Hi all, wonder if you could give me some advice. I have recently had a gable end re-rendered and internally the plaster has been knocked back to the brickwork. The wall has been professionally replastered using a cementitious base (renovating plaster or dry coat) and then skimmed with finishing plaster. The problem is that nothing and I mean NOTHING is sticking to the dry plaster. I have tried mist coats - it peels off. I have sanded the wall back and re applied trade matt - it peeled off. I have today applied specialist primer which has peeled off in places. The wall is not allowing the emulsion to soak into the top coat plaster. I would wallpaper but I don't think the adhesive will stick! Any ideas gratefully received as I am pulling my hair out and there is not much of it left anyway! cheers Jools
Sounds like someone used tons of pva in the plaster mix. Nuisance I know, but try a test patch with an oil-based undercoat. Mr. HandyAndy - Really
Cheers Handy, There is something def in the mix but the plasterer says no (yeah I know lol). Will get some oil based primer and see what happens and advise! Once again, many thanks for the reply, really appreciated... Jools
Has your plasterer over polished the plaster i.e. does it have a glass like finish. If he has then more than likely nothing will stick especially if the wall is not fully dried out. If it's over polished then any wall coating will just sit on the surface and not bond to the wall.
Hi Dunk, no, the wall was left with a non polished finish. Been there and done that lol. I have used some Zinsser BIN shellac primer today and fingers crossed it seems to have worked. Only tomorrow will tell. Thanks for your advice. Jools
Let us know how you get on, curious as the only other thing I can think of apart from a damp problem would be something added to the mix. Just re-read your initial post so have a couple of questions. 1. Was the wall re-rendered and re-plastered due to a damp problem? 2. When you said you used a trade Matt paint on the wall was it vinyl Matt or contract matt (non-vinyl) as you can get trade Matt in both vinyl and non-vinyl forms.
The wall was re-rendered because the original render had failed and had not been rectified so several years of historical weathering. Gable end is facing prevailing weather. Definately internal stonework was wet but we have used dry wall and renovating plaster in the past to control the moisture. There has been efflurescence. We used a professional plasterer and renderer.Not had a problem with this on previous renovations unless of course there was a strange mix with the raw product? As far as I am aware no additives like PVS/SBR added to finish skim. I have used a damp meter and readings are at 1.5% but this is the same as walls we know to be moisture free. Yes it was contract matt which I tried as mist coat 60:40 water/paint but that did not soak in and just peeled off. the Zinnser BIN primer I used was expensive, stank to high heaven and was very watery BUT it went on a treat and seemed to do the trick. Fingers crossed for tomorrow. May be back crying tomorrow lol.
Right the efflorescence is the problem here as you have had a damp issue, the salts are rising to the surface of the plasterwork as the wall is drying out. As the moisture evaporates it leaves behind the salts as salt does not evaporate with the moisture. All you can do is keep brushing off the salt until it stops salting, this can take anywhere from a couple of weeks to 6 months. Any coating you apply will peel until the wall has stopped salting. Salt will also attract moisture from its surroundings ie the humidity within the room. Once the salting has ceased your paint will stick to the wall. Hope this helps.
Newsflash: The primer and the paint stayed on and it looks great! Thanks Dunk, really helpful and I really appreciate yours and Handyandy's replies. Cant recommend that Zinsser BIN highly enough! Jools
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