From when do construction helpers become illegal workers?

I have just filled out the forms that you receive after registering the construction project. In doing so, I came to the interpretation that most helpers are actually not insured. Close relatives are not insured anyway, and all others only if their help goes beyond the "usual" extent. So if someone works for half a day, it is a favor and not insured. If, for example, they take extra vacation and work hard the whole week, then they are insured. At least that’s how I understood the case examples. I had to tick which trades are EL and which are done by a (to be named company). I am curious what will come my way.

6 months usual construction time are 120 working days. 4 people working simultaneously on the construction are 480 PD or 3840 working hours. Then the hut is finished. Where did you guess 10,000 hours from?

6 months is very unrealistic. Doing it yourself you’ll rather take 2 years. With companies 8 months...