ᐅ Elevation and floor structure. Was this done correctly?

Hello,
we are currently having the floor structure installed. The total planned thickness is 16cm (6.3 inches), divided as follows:
5cm (2 inches) expanded polystyrene insulation
3cm (1.2 inches) mat for underfloor heating (to be stapled)
6cm (2.4 inches) screed
2cm (0.8 inches) floor covering (tiles)

The 5cm and 3cm layers are already laid. Next, the pipes need to be installed. When we were at the house today and measured from the height reference point to the top edge of the underfloor heating mat, the values ranged between 106cm and 107cm (approximately 42 to 42.1 inches). This suggests to me that we are missing about 1 to 2cm (0.4 to 0.8 inches).

We do not believe the height reference was applied incorrectly, as it was set during masonry work and after plastering the walls, with the markings being almost identical. The correct thicknesses of the layers (5 and 3cm) were also used. We are unsure whether we are worrying unnecessarily or if something is actually wrong.

We also noticed that when walking on the mat, it compresses slightly — meaning it can be pressed down easily.

Could it be that the mats will be further compressed by the weight of the screed?

If the underfloor heating pipes are embedded in the screed, adding them up brings me to the 16cm (6.3 inches) you mentioned. Where do you see the problem? Is your cross-section for the underfloor heating pipes plus 6cm (2.4 inches) screed height, or does it include it?

According to the height section, it seems there are only 6 to 7 cm (about 2.5 inches) left, although we still need 8 cm (about 3 inches) for the screed and tiles. The 6 cm (about 2.5 inches) consist of the diameter of the heating pipes and the 4.5 cm (about 1.75 inches) minimum coverage of the pipes. The problem I see is that, for example, the front door might no longer be able to open. Therefore, I wanted to know if the installed panels will be slightly compressed by the weight of the screed or if we already have a problem now. When the height section was installed, we checked several spots. The line was 16 cm (about 6.3 inches) above the raw concrete slab, but now 1 to 2 cm (about 0.4 to 0.8 inches) seem to be missing, even though the planned thicknesses of the mats were installed.

I understand now.
Hmm, I’m not sure about that either, I didn’t measure anything like that back then. I would ask the site manager or the screed installer.

Unfortunately, you always just refer to "boards" in general.
Thermal insulation boards will not compress because their structure is rigid and firm.
For impact sound insulation boards, the typical compression is at most about 2-3mm (less than 1/8 inch) per layer (from a practical point of view).
Best regards, KlaRa