Crumbly Plaster beneath Bathroom Tiles ?

[peterjg1972]

Hi All

I have recently removed an area of tiling in my bathroom, around a window and sink area. The window is going to be reduced by bricking up the left hand side by about 15cm (double glazing is then being fitted)

In doing so, I have discovered the plaster beneath it was very crumbly and some of it came off with the tiles. I have removed the crumbly parts. The render beneath plaster also seems a little soft in areas too.
The original edge beading is also badly rusted.

From this situation, How should i best approach getting a good solid surface to tile onto.

Thanks for any advice

Pete

Untitled

• peterjg1972
• 23 May 2010
• 2

 

[benwilliamson]

it doesn't look that bad, i do bathrooms for a living just tile over it but obviously take any loose of and fill any big gaps with somthing like hard wall or pasterboard adhesive and always pva it or sbr bond it,

all plasters are pourous and the new tiles will fall off if you don't pva/sbr 5.1

 

[Richard C]

You’re going to have to re-plaster the reveal once the new window has been fitted; it’ll be fairly easy to rectify at that stage. I would advise you at least rough fill any holes to ensure you get the wall as flat as possible before re-tiling. Don’t use Bonding or Hardwall, it’s not suitable as a tiling surface, use a little finishing plaster or sand/cement render or even cement powder adhesive prior to tiling; what size weight tiles are you using?

Apply a little PVA where the holes are as it will bond the filler but DO NOT use standard PVA on any surface to be tiled, it’s not suitable. If you need to prime, only use SBR but always follow your tiles adhesive manufacturer’s instructions.

 

[joe-90]

The plasterer will have used PVA - but his skim doesn't fall off.

 

[Richard C]

PVA serves a totally different purose when used as a plastering aid as you well know joe & you skim when tacky; if you skim over dry PVA then your plaster will fall off - probably