Is the floor still too wet or is it already normal?

Hi, in our new build made of Ytong, the interior plaster was completed on 10.10.17.

On 23.10. the cement screed was installed with an additive of fast dryer. According to the screed installer, it can be covered after 14 days.

Now it is the end of January and in some rooms on the upper floor in certain spots it is still wet.

After Christmas, we placed a construction dryer for 10 days, which pulled about 1-1.5 liters per hour.

We ventilated regularly.

The heating program for the screed never ran properly, now it finally runs through.

It was thought that the walls are dry, but when the underfloor heating was reheated above 35 degrees, the same spots were wet again the next day.

One spot/corner also sounds hollow when knocking towards the dry area.

Is this still normal in those spots due to the enormous heat or do we have a moisture problem?

Our useless site manager says it is normal.

The very bad spots were before the construction dryer

That stuff in the corners dries really slowly. Especially since airing hardly removes any moisture with this [emoji299]️. Take sandpaper and lightly sand the corners. That removes the sinter, and the water can dry better. It really helps with gypsum plaster. With screed, you just have to heat and wait. And ventilate. Karsten

sandpaper = sandpaper?

The walls have already all been sanded, since the painters are already inside.
But they were also surprised and don't know anything like that.
They usually work for a prefabricated house company (timber frame)... but they also have plaster, right?

But nothing can mold if plaster for Q3 is applied on top now, right?

3 months and not dry, for me rather not normal. We had cleaning done on December 20th and in February everything was dry. However, we ran a dehumidifier for over 6 weeks. If the dehumidifier draws 1-1.5 L/h, the air must have been quite humid. What temperatures and humidity levels have you had in the house over the past few weeks? I would immediately complain about hollow sounding spots.

Hello,
Turn on the component dryer and the fans to circulate the air...
Best regards

So in the last weeks after New Year, the humidity according to our thermometer was about 55% on average. When everything is closed and the underfloor heating heats again above 35°C, it then sometimes rises above 70%. However, the painters are already in now. Regarding the hollow sound, what could that be? I was in the attic directly above and did not notice anything.