I have an attic bedroom. I have pulled down the existing plaster and
> lathe wall seperating the bedroom from the small roof space (where the
> roof is too low for the room, you know the part nearest the
> guttering). The wall is approx 1.3 metres high.
>
> I am going to put some rockwool insulation on the roofspace side of
> the new plasterboard I am putting up. My question is, not I need a
> vapour block between the plasterboard and the rockwool? Or will the
> partial airiness (from between the roof slates) make this unnecesary
> as the moisture with evaporate from the rockwool. I am thinking I wont
> need it as this situation is virtually identical to using rockwool in
> an unconverted attic (but of course on a wall).
>
> Thanks in advance for any replies.
>
> James
If the eaves space is dry and well ventilated, then you shouldn't need anything else there. If you intend to board up the back and front of the partition wall, with lagging in between, then you would need some sort of moisture barrier to stop the warm moist air in the room itself from damaging the walls.
Try using foil backed plaster board instead.