Change after building permit

with the amendment, a new site plan must be submitted. The surveyor does it, costs you a small three-digit amount.

I'm surprised.
As long as everything is within the permitted area, a few pen lines drawn with a ruler on the existing site plan are sufficient as far as I know.
It wasn't a pen this time, but the drawing in the site plan was not done by the surveyor in our case, but by the architect. And the small changes within the tolerance were drawn in with a thin red felt-tip pen.

Yes, that's right, it naturally depends on the federal state and the conditions, e.g. development plan or not. No development plan and Saxony, it would have been required for the amendment application. With a development plan and NI or HE, a pen would do.

But for which "damage" is which "insurance" supposed to cover?

So if on Ash Wednesday I confuse a boundary point on the construction site and my coordinate system is twisted so that the true boundary distance of 3m narrows to 1.5m, the foundation slab is poured and the neighbor notices, it must be rebuilt. These costs are covered by my professional liability insurance. If the contractor does the same, he is liable for the damage. His liability assumes gross negligence due to lack of expertise, unless he is not only a master bricklayer or civil engineer, but also a survey technician or engineer.

Whether with or without surveying, all parties will blame each other for years

If I have prepared a staking plan, can present photos of the construction site with my measurement points and can also electronically document a correct staking, then the contractor screwed up; otherwise it’s my responsibility. Then there is nothing to shift.

The argument about liability only holds, in my opinion, as long as the case never occurs.

I have to contradict you from my own experience.

Thank you for the explanation. Everything is clear so far. I had assumed (I should have written it down) that a surveyor does not make mistakes and that both the plan and the precise staking on site are always correct. The risk rather lies in the execution, and there one will wriggle back and forth, and their insurance (if available) will find reasons not to pay despite the survey having been done. There are simply too many people involved. With friends, the battering ram frame was already damaged when the excavator was unloaded. Fortunately, the client insisted on calling the surveyor, the excavator driver "Category Pavel" was already trying to drive the crooked/splintered posts back in. In the end, it was no problem, but in such a situation, I can imagine it would be very difficult to hold a subcontractor’s subcontractor’s insurance accountable.