Calculation example attic knee wall

Hello everyone,

Is it possible to roughly estimate the additional costs of planning a knee wall instead of a dwarf wall?

Is it possible to estimate the cost differences for the following examples:

Single-family house
Gable roof
Dwarf wall
45-degree roof pitch

Vs

Single-family house
Gable roof
Knee wall 80cm
45-degree roof pitch
E.g. +5000€ more?

vs

Single-family house
Gable roof
Knee wall 1.60m
35-degree roof pitch
E.g. +10000€ more?

The remaining basic data such as the house exterior dimensions should remain the same in the three exemplary cases (except for the living area, which would naturally increase due to a higher knee wall)

Depends 100% on your builder and their surcharge policy. Building and plastering an extra row of bricks is not a big deal, on the other hand, a lot of good money is made with knee wall height increases.

Or basically the construction type of the knee wall. I don’t have anything built with masonry there, but a "wooden frame" on which the roof truss then rests. In the shell construction, 1m knee wall.

Or basically the construction type of the knee wall. I don't have anything made of masonry there, but a "wooden frame" on which the roof truss rests. In the shell construction 1m knee wall.

It should be prefabricated construction. So nothing masonry

I can only tell you that the seller from Weberhaus told us back in 2020 something about €2500 per 10cm of knee wall. Any windows in the high knee wall would of course be priced separately. In contrast, with our general contractor, there was about a €14k difference between a full and half storey (I would have to look up the exact height), windows priced like masonry. Just to give you a feeling for the difference

The knee wall refers to the exterior wall on the eaves side of a house, built above the rough ceiling of the top floor, on which the roof structure rests. It is a typical feature of purlin roofs. The higher the knee wall, the more floor space is available under the roof slope. Source: (exceptionally by me) Wiki

because tapering off results in a lot of floor space being lost in the attic. However, if a considerable amount of usable rooms have to be accommodated upstairs, the footprint on the ground floor would have to be chosen larger again. Nowadays, some plots no longer allow this (costs, size, availability). This may also cause an imbalance of the rooms between the ground floor and attic (too much downstairs, too little upstairs).

No words :(

the remaining key data such as the house exterior dimensions should remain the same in the three example cases, (except for the living area which would of course increase with a higher knee wall)

Then you are comparing 3 different living areas here and thus apples and oranges.