ᐅ Single-family house, single-story, knee wall, upper floor windows

Created on: 27 May 2016 19:05
M
molchi
Hello, good evening!

I would like to thank all active members and moderators here once again, as I have already received some good advice just by quietly reading along. However, we are currently struggling with questions that cannot, at least for me, be clarified on the internet.

Here is the situation:
Planning a single-family house with very tight specifications
Maximum house footprint: 121m² (1300 ft²)
One story
Lower Saxony

We would like to have a dormer on one side and narrow windows in the knee wall on the other side, if possible. Unfortunately, we have encountered conflicting information from architects, so I would like to ask the following questions:

Which parameters are taken into account when calculating the upper floor, in order to make the best possible use of the knee wall height?
The Lower Saxony building code states that a full floor requires a clear height of at least 2.20m (7.2 ft) over two-thirds of the floor area.
I also know that the external thickness of the gable wall is not included in the calculation.
Are there other factors that should be considered to maximize the upper floor area, such as stair openings, interior walls, or similar?
From what knee wall height or under which conditions are narrow windows on the roof slope side allowed on the upper floor, or are they impossible in a single-story building?

If you need any additional information about our project, please let me know!

Sorry for my non-expert terminology!

Good luck
Tom
M
molchi
28 May 2016 15:24
It should remain a gable roof house! Although a flat roof would also be possible. However, the building authority asked me not to do that!
Y
ypg
28 May 2016 16:28
Whether this is correct depends on the roof pitch.
L
Legurit
28 May 2016 16:42
I had the impression that interior walls are not counted. It is not about living area.
M
molchi
28 May 2016 16:42
Oh crap, yes, forgot to mention!

30 degrees Celsius (86 degrees Fahrenheit)!!
Y
ypg
28 May 2016 22:55
I would suggest moving away from focusing solely on the numbers and having an architect design a house that fits the floor area ratio and planning regulations.

Personally, I see little difference between a 160 cm (63 inches) knee wall and a full upper floor. With a well-planned upper floor for four bedrooms plus a bathroom, you can manage with about 80 m² (860 sq ft) of floor space.

You probably don’t need an expensive dormer if all four bedrooms are located in the gable ends and the central area is used for the staircase and bathroom. To gain additional floor space, you can also build a projecting bay window on the upper floor, of course keeping it under 2 meters (6 ft 7 in) in height—extending the pitched roof—which at least provides extra storage or space for play and seating.
M
molchi
28 May 2016 23:31
Hey!

The dormer is basically just a bay window since it sits flush on the exterior wall of the ground floor. However, it is higher than 2m (6 ft 7 in). Since two architects have already worked on it but arrived at different values for the knee wall height, I want to clarify this!