ᐅ Regulations Regarding Basement Construction?

Hello, we are currently in the planning phase for a plot of land that we intend to buy – the plan is to build a semi-detached house with a basement. However, due to some building regulations, we will probably have to build smaller than originally planned. Our idea was to fully extend the basement (for example, under the terrace), making it larger than the house above. Our architect said this is only partly possible, up to the maximum allowable floor area ratio. We had always assumed that the floor area ratio only applies from the ground floor slab upwards. Unfortunately, it is Friday evening, the architect is no longer available, and we urgently need an answer.

Could someone here possibly help? Are there size restrictions for basements?

Thank you very much
Kat

Hello Kat,

If you have your architect’s phone number, I can simply call tomorrow—if this question is really that important to you over the weekend.

Basically, it depends on which state or region you will be building in, which you haven’t mentioned here. The building code of the state (which you can check yourself on the state’s official website) defines from when a storey counts as a full floor. The basement usually only counts if it exceeds a certain size that is fully exposed. Often, you can adjust this with suitable backfilling. But you will need to find out exactly how much—meaning the percentage of exposure allowed—so that the basement does not count as a full floor.

Floor area ratio (FAR) is the ratio of the total floor area of all storeys considered. If the basement does not count as a full floor according to the local building code, then its total area is not added to the floor area ratio. In that case, this storey is simply not included in the calculation.

Thank you for the quick response. We are in Bavaria, so I will take a closer look at the regulations.

I don’t have his phone number, otherwise I would have already bothered him 🙂