Surface prep work for large tiles Help

[stephen hardy]

Looking for some advice from the tiling pro's..

Fitting a large amount of natural stone and most of it is onto backer board or new plaster board, some jobs coming up are fresh plaster and painted walls.

The last time I had one tile come loose I had primed the walls with PVA watered down but it appeared to have pulled the PVA from the plaster??

and where there was paint it just pulls the paint from the plaster?

What do you's do? surely you don't have to strip all the paint off?

Is there better primers out there?

or just spend more time putting them on.

Cheers

Steve

 

[peckers]

Firstly make sure the stone tiles combined with the adhesive and grout is not to heavy for the substrate you are tiling on! it looks like you are tiling on several different substrates, The weakest one is the fresh plaster on plasterboard, This substrate can only hold 20kg per 1m2 including the adhesive and grout! the rule of thumb i go on for tiling on this substrate with stone is for the stone to be no thicker then 7mm, however some stone is heavier then others, so check the weight!
Do not use PVA this creates a barrier between the adhesive and substrate, this is what probably caused the tile to fail last time. You can use an acrylic sealer/primer or sbr.
Regards to paint I would take off all loose flaky paint with a scraper and then sand the rest off with a orbital sander, and make sure you have a good key to take the new tiles.
Hope this helps...

 

[doug boardley]

I agree with all peckers has said in above post, only thing I can add is to use a single part flexible adhesive (powder) and not a tubbed ready ixed dispersion adhesive

 

[stephen hardy]

cheers lads

the only problem these days everbody wants travertine and limestone bathrooms so you must be looking at 27kg per m2?

I will try the acrylic primer next time, the last one I done somebody had used semi matt emulsion paint so I had to steam if al off.

If you go to a job and the client wants 12mm thick travertine or natural stone what do you do? over board with backer boards for the weight?

I think 12mm plaster board has a weight of 25kg ish??

cheers

steve

 

[DHTiling]

12mm plaster board holds 32kg of weight....backer boards is 45kg and over...