Purchase of land with existing building; new construction planned in the future

Yes, a combination of floor area ratio and the existing building line on the street from which we would otherwise deviate. It seems that there is currently no interest in densification and creation of living space...

At least not in this district.

From this I infer that you failed on the floor area ratio of 0.2 due to lack of development?

I would rather say that here someone gambled too high on suppressed corns. Why the OP did not accept the repeatedly given suggestion of dividing the homeowners’ association and the suggestion of a two-family house given at least by me with the sellers / front occupants does not become clear to me. Instead, saving demolition extra costs, I consider to be foolish.

Yes, a combination of floor area ratio and existing building line on the street from which we would otherwise deviate.

If I’m not mistaken, Dimeto also considered the deviation to be reasonably likely to succeed (?)

It seems as if there is currently no interest in densification and creation of living space...

Some municipalities / districts apparently have little fear of weight loss, and are more pleased about a declining student burden.

Yes, however we "have to" buy the front property now as well, otherwise we won't get approval for the building application due to buildability...

This information is interesting for everyone who associates you or your username with the rear property, turning problem, and specific smart home plans! Pretending that you are just a contact for participants and advisors here and will be forgotten tomorrow is a gross understatement.

I wouldn't put myself through renting out. If an early demolition causes problems with water and electricity, just demolish a bit closer to the construction instead of now? Instead of 5 years before, just 2 years before. Apart from classic renting, I can't think of anything more than parking fees for trailers, cars, etc. to make some money during the interim period..

I wouldn't put myself through renting. If an early demolition causes problems with water and electricity, just tear down a little closer to the construction instead of doing it now? Instead of 5 years before, just 2 years before.
Apart from classic renting, I can't think of anything else more than parking space rental for trailers, cars, etc. to make some money during the transition period.

Yes, that's what I had also considered. I hope the authorities won't cause trouble at some point regarding vacancy and "misuse" of residential space in such a case...

We are now planning to demolish directly and build new, and accordingly the question of earthworks arises: The current basement covers an area of about 60 sqm, about 1.5m below the top edge of the natural ground. This would result in a pit of about 90 cbm. The house or the new floor slab, however, would have a base area of about 110 sqm and only require excavation of about 60-80cm. How would one backfill here as cost-effectively as possible so that I can estimate the volumes and costs? Would one level the pit to a height level (60-80cm?) and then fill it with F1 sand? Or would one keep a kind of step in the pit and simply fill it with sand? How does this usually proceed in reality?