Why don't construction prices go down?

That is exactly my remote assumption, the wall was built without sawing

If so, it would clearly be a cracking caused entirely by the masons beyond any tolerance. There is NO reason not to saw if the factory plan requires sawing. Otherwise, a service would be billed that was not performed.

And as I said, I do not want to judge whether it is wise to have a factory plan with sawing during masonry. I believe like you: it is not.

Because of the discussion with above: Were stones cut in this 3.98 wall or not?

Every row was cut - I have enough photos of it...

Then the limiting wall was placed incorrectly or what? Otherwise, it doesn't make any sense...

You describe the theory, I say how it will work in practice. Nobody will redraw the wall for you. And if you don’t pay the down payment according to the contract, the general contractor will not continue building. I would never have thought of planning the kitchen according to shell construction dimensions in 100 years and my kitchen installer told me exactly the same: "When the plaster is on, I'll come and we measure. Afterwards(!) we plan in detail." Of course, sockets have to be roughly positioned beforehand, but not down to the millimeter. Windows etc. are different because then the general contractor has the problem himself. He will put his bricklayer on alert if he has to reorder the windows. Mistakes can always happen. Probably someone cut the first layer wrong, reading errors, took the wrong section, something like that... and then things just kept getting added on.

No one is demanding that either, that would be disproportionate. The question is whether there is a defect and whether is entitled to damages. In my opinion, it is. But yes, if he brings this up now, the general contractor will stop the construction, which is why my suggestion is to deduct it from the final payment first...

However, the compensation will not be as high as one might think now. I estimate 100 EUR? Ultimately, a cabinet must be changed from 90 to 80 or from 60 to 50. That's all there is to it.