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Plastering & Rendering

PVA on cement internal (external) wall before plastering?

Anonymous user 09/03/2024 - 2.38 PM

I just knocked off the old plaster (approx 20mm) from and internal (external) wall as it was loose and sounded hollow. At this point I was left with the bricks, and I re-levelled the wall with cement and sand coat, and scratched it to give the plaster the key. The question is now, shall I apply PVA to this wall before plastering or not? I'm worried that being an external wall it needs to breath, and PVA would seal it instead creating mold??? Thanks for your comments

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3 Answers

MasterKraft

Rating: 5 out of 5
Cullompton
Any wall that can absorb moisture, barring plasterboards in general, will need to be glued.. (a term used by pasterers for PVA). This mops up any loose dust and aides adhesion of your first hardwall layer of plaster. It also prevents the new plaster from drying out too quickly as the old surface would tend to suck the moisture out of it - this would lead to cracking of your new plaster as well. Concerns about mold would only be aggravated should there be rising damp/ineffective damp course sealing, or water penerating from ouside under poor finishes, sealing. Good luck... :)
Answered9 April 2016
2

Anonymous user

Hi you will need to pva the wall first before applying any plaster as you should before you plaster any wall hope this helps. Prestige decorators and builders
Answered9 April 2016
1

Anonymous user

The wall has already been sealed by putting cement on to it tanking is the worst thing to do if you want the wall to breath and no build up of moisture causing the damp then lime plastering is the way to go I come across loads of jobs that have had tanking done on the buildings all it does is hide the problem for a few years then the damp comes out above the tanking so the problem was nether solved just a quick fix
Answered11 April 2016
1