DIY Doctor UK DIY Forums

I want to fix plasterboard with insulation attached ('crunchy board'?) on to a single skin external brick wall using the dot and dab (?) method. The wall does had some damp coming in from outside which I have treated externally with Thompson's Water Seal.

Should I treat the inside surface of the brick wall with some sort of waterproofing before sticking on the plasterboard given that I can't use an internal polythene layer? Would this cause problems with condensation?

If I should/can waterproof, what product should/can I use? Is there one that is breathable?

Any help gratefully received.

Thanks

elkie,
If the room is to be used for domestic purposes you must form a ventilated cavity between the outer wall and the lining. Sticking foam backed plasterboard direct into the wall will soon give condensation problems with water coming out at the lower edge of the plasterboard.
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