Removing damp plaster and replacing

[eddieed]

So before we start I need to explain that we have tried to find the cause of the damp which we believe to be caused by next door, however even with Surveyors, insurance companies etc involved they completely deny it as it hasn't been too bad we have just ignored it, but now we want to decorate our bathroom so it needs sorting out.

Firstly the issue is odd, the damp is about half a metre square in the middle of the wall. An independent damp expert believes that it may be caused by excess salts in the brickwork caused by animals being kept in the barn that was converted, specifically horses, not sure where the moisture is coming from (I still think next door) but as it is a bathroom on both sides it could just be moisture in the air. The wall is not damp above, below to the left or right of this area!

So I am ready to remove the damaged damp plaster. what should I do to replace. I was thinking either a waterproof cement render and then skim or attaching a waterproof cement board to the wall and then skimming over. Anything I can put on the bear brickwork prior to the cement render to help or any other suggestions.

I have got to the end of my tether with trying to get next doors input so just want to solve the decorating issue now. I know the underlying cause should be solved but I will leave that for 5 years time when I rip the bathrrom out completely!

Thanks in advance.

 

[ree]

If moisture is penetrating the backing/wall on a continuous basis then it will eventually manifest on the interior surface, no matter the material.

So you should find the cause(s) before any remedial treatment.

I have no experience with animal urine soaked masonry but some published remedies seem to involve replacing the masonry. Its a modern difficulty with all the farm building change of use refurbishments.

 

[ree]

I meant to say that rendering the patch might merely cause the moisture to move sideways or up or down.

 

[unknownfellow]

Hiya. If it is indeed salts rather than a continued source of damp then that could account for damp appearing when it's colder and wetter. Alot of the time salts are hygroscopic, which means they draw moisture from the air. The non contaminated areas won't, meaning a damp patch in the contaminated area on colder/wetter days.

If it's a very specific place though and there is a bathroom on the other side, are you sure it's not something like a pipe leak? Or maybe a breakdown of tile grout near a shower?

If it is the salt contamination and you can't treat the source of the damp then you can use a salt/damp-proof salt barrier cream & adhesive ( to effectively 'dry line' the wall with plasterboard and finish from there, as per normal. As long as the plaster board isn't in contact with teh wall it'll be fine.

There's also the traditional sand/cement render with salt resistant additive solution as well, requires a fair bit more effort though.

Here's some links to the materials:
http://www.amazon.co.uk/Dryshield-C...UTF8&qid=1401459035&sr=8-1&keywords=dryshield

http://www.amazon.co.uk/Drygrip-Adh...e=UTF8&qid=1401459171&sr=8-2&keywords=drygrip