Screed no functional heating after 7 weeks

Interesting. We received cement screed with fast binder and with us only the first days of drafts were forbidden. After that, all windows were left on tilt. Three weeks later, the heating protocol then began. Could that have been due to the fast binder? The screed now looks perfect after the drying phase.

Is it really a property developer, then it's surprising that you are allowed into the house.
If not, building a house also requires some personal responsibility. After at the latest one week, you should have at least thoroughly aired out in the mornings and evenings by shock ventilation.
You should have a window handle.

Yes, it is a property developer – to possibly ventilate ourselves, we would need the permission of the property developer. If it is allowed, we would gladly take over, then we know that it is done. The window handles have been removed.

Our windows also didn’t have handles at first, obviously so they wouldn’t be installed. There is exactly one insert handle for that purpose, with which you can then open all the windows. After 2 days, we had one window downstairs and one under the roof tilted – and that worked wonderfully. However, it was also 2018 and a hot summer for us. The underfloor heating was only heated up hm 4 weeks later. So step on your person in charge’s toes, have them give you a handle or, if necessary, buy one yourself at the hardware store and then get the moisture out, otherwise it won’t work.

That is not their house! She is not allowed to do that. That is someone else’s property. It only becomes hers upon purchase. She can only say that if they build it so sloppily, she won’t buy it.

Well, that’s then unfortunate. And once again, I know why we forgave ourselves.

Well, that's unfortunate. And once again, I know why we awarded the contracts ourselves.

This has nothing to do with awarding the contracts ourselves, but with the difference between property developer — general contractor, main contractor, individual awarding. Even without individual awarding, with a general contractor you are allowed to enter the house and open windows. Or am I misunderstanding "awarded the contracts ourselves"?