Costs for the heating & sanitary trade

I think technically it’s doable, but it seems so unnecessarily inefficient to me. Then the argument is made with the windows that the dirt and dust from cutting the roof tile is so bad and the windows should only be installed after roofing, but when chasing plaster inside it doesn’t get dusty and dirty? And of course I’m supposed to clean up the dust and dirt (or rather my subcontractor) because it’s my trade.

I imagine it's stupid if the plumber then chips into the electrical cables.

Exactly! That too! Although - you can see where they come up from the floor...

Why do I do it this way, is there really no advantage? Or is it done this way in your general contractor so that the trades are clearly separable regarding warranty?

That is my assumption, I still think it's nonsense. The rough installation of the sanitary system is not that sensitive.