ᐅ Is a bonding slurry necessary for terraces with natural stone ceramic tiles?

Hello everyone!

Since this is my first post here, I hope this is the right place to ask 😉

We are currently renewing our terrace and using natural stone porcelain tiles from Emperor with a thickness of 2 cm (0.8 inches). We have a paver helping us with the work.

We have removed the old soil and compacted the ground (sand / gravel). On Saturday, about 10 cm (4 inches) of drainage concrete will be poured, and the tiles will be laid directly on top of that. The terrace is bordered on all sides either by the house edge or lawn edging stones, so it is not free-standing.

Now to my question:

My paver says we can lay the tiles loosely onto the fresh drainage concrete, that it will adhere well, and that the tiles will not “move” afterwards. However, I’ve read online that a bonding slurry is supposed to be applied under the tiles. Is that really necessary, or what disadvantages would I have if, as my paver plans, this step is skipped? The terrace will not be driven on, only used for sitting and relaxing, so it won’t bear much load.

Best regards

Schmuff