Damp plaster and stains

[Howie5]

Hi. First post on here as I getting a bit desperate now and hoping someone can give me some advice. Apologies for the big back story. 6 months ago noticed that my skirting boards appeared to be rotting in the living room and on closer inspection realised that the plaster behind was wet and in some places almost liquid. Wooden floor was pulled up and the plywood underneath was completely rotten so took the floor back to the concrete underneath and left it all to dry. The advice we got from numerous damp specialists and plasterers was that the damp was coming from the floor as it seems a damp proof membrane wasn't put down under the concrete floor. Someone came in and took the walls back to the brick, injected dpm, replastered and skimmed the walls and put some form of damp proof compound on the floor and self levelling too. 3 months later and the lower part of the plaster was much darker, either a salt like red our and some discolouring, was cold to the touch but didn't seem wet. Plastered returned and told us that was just the way it had dried, it wasn't damp and to mist coat it. 2 Mist coats applied and now the patches are still showing through including some yellow staining. I'm convinced we still have a problem but plastered keeps saying it's fine and OK to paint and the damp problem is solved. House was originally renovated 3 years ago and the original raised wood floor was lowered so that the floor level is below the next door neighbours and the other rooms in the house so there should be a void all round internally at floor level on the other side of the wall. All the issues are mainly with the internal walls. First photos show 3 months after plastering, second photos show a day after painting with mist coats. Any ideas?? Thanks

 

[Taptom]

Have a look at Peter Ward/Heritage House on YouTube - an education in damp, causes of, and con artists.

 

[Howie5]

Thank you, that has really opened my eyes. Might even fork out on a consultation with him as I'm desperate now, seems to know his stuff. Cheers

 

[builder1953]

The wall plaster should not be touching the concrete floor, this will allow "wicking" of moisture from the concrete floor to the wall plaster, there should be a minimum gap of 25mm between wall plaster and floor. It looks like gypsum products have been used to re-plaster, if so this is wrong unless they attached a wall membrane to brickwork prior to re-plastering, waterproofed sand/cement or sand/lime or renovation plasters should have been applied as the float coat before skimming.