ᐅ Possible Extension to an Existing Property

Created on: 23 Aug 2024 08:07
T
Tobilayo
Hello,

I know that users who register just to ask a question are not always welcome in a forum. But maybe someone will find a moment to answer my question.

We are planning an extension on the east side of our property (expanding the kitchen and adding an extra room, total 20.05 m² (216 sq ft)). Our property consists of four units.

The 1977 German Land Use Ordinance (Baunutzungsverordnung) applies, and we are located in Lower Saxony. The floor space index (Grundflächenzahl) is 0.3 and the plot ratio (Geschossflächenzahl) is 0.5.

According to my calculations, this is possible because the 1977 Land Use Ordinance only includes the main building and ancillary facilities connected to the main building in the calculation of the floor space index. Garages/carports are only included if they exceed 0.1 of the plot area.
We have received approval from the other three co-owners for the extension.

My questions:

1. Floor Space Index (Grundflächenzahl):
According to the 1977 Land Use Ordinance, garages and carports only count toward the floor space index if they exceed 0.1 of the plot area. The building authority staff member has now added up the square meters of all four carports and concluded that it exceeds 0.1 of the plot area. However, he also included the sheds located behind the carports. That can’t be correct, can it? I am attaching a photo showing which sheds I mean (marked in green).
According to the 1977 Land Use Ordinance, sheds/garden huts/bicycle storage do not count toward the floor space index or the 0.1 limit. If I exclude them, the total is below 0.1 of the plot area.

2. Plot Ratio (Geschossflächenzahl):
He simply took the external dimensions of the ground floors of the two houses and multiplied that by 2.
But the plot ratio should be based on the usable floor area, which differs between the ground floor and the first floor — basically excluding external walls, only the usable area counts. He probably chose this simplified approach because it still results in a value below 0.5 (0.491).

It would be really helpful if someone could assess these two points.

Thanks in advance and have a great weekend!
Grundrissplan eines Wohnkomplexes mit zwei Häusern, Erdgeschoss, Wohnungen, Garten, Carport.
Y
ypg
23 Aug 2024 09:32
Tobilayo schrieb:

Are you sure about that?
No. I believe that exterior walls are not included, but interior walls are. The term used is gross living area.
Schorsch_baut schrieb:

architect in charge of planning
They’ve probably already handed over the planning responsibility.
T
Tobilayo
23 Aug 2024 09:43
Hello, thank you for the responses. So far, I have been researching the topic extensively on my own and am trying to clarify as many things as possible by myself.
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nordanney
23 Aug 2024 10:00
ypg schrieb:

No. I believe that exterior walls are not included, but interior walls are. The term used is gross living area.

Sorry. Just believing that doesn’t help.

Take a look at the regulation from 1977

Textual building regulation for determining the floor area based on exterior dimensions, stairwells.

The enclosing walls = exterior walls are included.

This is still the case today. Floor space index / full stories = exterior dimensions.
Maybe you are mixing things up; floor space index has nothing to do with gross living area.
Y
ypg
23 Aug 2024 10:02
nordanney schrieb:

Sorry. Just having an opinion is not enough
That’s why I referred to our professional expert
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nordanney
23 Aug 2024 10:11
ypg schrieb:

That’s why I also referred to our specialist.
Fortunately, it worked out in the end. It’s a pity that one can’t be more straightforward here.