistance is a vapour barrier.