Dear all,
A friend of mine has had a couple of solid walls internally insulated with a stud wall and small cavity. I don't know much more about the structure used, but they later decided to ventilate the cavity into the house at several places around the skirting boards! Everything I have read suggests that this is a complete error, and that the cavity should have been ventilated to the outside. The contractor may have used sheeps wool for a breathing wall, but even so I think you still have to maintain the integrity of a semi-permeable membrane. Is there any situation where this makes sense?
Many thanks.