Screed drying - Incorrect drying program set

Thank you very much for your explanations! I find them very interesting and they have helped me as well.

I also thank you for this information! I have a question as well: Currently, we have the interior plaster inside, where I remove shock ventilation and moisture condensation on windows and reveals about 3 times a day (window vacuum cleaner, cloth). This was applied on 04/11/2020, so about 3 weeks ago. On Monday, the screed will be laid (cement screed). The underfloor heating has already been installed. Since there is no heating yet (heat pump) and the site manager says that it cannot handle the "rapid heating" anyway, an external device will be used (??). 1: What ventilation behavior do you recommend? 2: Shouldn't the underfloor heating "participate" to increase effectiveness? Or I have read the term "functional heating" in this context – what does that mean?

What I understood:

[*]Screed is not just screed and has individual drying behavior
[*]therefore it is necessary to measure the residual moisture at several points before floor covering
[*]Screed does not need underfloor heating to dry
[*]Fast drying is a desire of the builders and not a technical necessity

Then why not simply plan for 3 more weeks if you want to live in the house for decades afterwards?

To the OP: Better adjust your plans now than take a quality risk.

@ "bauenmk20":
This came in on 11.04.2020, so about 3 weeks ago.
"Since there is no heating yet (heat pump) and the construction manager says that it cannot manage the 'high heating' anyway, an external device is used (??)."
Answer:
Ultimately, a heat pump should perform a function. So it will enable the "high heating," the question is what temperature the construction manager expects.
The original questioner on this topic, "Tx-25," had already given the answer to your question with the note:
"It is an electrically powered external device."

Question:
"What ventilation behavior do you recommend?"
Answer:
First of all, the new cement screed must not be exposed to any draft. Even if most homeowners’ eyes will water: let the condensation on the windows drip down within the first 7 days, if it happens. Do not tilt doors/windows open, but let the cement have the water for setting until the end!!
After 7 days, ventilate frequently with shock ventilation. This requires multiple visits to the new home, where the windows upstairs and downstairs are thrown wide open for 10 minutes each and drafts occur. The water released will be discharged to the outside air, and the room air can re-humidify again after closing the windows.

Question:
"Shouldn't the underfloor heating 'contribute' to increase effectiveness? Or I have read the term 'functional heating' in this context – what does it mean?"
Answer:
The underfloor heating naturally helps to expel the mixing water faster from the screed structure through the thermal pressure applied. But it is not fundamentally necessary for the drying of screed!
We distinguish two types of heating a new heating screed:
a) functional heating and
b) readiness-for-cover heating.
The former is done stepwise up to reaching the maximum temperature to see if all components work properly and are tight. The gradual heating protects the virgin screed during its first encounter with the thermal stress via the heating elements.
The readiness-for-cover heating is seen as the continuation of the heating program after 1-2 days of rest (lowering the flow temperature to room temperature) and causes the residual moisture still present in the screed structure to be emitted via the screed surface to the room air.
Good ventilation is an important option here!
Regards: KlaRa

super thanks!

We still have 3x DN100 pipes running continuously on exterior walls for future exhaust fans. These are currently not sealed. Should I seal them before laying the screed? The site manager had no concerns when I asked him about this. The pipes are located 1x shower, 1x utility room, 1x bathroom.

@ "bauenmk2020": I’ll put it this way: We don’t want to overdo it, breathing in the room is still allowed. As far as drafts can arise through component openings, let’s call them that, this should be stopped before the screed installation. Screeds are not "mimics" in that respect! They just really don’t like drafts at all during the first 7 days. Regards: KlaRa