Screed Heating Phase - Air Humidity

According to the site manager, I should ventilate each room at least once daily. Use a hygrometer to check the humidity. It should be at 40%. Now, I have been ventilating every time for the past 3 days (heating has been on for 3 days) and I don't really achieve 40%. I spend about 3/4/5 hours in the house each time to carefully ventilate and make sure the humidity goes down. There are 1-2 rooms where I can get below 50%. In other rooms it stays around 60%, in the guest WC and storage room/HAR (basically one room with a passage) rather 70%. Before ventilating it is usually around 90%.

Is this normal? Am I doing something wrong? What do I need to do differently?

The storage room/HAR has 2 windows on the same wall, basically each room has one. (the rooms are only separated by an open passage) Can I open both windows at the same time here to get more air movement? For the hallway, where there is only the front door, would that mean also opening the front door or really only referring to the rooms?

Thank you!

Morning. Don’t look at the numbers. Start at the bottom and open all the windows, then go upstairs. The only thing you should observe now is the window panes. If they are no longer fogged up - close the windows. Done. And you do this as often as possible. If it unexpectedly gets cold again, ventilate shorter but more often. You want to get rid of the moisture, not the heat.

If you only open one window, how is the air supposed to get out and consequently the humidity decrease? Strange tip with room by room. Open all windows for 5 minutes, then you'll have under 40% (provided it's not too cold in the house), do this 2-3 times a day, whenever you have time.

...and why should it be 40% humidity??? Do you have a timber frame prefab house? Especially towards the end you won't even reach 60%, then it's like a sauna upstairs. How is anyone supposed to achieve those values in summer? There is no standard procedure for that, except airing out crosswise several times a day, so don't make a science out of it.

So currently there are no windows fogged up. If at all, then very, very little in the guest bathroom. That’s it though. What is damp is the insulation around the pipes. Like an insulating sleeve.

Please forget such numbers. In a newly built house it is only temporarily possible to get the RH below 40% because there is too much residual moisture in the building. This will remain so for about 1 year. It is helpful, regardless of the season, to air out 2-3 times a day by fully opening the windows (and only that), wipe the frames, every drop counts. The combination of warmth and ventilation is the key.