Prepare a hearth before tiling.

[DaveyBoy76]

We have this fireplace which I want to tile.

The hearth is alright, but could do with some patching/repair/flattening before I start.

The old tiles became detached from the hearth before we bought the house, so looking to make sure that that doesn't happen again.

What should I use to prepare this area for tiling?

Thanks.

 

[tomm12]

It depends on what kind of prep, and how deep, is under what we can see but if everything is OK then prime the surface shown in the pic, and then use a skin of SLC to even it out.
But if the whole hearth is loose and just hanging together then dig a bit and clear everything out.
Then build up in sand and cement or concrete and start from a more solid background.