DIY SOS Last Night - Lime and Sand plaster?

[Saeed]

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?

Kind regards,

Saeed

sr_ng 786

[Dave Jones]

Has the chimney been blocked up? Or still in use?

Dave Jones

[Saeed]

In message , Dave Jones writes

The chimney had lining (?) fitted all the way to the top as it's used for the gas heater. At the top the (I presume) stadard blocking off apart from a pipe thing sticking out has been done too.

The bit in the bedroom has had a ventilator fitted.

The house has been disused for about 2 years, and my mate reckons the absence of heat from the gas heater could have caused the damp build up.

Kind regards,

Saeed

sr_ng 786

[G&M]

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.

[Saeed]

In message , G&M writes

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.

[G&M]

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.

[mark]

In message , Saeed writes

More likely 'limelite' renovating plaster.

>I think I might have a similar problem on a chimney breast wall

Builders merchants.