Floor structure for ventilation system on the upper floor

The [Kontrollierte-Wohnraumlüftung] manufacturer...

With us, the pipes lie directly on the concrete, and insulation was placed between and on top of them, followed by the underfloor heating.

With us, the pipes lie directly on the concrete and insulation was placed between and on them, then the underfloor heating.

Thanks for the pictures! Do you have a (heated) basement? How many cm thick is the insulation layer on the ground floor? What did the floor construction look like on the upper floor?

Yes, we have a heated basement.
Upstairs looks the same, but I don’t have a picture like this. I only have this one now.
I would have to measure the height at the stairs.

So the pipes are directly on the ceiling, i.e. on the solid wood without insulation underneath and only with insulation/filling on top?

Yes. The filling encloses the pipes precisely. The filling and screed are floating.

Hello forum,

the required minimum thickness of the screed is regulated in

DIN 18560, Part 2, "Screeds and heated screeds on insulation layers."

For an expected load in residential rooms of 2.00 kN/m², table 1 requires the following values for cement screeds:

Minimum thickness >45 mm
Minimum flexural tensile strength F4

Therefore, the original floor construction with 65 mm is completely sufficient.

When properly executed, experience shows that there are no problems with the chosen construction.

In this context, the installation of the thermal insulation and the ventilation pipes should be carried out as carefully as possible to ensure load transfer. Attention should be paid to laying with as few cavities as possible.

Best regards

Kristof