-
Against an outer wall? In which case, yes.
I built a 2x2 stud wall against the outer wall, with a 2 inch ventilation gap (I've also put a few airbricks to the outside), insulated with sheep wool and then foil-backed plasterboard.
I'm blithely not considering any possible regs.
I considered using more breathable / traditional materials (wood wool board, lime plaster etc...), but realised that with an air gap, that wasn't necessary, and finishing would have been a drag.
Anyone installed internal wall insulation in a Victorian brick building? I'm still deliberating methods and am at a loss between insulated plasterboard/PIR or wooden fibre board. Considering DIY as my money is fast disappearing on other renovations.
Do I need to meet regs with certain U values? Seems wooden board will not manage this.