new plaster comes away ...

[teddyb]

Hi
Our house has lime plaster inside (we're told) and have recently had some walls skimmed for new decoration. While removing some nibs, a large 'flake' of newly skimmed plaster has come away. We are going to contact the builder, but can anyone suggest why this could have hapened? Always grateful for you comments ...

 

[roy c]

Maybe they skimmed over painted or smooth walls without "keying" the new skim to the wall...If skimming over existing walls (be it old paint or old plastered walls) the walls must be sealed and sometimes "keyed" to allow the new skim-coat/s to adhere to the existing surface. There are a few ways of doing this which involves different types of "bonding agents". I usually apply PVA to the surface that is going to be skimmed then leave it over night then before I skim it I roller on another coat of pva and skim when it "picks up". Sometimes on shiny painted walls I will mix some sand in with the pva on the first coat to get a "key" or even scratch the wall with a stanley. Never had a problem after using these methods. Like I said there are other "bonding agents" but I have always used pva, and also sbr for different circumstances.....

 

[roughcaster]

Just to add to what roy c said, if one area of plaster skim has blown, then chances are there will be other areas ready to go the same way. Rub over the wall with the back of your hand, letting just your fingernails touch the wall and you will hear any loose or hollow areas. Find out the extent of the problem before you get the builder back.

Roughcaster.

 

[teddyb]

Thanks for your help. Is there any difference to skimming over lime plaster and any other sort?