And the construction costs of the additional area,...?
Moreover, the building envelopes do not get larger, so the exterior dimensions may even be placed over setback areas.
But none of us know the agreements either. In that respect, crystal ball, but generally I would be cautious at first.
To what extent do the thicknesses of the stones used indicate the sawing effort?
Not at all from the stones, but calculate it yourself:
17.5 cm KS stone, 20 cm insulation, 2 cm air layer, 11.5 cm facing stone.
The structural masonry leaf is 22 cm behind the facing masonry leaf here. That is not an entire joint course. So either the facing masonry leaf is positioned correctly, then the structural masonry leaf is out of alignment. Or the structural masonry leaf is aligned properly, then there is hardly any way around a random bond for the facing masonry leaf.
Apart from that, you regularly overestimate this. Drop the mantra. Sawing is totally normal and not a big effort.
Here with KS it’s okay, especially with aerated clay blocks it’s a dreadful mess. Take a close look at the shell construction photos here everywhere: millions of botched spots prove me right.
The structural masonry shell is 22 cm behind the facing masonry shell here. That is not a full joint spacing.
The joint spacing is 12.5 cm? Then that is practically impossible with facing brickwork. 12.5 cm is definitely not enough for insulation and an air gap. And 25 cm is quite a lot — even 22 cm is already above average. Usually, insulation is more like 16 cm.