It went so far that he says, if there are cigarette butts left on the property afterwards, he will charge that as disposal of trash by external trades.
Are they all crazy by now??? Here, the construction crew came every Saturday and solely to clean up. Voluntarily! We were surprised because we had prepared ourselves to clean up the construction site on Saturdays if no one was there. But they were earlier
...you would have to initiate evidence collection because of something like that.
But one could also install a webcam surveillance, there is a specialized company from Düsseldorf specifically for large construction sites
Aside from the fact that this contractor has already disqualified himself several times here... I would not engage in any further discussions and just clean up myself, and if the site gets too dirty, simply check more often. The more promptly you are there, the easier it is to narrow down the circle of those responsible.
Normally, if the general contractor hasn’t hired the last berserkers of the republic, the craftsmen are tidy by themselves and also reasonable if you talk to them. There hasn’t been any stress so far. Conversely, I would increase the offer of garbage bags and give them as many opportunities as possible to properly dispose of the stuff right away. Apart from that, personal contact combined with coffee and rolls or pastries as well as the constant supply of water and cola for free use also helps.