We have a small porch type extension, built from a single pay of brick. In winter get a small amoutn of damp coming through, and mould on any cloats left hanging there.

Is there something I can treat the plaster with to keep the moisture out?

cheers

Your best to fix lats to wall , makeing a small air break , then plasterboard and skim , and fit a air brick to outer skin .

As Alan says, dry line it for best results. For a quick solution you could try THIS (http://www.thermilate.co.uk/insulating_paint_additive.shtml) paint addative.

Dont stick boards to your wall , As the damp will come though,

cheers
I'll try the paint, if is still comes through I'll dry line it

you could use `liquid plastics K501` to seal the brickwork from the outside hence preventing any water getting through to the inside. It doesnt discolour the brickwork and wont look like you`ve done anything to the bricks but works brilliantly.

http://www.liquidplastics.co.uk/Product.asp?id=163

Try Thompsons Water seal It Does Exactly What It Says On The Tin :lol1:
seriously tho theres all sorts of stuff at B&Q to do this

think about it like this,you dont tile a roof on the underside of the rafters to stop the rain.so why try and waterproof the inside when you should be doing the outside.(obviously there are exceptions,like basements etc):D