For concrete with hairline cracks apply aba ceramic tile underlay prior to tiling.
How to render a wall for tiling.
Tear down and remove old wallpapers.
If you decide to tile over the render do not pva it as all the tiles will fall off eventually see previous threads for reasons.
It must be clean dry and free from dust laitance or any other contaminants which may act as a release agent preventing the adhesive from bonding to the render.
Look out for signs of wall hangings such as screws nails or other types of fittings.
I have tiled over rendering before but it was a small area 3 sq.
Here are a few minor preparations before you tile a wall.
Get rid of loose plaster.
All concrete release agents and curing compounds must be removed by mechanical means.
Repeat the process inside the border and use the borders as a gauge to get all the walls correct.
Allow the mortar to set before applying the grout.
Apply the render all round and make sure they meet with the straight edge and levels.
Once your edges are set you are pretty much ready to go to fill in the enclosure.
Alternatively you can use barrierflex abaflex or isoflex.
For cracks larger than 1 5mm consult your local suppliers.
Add and press the grout until all joints are filled and remove the excess.
Preparation the render must be a minimum of 2 weeks old to enable movement caused by drying shrinkage to have taken place.
Sand the wall to level it down if required.
Look out for signs of damage and cracks.
Fill larger cracks via layering.
Cover both the brick and the tile with mortar before applying the tile to the wall.