Very Smooth Cement Substrate - Tile Advice

[Dajoca]

Hi. I'm tiling the four walls in my bathroom.

It was previously tiled half way up and where I removed those, the old plaster(?) underneath was like soft pumice, so I hacked it off and re plastered, primed with SBR and tiled the lower half of the room using Mapei cement based adhesive.

The top half of the room is a good condition and very smooth cement finish.
I've scored the surface slightly, but can't imagine that the cement based addy is going to grip at all.

Do I need to key this surface and is there an adhesive that will provide good grip on to a very smooth cement surface?

Cheers

 

[Dave]

If it won't rough up , then you could slurry coat for adhesion... Ive come across a few walls like that , most were prefab walls/houses and like you say quite smooth shiny substrates.

 

[Dajoca]

Thanks for the reply Dave.

I had a tub of Evo stick superior strength to hand, so I did a test on some waste tile.
A dab of adhesive, pressed on to a smooth area and left overnight.
The result was a very firmly stuck tile and applying enough force to remove it, tore a hole in the substrate.
So even though I have a patch to repair, I don't have to worry about poor adhesion.

Cheers.