"Saeed" wrote in message
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In message , G&M
writes

"Saeed" wrote in message
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The DIY SOS on BBC last night showed a house in Bradford where one of
the problems was demp in the walls.

One of the crew said the damp was caused by the "wrong sort of plaster
not allowing the wall to breathe". They remedied it by replastering
using (I think) "Lime and Sand Plaster".

I think I might have a similar problem on a chimney breast wall
(terrace
house, so not an external wall). The wall has around 2 inches of
plaster
(browning undercoats and top finish). I question the need for quite so
much plaster. The plaster was all the way to the stone flagged floor,
with a cellar underneath. Last year I hacked off around 2 inches at the
bottom all along the wall, and this help, but not entirely, and last
nights show gave me another clue.

Anyone know what this plaster is, and where to get it from?

You have to make it yourself from 5 parts (roughly) sharp sand to 1 part
lime putty. You either buy lime putty made up in 30kg tubs or mix it
yourself with a 25kg sack of hydrated lime in a dustbin and leave for a
few
weeks (or longer if you can). Then mix and stir until it forms a really
smooth paste. You then have about three weeks to put it on the wall so
unlike gypsum there's no rush to get it right. Use the same tools as
normal
plaster but damped the plaster with a spray daily to stop it cracking as
it
dries.

Experts add hair to the plaster as well to give it more strength, though
we've found it okay as is. You then need to paint with a breathable
paint,
or use limewash - the milky bit left on top of the lime.



All when and good, but the stuff they used on last nights show was mixed
there and then and it dried within a day. I also got the impression got
ready mixed (sand and lime) in pre-packed bags and just added water and
whisk.

Ah, that's hydraulic lime then. Sets much faster. You use it just like
cement based plasters. You can buy it ready mixed but I don't know the
brands as I use lime putty from a local supplier. Search for "hydraulic
lime plaster" on google.