Son's "newbuild" (1919) has about 400mm of rockwool completely covering the loft space. Condensation is rife up there - the rafters are very damp and showing signs of mould already. I thought lofts had to be vented as well as insulated - although they are clearly conflicting requirements. Is this a common problem or is he just unlucky? Like many he has to dry washing indoors. Is there a cure? Thanks for any comments/practical advice.