Knee wall height in a shed roof dormer

The search in the forum and on the internet has so far been unsuccessful, so I am asking the question here:

In our house construction project, the architect expects a "very low" knee wall when installing a shed dormer in the attic and has named a cross gable as a potential alternative. However, we don't really want this due to the appearance and shading of the ground floor. I wanted to understand the whole thing a little better and measured in our current rental apartment with a shed dormer:


I do not know the thickness of the rental apartment's roof insulation, but I am now simply assuming "current standard" (year of construction 2019). The windowsill in the dormer is about 27 cm higher than the knee wall, each measured from the inside at floor level.
Can it be assumed that with a lower knee wall, the sill height can also be linearly reduced by the same amount?

In other words: Would I get a windowsill height of about 117 cm with a knee wall of, for example, 90 cm?

The windows in the rental apartment are, in my opinion, way too high. For our own build, I am now looking for the sweet spot between "sufficiently high knee wall" and "sufficiently deep dormer windows."

I am grateful for any assessment (or experience reports, in case anyone wants to measure at home).

For our house construction project, the architect expects a "very low" knee wall when installing a shed dormer in the attic and has mentioned a cross gable as a potential alternative. However, we are not really keen on this due to the appearance and shading of the ground floor.
I wanted to understand this a bit better and measured in our current rented apartment with a shed dormer:

The structure in your illustration is not a shed dormer, but a shed cross gable.

Can it be assumed that with a lower knee wall, the sill height can also be reduced linearly by the same amount?
In other words: If I have a knee wall of, for example, 90 cm, do I get a window sill height of approximately 117 cm?

With the same roof pitch and the same wall thickness, that would be the case.
I recommend my post "How the Knee Wall Influences the Window Question in the Attic".

Thank you for the prompt response! It is not clearly shown in my drawing, but below the dormer there are still 1-2 rows of roof tiles. On the eaves side, the gutter is therefore continuous. In this case, is it still called a dormer instead of a "real" dormer? Visually, I imagine it something like this:

I have a knee wall of 86 cm and a windowsill at 104 cm. However, there is only insulation between the rafters. The basis is the finished floor. According to the development plan, we had a 1 m knee wall from the raw floor. Since your roof seems thicker in my opinion, your knee wall should be a bit smaller. 75 cm, then you probably have the 1 m windowsill height. But you can also go one row of roof tiles lower with flashing.

It is not clearly shown in my drawing, but below the dormer there are still 1-2 rows of roof tiles. On the eaves side, the gutter is therefore continuous. In this case, do you still speak of a transverse dormer instead of a "real" dormer?

Yes, it is clearly visible both in the drawing and in the picture that the "roof" on the valley side of the supposed dormer is merely a roof overhang. Transverse dormers and dormers differ only "genetically", i.e., to which category such a roof structure belongs depends on the construction: a dormer always sits on a knee wall, a ridge beam, or otherwise on the upslope side of the knee wall; while a transverse dormer—whether with decorative apron or not—always grows up from a knee wall. I have already added this accordingly to the "Construction Terms Glossary" / "Building Dictionary" earlier this morning.

All right, learned something new again!

You can also go one row of roof tiles lower with a metal flashing.

The metal flashing would then be an extension of the exterior windowsill, if I understand you correctly? Then you could position the window lower. The view from the dormer window downwards will probably not be necessarily easier because of this, but it is certainly an option if you want/need to squeeze out a few more centimeters.