How much adhesive is acceptable under floor tiles?

[oly]

I've managed to get floor pretty level using a few bags of self-levelling compound. I'm left with needing to put down over most of area about 8mm of flexible adhesive with 9mm thick porcelain tiles on top. This brings me up to the required level (threshold of sliding doors).

Is 8mm a lot to be putting down on the floor, or is it about right?

 

[Crystalclear]

6mm to 12 mm.

8 mm is good, but then if your were to do two coats say? And let the first completely dry? As long as you leave a key for the second one to lock into, it should be all good.