Property division - house sale + house construction on a new plot

Hello everyone,
I currently own and live in an old house located on a roughly 950m2 plot in BW.
I would like to build a new house in the near future. Due to the lack of building plots in my area, I have now come up with the idea of dividing my plot, selling the old house including that part of the plot, and building a new house on the other part of the plot, which I would then live in myself.
The current parcel can be seen here:



The garage is at the top left and the old house in the middle. The red line is meant to represent an approximate division. I would now like to sell the left plot (including house + garage) and build a house at the top right.

I have the following questions about this:
- I would like to carry out the plot division in favor of the “new” plot (right side). The distance to the boundary from the old house is 2.5m. Am I allowed to let the boundary run directly along the old house and not observe the 2.5m distance? I would like to do this in order to have a larger garden on my “new” plot. I am aware that I must provide a corresponding compensation on my plot for this and may not build directly on the boundary (which I don’t want to do anyway).
- How do I proceed with this plan and how can I find out if I am even allowed to build another house on this plot and what restrictions apply?

Does anyone have experience with this case and can possibly offer advice/tips?

I would very much appreciate feedback.

Best regards
Fabian

That cannot be answered with so little information. Is there a development plan for the area? Are there buildings in the second row? What about the floor area ratio? And who would want to buy the old house with such little attractive garden space if you are building?

That cannot be answered with so little information. Is there a development plan for the area? Are there any buildings in the second row? What about the floor area ratio? And who would want to buy the old house with such a small attractive garden area if you are building?

There is no development plan. In the street, there are no buildings in the second row, but there are in other areas of this town. I am not aware of the floor area ratio. By rough estimate, the "old" plot would have about 410m2, in my opinion still attractive enough. But of course, not quite as attractive as before.

This cannot be answered with so little information.

... and besides drawing simple lines on a site plan, it would be useful to dimension it in such a way that the individual sections like plot widths, widths of existing houses, distances required according to building regulations can be identified. If I look at the "proportional" based on the 28 m plot width, an estimated width of 5 m remains for a separated plot as drawn ... or you have to negotiate that you build with an obligation to add on in the "sense of a semi-detached house." Why are there actually professionals like architects etc. who can probably answer such questions based on the relevant basic information about the municipality, development plan, changes to the plan, etc., with expertise?

There is no development plan. There are no developments in the second row on the street, but there are in other areas in this town. I am not aware of the floor area ratio. Roughly estimated, the "old" plot would be about 410m2, in my opinion still attractive enough. But of course, not quite as attractive as before.

If there is no development in the second row on the street, this can be an exclusion criterion in a 34 zoning area. Only a preliminary inquiry can help you there.

If it is a 34 zoning area according to the building code, then how the surroundings have been built counts. That means the floor area ratio of a property or also virtual building lines. If you plan something zigzag like that, it is also advisable to provide measurements to see if the property is even buildable in such a way that you have a small sufficient house with some garden available to your satisfaction. Please measure it and upload a Google Maps excerpt where the neighboring buildings can be recognized.