Limestone threshold, groundwork?

[Berguven_glenn]

Hello,

I am planning to install a 20mm thick limestone threshold against the balcony (the house structure is brick laid with weak mortar, where the picture shows previously raw concrete that has now been removed).

I have just applied weak mortar to even out the roughest holes that were in the brick wall after the chiseling. I have been careful to make it as flat as possible with various trowels, scrapers, and rulers. It is of course not perfectly flat as if one would float or lay floor chipboard.

Now to the question:
Would you dare to lay a 20mm limestone slab directly in natural stone adhesive on this? I am afraid it won't fill adequately, it's a bit too uneven, and that the slab might crack (there is a fossil right across the slab (short measurement) which is a perfect breaking point...)

Thanks in advance

 

[jonaserik]

It is possible, but make sure the adhesive is combed with about 6 - 7 mm height and about the same width, the tile should then be laid on and rubbed down, during rubbing the adhesive will even out underneath and fill up as it should, essentially creating a completely underlying adhesive. The height of the finished underside tile will then be about 3 - 4 mm higher than the substrate + the tile thickness, you need to measure carefully.