Survey of saddle roof knee wall height

That is a very beautiful house. The short eaves also prevent it from looking too low with the 75cm.
I would probably now also build a somewhat taller house with a flat roof. But then the problem with the smaller attic remains; we have no basement.

We have neither a basement nor an attic in the house. Instead, we have a 55 sqm garage that has an attic and additionally a technical room and a utility room.
But a basement would sometimes be practical.

but on the other hand, don’t place the window sill too high

Sorry for asking stupidly :D, but what exactly do you mean by that?

In my opinion, that is a very practical measurement.

By the way, I agree with that. In our building application/permit, despite the 1.30 m, two full floors are designated. We built in Hesse. We can actually stand upright up to about 30 cm before the wall, since we are not that tall. Except for large wardrobes, everything can be placed (bed, dressers, couch, etc.).

Is there technically any objection to exceeding 2m, provided it is permissible?

Is there technically actually anything against going above 2m in terms of admissibility?

What already mentioned (at least I think that's what he meant). You have to consider beforehand what kind of windows you want. Beyond a certain height, roof windows no longer make sense. At least if you want to be able to reach them. Whereas for a "normal" window the height is not really sufficient yet. Especially if you add roller shutters or blinds boxes. Then you get window bands whose upper edge is at about 1.60m in height.
I've seen that a few times. From the inside, it's really strange. I'm 1.85m and have to bend down to look out. But some people don't mind that.
For me, either a knee wall, so that there are nice roof windows probably up to a height as already mentioned, or then as far as possible on a full story.

Is there technically anything against going above 2m in terms of feasibility?

Obviously not:

Our wall goes up to 2.65m, then the roof comes in at 22°. We don’t have an attic, but you can see the exposed roof structure from the inside, meaning the wooden boards and beams.

If necessary, the exterior walls on the upper floor must be braced better, since the upper floor/attic ceiling no longer serves to absorb tension forces. It probably also depends on the position of the interior walls as supports, but there are structural engineers for that.

The choice of knee wall height depends on the requirements of the rooms, the building regulations, and the personal taste of the homeowners. Ultimately, a good house can be built with any variant.