I am in the process of buying a Victorian terraced house in Cumbria made of porous local stone. I want to fit internal wall insulation but have read conflicting advice about whether:
(a) the whole system should be breathable (using breathable membrane or no membrane) to avoid build up of condensation, or whether
(b) a waterproof membrane should applied immediately inside the stone wall to stop any moisture getting through.
Advice also differs about whether or not a ‘cavity’ should be left between the stone wall (with or without membrane) and the insulation to aid the building ‘breathing’.
Any advice would be much appreciated,