Plastering a wall back to brick?

by Steve
(Norwich UK)

Hi,

I'm doing up my bathroom and the plaster has come off the wall, it's about 20mm thick, say 50% of the plaster is left on the wall seems well stuck the other 50% has gone back to the brick.

My question is what is the best thing to put on the wall first to bring her back to 20mm and then even out flat.

Or do I need to take all the 20mm off and go right back to the brick.

Regards

Thx

Steve

Answer

Hi Steve

You need to put a backing coat on to bring it out level to the existing - no need to take off what has already stuck. A sand & cement backing coat, or Hardwall or Bonding coat can be used for this.

Sand & cement mixed up 5 parts sand to 1 of cement with a bit of plasticiser
or
'Hardwall' (sets within 2 hours)
or Bonding coat (also sets within 2 hours).

If the wall is at all damp or you are going to struggle to complete in a few hours then sand & cement is the best to use. However using Hardwall or Bonding Coat does mean that you can complete the skimming the same day.
Whichever type of plaster make sure you use a straight edge that will reach though to the existing plaster to ensure everything is flat.

You can then pva the existing plaster and apply a skim coat to the whole wall.

Hope this helps

Paul