How do you calculate the knee wall height?

Good day,

can someone tell me how the knee wall is correctly calculated? I currently have offers from 2 developers, and both calculate differently.

Data

Knee wall 80cm
Roof pitch 38°
Wall thickness 36cm

1. 80 cm knee wall outside is approx. 100 cm inside
2. 80 cm knee wall outside is approx. 65 cm inside

Excerpt from development plan

The knee wall height (knee wall height)
of the attic must not exceed 80 cm. The knee wall height is defined as the
distance between the top edge of the attic floor and the intersection line of the outer surface
of the wall with the lower edge of the roof covering.

I am not interested in an exact value, but in which developer is wrong?!

Best regards

Chris

Inside with us, the FF was about the same as outside... The floor structure was slightly higher than the foot purlin. I believe the knee wall is the masonry height from the raw floor and then the geometry accordingly.

OK different!

What is the top edge of the attic floor?
- With screed and tile or without?

What is the bottom edge of the roof covering?
- Rafters outside or inside?

According to my logic, raw floor and the height of the built-up portion - so most likely the inner roof membrane. But it may also be wrong

Good day,

can someone tell me how the knee wall is correctly calculated?
I currently have offers from 2 developers, and both calculate differently.

Data

Knee wall 80cm
Roof pitch 38°
Wall thickness 36cm

1. 80 cm knee wall outside is about 100 cm inside
2. 80 cm knee wall outside is about 65 cm inside

Excerpt from development plan

The knee wall height (knee wall height)
of the attic must not exceed 80 cm. The knee wall height is defined as the
distance between the top edge of the attic floor and the cutting line of the outer surface
of the wall with the lower edge of the roof covering.

I am not interested in an exact value, but which developer is wrong?!

Best regards

Chris

No one has to be wrong, it is probably more about the floor area to be achieved; the one with the 65 knee wall will probably maximize the usable space and perhaps have a different wall construction than the one with 80 cm.

can someone tell me how the knee wall is correctly calculated?

You can find the calculation model in your state building code; one municipality considers the intersection with the outer roof skin as the standard, the next one the intersection with the inner skin. Each federal state does its own thing there. Rhineland regards