Thanks for info. went to BG site and phoned.
Adhesive will not work on foil backed boards was answer.
Could do what you suggested.
On thinking about it I may be able to get away with standard 12mm boards as there will be a slight gap between the wall surface and boards which will stop...
As it was a garage I am surprised it did not have a 1hr fire rating to the studwork in the first place.
The block work is to stop fire spreading in either direction.
The insulation does not protect the studwork.
I need to cover a wall in an old property where the wall has been saturated with salt from hanging bacon sides :D
I have sealed the area and now want to cover the whole wall with foil backed plasterboard.
As it is the hallway and the stairs come into play I do not want to batten out...