It works fine here in Staffs.The fireproof layer can be fitted beneath the decor facade.It won't look quite as nice when it's clad in masterboard!!
Not quite. That will help compliance with Part b3 (structural fire protection) but won't meet the requirements of B4 (external fire spread) which limits the amount of combustible material on the surface of a building near a boundary.
Would you like me to scan you the spec'?
This is the spec' verbatim (inside to out) on a gable end less than 600mm from boundary...
100mm x 50mm stud gable.
9mm external ply.
6mm fire barrier i.e. 6mm particle board.
Membrane, battens, plastic cladding.
All passed and signed off April 2013. The specification was suggested by Trevor Edensor of Staffs BC. Do you want the address as well?