Survey of saddle roof knee wall height

Obviously not:

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

I also wouldn’t call 2.65m a knee wall. At least not what one classically understands by that. We also built it that way. But for me, that’s then two full stories. No idea if there is an official definition for that.

Well, I meant e.g. 2.25-2.3m. Then it would still be 2m window top edge with roller shutter box. OK, but actually not

I would like to ask purely out of interest if there are any builders here who have built a gable roof and deliberately did not set the knee wall as high as possible?

Yes, we have. According to the development plan, we have single-story buildings. Many with two children (or also for the look… many want the look of two stories) have pushed it to the limit in an urban villa style, knee wall of 180 or similar… We have 1.30 inside. I had no difficulty with that, as we didn’t urgently need the space upstairs and rather wanted less space there. So now the bed is under the sloping roof, pitch of 22 or 26 degrees (I don’t remember exactly). We are somewhat limited in the dressing room, but still have more freedom of movement than others with their narrow dressing corridors. With the low roof pitch, we also did not use the maximum height.

The traditional construction here is without a knee wall, which is why outside a maximum of 75cm and a gable roof of 35-45° are specified.

I like that and it is my preferred building method: you then have a bit more space downstairs, but the option for attic conversion with nice rooms and real windows. Basically, everything is possible.

For us, the wall goes up 2.65,

That would be a two-story building. Unfortunately, and this probably concerns you, the plots are getting smaller, so the floor area ratio restricts the builders in such a way that the roof slopes cannot be compensated by the floor area. Therefore, you already have to go up with your knee wall to reach the required sqm, even if it is only feasible through actual headroom clearance.

Sorry for having to ask a stupid question :D, but what exactly do you mean by that?

I can’t help it if you still ask stupidly ;-) (in the quoted post, I had named the title of the explanation, which you have to google yourself because of the local rules). has already correctly summarized essential parts of it. The knee wall height creates a dividing line similar to a high jump bar: facade windows in the knee wall must duck below it, roof windows must jump above it and then perhaps only illuminate your bald head. Windows on both sides of this dividing line in height require a dormer at the eaves and thus an eaves and ring anchor breakthrough or otherwise are only possible on the gable sides. The "window dividing line" knee wall is best placed, from the viewpoint perspective, at a height where a "beam in the eye" doesn’t bother you: that is, low enough so that the roof window sill is not at chin height (or high enough so that children up to the third grade can look out of the facade windows).

Is there actually any technical objection to going over 2m if allowed?

Similar to the window division, there is also a tipping point for the proportions of the cross-section — i.e., the gable-parallel walls of the attic — where the effect flips: namely between the positively perceived effect of high straight sides and the effect of "clipped corners." That is, up to a knee wall of in my opinion max one meter eighty, the impression of a high knee wall prevails, but above that, it then feels like a ceiling pushed up into the attic or a lowered roof slope like a hat pulled over one’s face. Unless you can avoid this with a roof soffit reaching up to the ridge. However, this can lead to very high rooms. I recommend for roof pitches in the range of 35/40° the combination "knee wall 100 to 140 with ceiling," and conversely the combination "open ridge with knee wall 180 to 220" with then about 20/25° flat gable roof. Mansard roofs unfortunately hardly ever appear in the minds of the garden gnomes in the committees that set development plans almost everywhere.

The "Fensterscheide" knee wall is best placed at a height, from the viewpoint perspective, where a "beam in the eye" does not disturb you: that is, low enough so that the roof window sill is not at chin height (or high enough so that only children up to the third grade can look out of the facade windows).

Classy and practical description, I’ll remember it just like that. To loosen up this "Fensterscheide," there are window arrangements that combine both a floor-to-ceiling knee wall window and a roof window. A line remains, of course, but the window sill is eliminated.

The room’s appearance can also be influenced by boxing in, for example, storage space or built-in furniture.

In some development plans it is possible to expand a room with dormers. This then depends on the described length and width ratios.

I didn't find it difficult since we don't urgently need the space upstairs and rather wanted less up there.

I honestly think that at 1.30 m you are hardly restricted at all when it comes to placing furniture. Almost everything fits underneath except a large wardrobe. But for that, I still have other walls in the rooms ;-) Our dressing room might be a corridor-like room as you described, but it has no sloping ceilings because it is on the gable side.