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Andrew Gabriel

In article . com,
writes:
Tony Bryer wrote:
On 20 Dec 2006 09:09:48 -0800 wrote :
In my previous house I used something called Limelite renovating
plaster for the first metre of brickwork that is usually hard rendered
by the damp proofing companies. It was lightweight and therefore there
was no condensation. It was also non-hygrospcopic unlike Carlite.
Sadly,the company don't seem to be around any more, although there are
similar products on the market, I believe.
Limelite is cement based, and should be avoided in these situations.
Whats needed is porous, so any damp can evaporate away. This means
lime plaster.

Breathability and porosity of cement based mortar depends on the
cement strength. At 1:6, there's no problem, but you need to add
a waterproofer to prevent the pores also wicking water through.
(Contrary to what you suggested, this won't work as tanking, as
any significant pressure of water will pass through the pores
regardless of their water repelling coating.)

genuinely breathable they will allow evaporation, which is enough to
keep most damp walls dry. To maintain this evaporation of any dampness
one should avoid non-porous coatings such as emulsion, instead using
distemper or similar.

Matt emulsion is breathable (vinyl isn't).

--
Andrew Gabriel