Cool answer. Why didn't you just ask your acquaintance right away, then you wouldn't have "stolen" life time from some people here and yourself for the clarification.
The average builder would probably spend somewhere between €20,000-25,000 on windows and you want to discuss a travel cost?
You can of course write it off as unforeseen expenses. But repeatedly, and until the construction site is finished, a nice sum will come together, which the OP surely knows better how to invest.
I do not book that anywhere, the service provider is allowed to do that. With that volume, he can dare to issue an invoice for an allegedly additional trip. If the work environment is clear, then he has to organize at his own expense.
At that volume, he can dare to charge for a supposedly additional trip.
Whether you make two consecutive days of trips in a row or two non-consecutive days, it does not change the cost of the trip. That's what I say as a former window manufacturer.
