Removing sand/cement plaster

[Bitstreams]

Our dining room has salts breaking up the facing plaster. I've hacked off a test area of the plaster and found that the first 1m of wall underneath has a very hard sand/cement plaster underneath. This is extremely hard.

Above it I can remove the plaster easily and get back to the stone/ rubble walls. Is there any prospect of me being able to get the sand/ cement plaster off (have tried a cold chisel and lump hammer so far).

The original plan was to remove the plaster and use a traditional lime- based plaster with good salt-holding properties.

Simon

[Mark]

Sounds to me like there has been a dpc installed and the usual requirement is to cement/sand render a metre up the wall. If so, I would imagine that hacking off the render will invalidate the warranty. If you do want to hack off the render a heavy SDS drill which accepts chisels will make things easier.

mark

[Maris]

You should be able to get the render off with a cold chisel and lump hammer. It's hard work I know. I'm doing as similar thing here. And yes, I intend to replace it with a lightweight plaster but not necessarily lime based.

Maris

[mail]

Dear Simon The other posts are right It is a dpc render with or without guarantee and most are pretty worthless unless covered by GPI or GPT

I question the need to get rid of it IF it is a good 3:1 render why not leave it on? and do what you want over the top - whatever that is?

To determine if is good 3:1 you can have it tested or an experienced person can tell pretty well - chances are that if it is as strong as you say it will be water proof and the problems you have been having will be associated with subsequent plaster (Gypsum backing, browning, bonding or skim) - Take all that off and get a damp meter and measure the render at daily intervals and see if it is drying out

No lime render I have ever known has salt retardant properties or can indeed be made to have - I may be wrong. What it does is breathe and if there is rising damp with salts you will eventually get hygroscopic salt deposition - or more likely your children as it takes a long time under most circumstances Chris

[Bitstreams]

I think, having mulled this since yesterday and now that I've stopped having a grump, that the 'hard' plaster is the result of a DPC or similar going in at some stage.

My inclination, therefore, is to leave it in place and realise (too late) that I have used completely the wrong finishing plaster over the top. I used Wickes One Coat and then skimmed Thistle Multi Finish over the top - both a Gypsum based and I should have used something else - maybe a lime render?? What surprised me was just how fast the salts reappeared - only a few days in fact.

A good contact at a natural materials firms says they do a natural breathable plaster that has a cell structure that traps the salts - but it needs to be 20mm thick to be effective, which would mean hacking off the hard plaster. What would/could I use instead as a plaster and would I do it in one coat - I'm not sure what Lime render looks like.

Simon