Single-family house with bay window on ground floor and upper floor -> Basement floor plan?

Hello everyone,

We are currently in the initial planning phase for the construction of our single-family house. So far, I have tried various floor plans and have come across the following question. If you build a bay window on the ground floor and upper floor, how do you proceed in the basement (the basement should be insulated for a separate apartment)? Do you use the same floor plan as on the ground floor, or do you make sure the basement is rectangular and build a floor slab in the ground floor as the base for the bay window? Or is it an option to use the outer wall of the bay window and thus get a larger rectangular basement? Here I wondered how the insulation of the basement ceiling looks, which is no longer under the ground floor.

Thank you very much in advance!

Whether to start a bay window already in the basement is all the more irrelevant the flatter the property is. A basement larger than the ground floor – even if only partially – is not advisable in my opinion. In a more concrete example, your question could possibly be discussed more satisfactorily.

Thank you for your response. That already helps me! The plot is almost completely flat. Over 20m length, about 1m height difference. I was just wondering whether a rectangular basement is more cost-effective than one with a bay window or whether it doesn’t make much difference. Attached are 2 floor plans. One is the basement with bay window and the other is the rectangular basement whose wall "cuts off" the bay window in the ground floor. It is always the ground floor; the less visible walls are those of the basement. PS: The length of the house is 13m.

Basement-ing the bay window is more complex - but bay windows always cost extra and should have a good reason on every floor why they are "needed". What do the rooms mean (including in the basement)? Present your project completely (with completed questionnaire, plot, etc.).

I am working out the floor plans of the individual floors and will then post them. I will be happy about any comments :)

What exactly do you mean by the questionnaire?

What exactly do you mean by the questionnaire?

https://www.hausbau-forum.de/threads/leitfaden-zur-hausplanung-auf-dem-Grundstück.30891/