Efferesence on plaster??

[workhorse]

Hi all
Just moved in to a renovated cottage,(200 years old) it has been treated for damp and wood worm about 18 months ago with a 30 year guarantee, however we have a small area in the hall where the paint has bubbled up and is easy to scrape off. Called the damp man in who did the job he says " Its just the salt in the cement or plaster coming to the surface, use white vinegar to draw out the remaining salt and then paint over ok"
Is this for real or is he trying to avoid coming back and redoing taking off the plaster and sealing the damp course

any help appreciated
Thanks

 

[noseall]

it is common for damp masonry to bleed efflorescent salts as part of the drying process.

soil retaining walls for instance will carry on this process for years whereby the wall is continually in contact with the soil. the wetting and drying never stops.

if however the wall continues to produce efflorescent blooms for prolonged periods of time, then be worried.

i'm not so sure about the vinegar thing though.

 

[noseall]

p.s. there is no damp proof 'specialist' out there that has ever convinced me that what he is doing is any good whatsoever.

 

[timmyquick]

Well as far as I'm concerned money has been wasted, i have had damp professionals out twice. first time solid 9 inch injected with fluid. The damp came back with salts ruining plaster. Second time different company injected with cream failed again.

Neither of these 2 companys who did work will honour there warrantys so forget it.

solution, fix your self useing a damp proof membrane as it allows airflow to remove damp & moisture into the atmosphere. This has now been installed by my self for many years and damp is a thing of the past for me! and I'm getting a dam good hand at plastering because of it.

basically no chemical damp proof coarse will work 100%

http://www.restorationuk.com/shop/2/

 

[workhorse]

Hi

Cant install a membrane as the patch is in a hall within internal walls, the floor is tiled and no way will I be allowed to it dig up!
Is there any product that is capable of drawing these salts out assuming that this is what is happening, and not damp creeping in to the internal walls?

Thanks

 

[diyisfree]

If your property is a solid stone wall then simply trapping the damp in the stone with a cement render is not the answer.

Stone solid cavity walls need plastering with lime plaster, this allows the wall to breath and moisture to evaporate naturaly.

If you apply a cement render, you are simply trapping moisture in the wall. Eventualy the salts will seep through. Also the use of an acrylic micro porus paint will allow moisture to escape and prevent blistering.

This link may explain a little better

http://www.lectros.com/pdf/Antimould_Breathable_Replastering_Paint.pdf