Our daughter has moved into a converted flat. When I viewed the place with her I noticed there was polystyrene behind the wallpaper. The "builder" showing us round said: "Obviously thats there since we've cured the damp". Three weeks down the line the damp is anything but cured, their view is "Its condenstation", which reads like damp to me. Surely if a wall is damp the last thing you do is seal it in with something impermeable? If the damp was cured then why slap polystyrene on top?
BJ