Construction of screed garage floor with point electric underfloor heating

As described in the initial post, there will be no slope for proper drainage.
There is simply too little water here, and to be honest, I do not want to go up to 13 cm buildup.
As I will do it here now, I would proceed as follows:

Have screed laid on an untreated and unsealed base slab. (Are there edge insulation strips with composite screed, actually?) 25mm at the front, 50mm at the back ending at 6 meters. The remaining 3 meters at the back remain level at 50mm. (Shelf area and workshop area)

After an appropriate waiting period, grind, prime, and treat with resin. Finally, apply concrete paint and done.

Buy rubberized mat and infrared heating and enjoy tinkering even in winter.

So, after consulting with the screed installer, I have the following statement: Composite screed is rather out of the question because the floor slab would still need to be shot-blasted. For this relatively small area, it is simply uneconomical to find someone who does that. That means a screed with a separation layer would have to be laid. However, this would need to have a minimum thickness of 50mm in the driveway area and from the rear area then 80mm (due to the slight slope). Is that understandable? It’s actually not the answer I was hoping for ops:

Hello "Patkia". Shortly before I go on vacation, a final note regarding the feedback from the screed layer: The shot blasting procedure actually requires a corresponding surface area. As a screed layer, he should know the alternative option, which is also common in practice, that the floor slab to be prepared is either ground or brushed with a steel brush attachment and a single-disc machine!! Please do not let anyone feed you false information about the only possible procedure. I admit that he will earn more on a thicker screed than on a 25mm thick bonded screed, but that should not be decisive here. His note about 50mm is clearly wrong, as the screed (now executed as a separating layer screed) cannot bear the expected traffic load. It is undersized at 50mm. The minimum thickness for a bending tensile strength of F4 with a surface load of 5kN/m² (which corresponds to a heavier limousine) would be >= 70mm, for F5 >= 60mm. And that at the lowest point!!! If the screed is also to be designed as a slope screed, then it does not fit at all anymore. With an additional 30mm to 40mm, optimal compaction of the lower screed structure is no longer possible on the one hand, on the other hand, a screed (except a bonded screed) must be executed in as uniform a thickness as possible. Otherwise, it will crack all over, and that will be a joy. And unfortunately, this is no joke!! Please specify a bonded screed to him after appropriate mechanical preparation and tell him that the project or his performance would be monitored in the background by an öbv expert of the screed trade.... Good luck, I am signing off! Regards: KlaRa