Floor plan design: Single-family house with 4 bedrooms and an office, 160 sqm

I'll keep it short:
Get some help, the draft is flawed in many places. And you will only get comparable offers from home construction companies if you involve a professional (a.k.a. architect). Otherwise, you're comparing apples to Nutella and Hollandaise sauce.
(...)

Thank you for the hints!
We have not yet decided on a construction method (solid or prefabricated house). Would designs from an architect be independent of the construction method? Or should this be planned from the beginning?

As I recently mentioned in , floor plans suitable for families with three children can be found here, I believe, with

and with (where in the example by the plot situation with a rear property is also similar. And you can also nicely see that the "bay window" is absolutely avoidable if you design the staircase more compactly.

Thanks for the links, we'll take a look.

Many things have already been mentioned by .

I wonder what here is set in stone, and what is your wishful thinking.
With a high number of rooms, I always recommend a gable roof house for attic use.

There is no development plan, so we are free in the planning. We just like a hipped roof better. But I can also understand that a gable roof offers more usable space.

Hello and a nice Sunday, please also consider the roof area that you generate with a gable roof. This is better usable for photovoltaics.
Best regards Jasmin

There is no development plan, so we are free in the planning.

But that is also a misconception. Is there an official parking regulation from the municipality? Show us an aerial photo of the area around number 34 so we can somewhat assess it.

34 does not mean building however you want.

You need storage space. Fleet for 3 children. Toys, clothes that are handed down, seasonal needs. I find the utility room for technology, storage, and laundry far too small. It's already a shoebox with 2 functions.

Bay windows are not much cheaper than the house to enlarge the entire bay depth.

But that is also a misconception. Is there a parking space statute of the municipality? Show us an aerial photo of the surroundings around number 34 so we can judge it a bit.

Here is an aerial photo. The property is marked in red. You can still see the old building and the trees, which are now gone.

There are actually no further requirements after consultation with the municipality. Except, of course, §34 "Development is permitted if it fits into the surrounding development in terms of type and extent of the development, construction method, and the built-up area of the plot."

34 does not mean you can build however you want.

You need storage space. Fleet for 3 children. Toys, clothes that are passed on, seasonal needs.
I find the utility room for technology, storage, and laundry much too small. That's already a shoebox with 2 functions.

Bay windows are not much cheaper than the house to enlarge the entire bay window depth

I agree with you. We would gladly plan it larger as well, but then the footprint would also be bigger.
I now understand that it is probably more sensible to plan the house somewhat larger than to add an extra bay window. Maybe then the utility room can also be planned larger.

I have now understood that it is probably more sensible to plan the house a bit larger than to add an additional bay window. Maybe the utility room can also be planned larger then.

No. It would really make sense to have someone plan it who has studied this for years and has been working in the profession ever since. And please do not go with your own amateur plan, but with a list of what is important to you. He will then create appropriate plans for you that take your wishes into account and many things that have already been mentioned here.