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Unbonded plaster - expert help please

Postby milly » Sat Mar 15, 2008 11:11 am

Urgent help please! The original plaster (28 years old) in my lounge showed many filled-in holes and some small cracks so the plasterer reskimmed the walls with Knauf finishing plaster. The finish was not good so he covered the rough areas with Gypsum easifill. As the plaster dried, it became obvious that it was not bonded. The plasterer said this was because his assistant had not pva'd the walls. He said he would have to take off the new plaster and re-skim but he now tells me that if he puts on a topcoat of pva, the pva will soak through and bond all layers to the render. I did query this with him but he insisted it would rectify the problem. He would only reskim any areas which fell off.
Since first posting this, my plasterer (now ex!) has pva'd all the walls. He has filled the areas, using both Knauf and easifill, where the plaster fell off on touch. This new plaster has blown, the first Knauf he applied still feels loose, and the whole room looks a horrible mess!!!

If you are a skilled plasterer, please, please tell me what now has to be done.
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Postby gary burton » Mon Mar 17, 2008 8:53 pm

Hi Milly,

Unfortunately - your guy does not really know what he was doing and sadly - has learned his mistake at your expense.

I am not a plasterer - but a professional builder with my own team, but those of us who work in the trade professionally know that he should have sealed / bonded the wall initially.

What has happened is that the old plaster has absorbed the moisture from the new plaster mix, leaving the new plaster without enough adhesion to stick. Putting PVA and plastering over the problem simply will not work.

I am afraid to say - the only way now to rectify the problem properly is to strip off the plaster (even back to joists or brick if necessary), dry - line where possible, and start again so you will have a nice job done.

If you are confident enough you can strip it off yourself to save money - but do go gently as there may be buried pipes or cables in the walls.

Sorry to be the bearer of worse news, but often this is the only way forward when someone has done a botch job.

Good luck

gary burton
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