1 big house or 3 small houses?

Popcorn + Cola already prepared?
(Have to mow the lawn first...)

1. What do length and width mean to you? Please define clearly.
2. Open construction means maintaining boundary distance, at least for a group of houses on the right and left.
3. Consult the development plan to see what is allowed - if open construction with a single-family house, then no three apartments and no group of houses, etc.
4. Parking spaces absolute minimum three pieces, preferably and regularly two per apartment/house.
5. A group of houses with three houses means three small houses.
6. Present the development plan here.
7. Present the site plan here.
8. Explanation of what you actually want to achieve. Why? Houses have a terrible return.

Please simply work through this and then wait for answers. They will come, even if you might not like them ;)

It is about the following: 3 children have inherited a 500 sqm (approx. 33 m x 15 m) plot of land. Building-ready land. The basic question is: Do you build a 3-family house, or 3 small houses?

Whatever the layman assessment "building-ready" may mean, 500 sqm of building land and three residential parties result at best (site coverage ratio 0.4 / floor area ratio 0.8) in 440 sqm of living space with at least five parking spaces. I would say: don't waste any thoughts on fantasies, go to the bank. I see at least one of the three children being paid out here, but not all three building.

"Buildable land" is stated as such in the development plan. The floor area ratio should be 1, but it is not stated in the online available development plan. The site coverage ratio is definitely greater than 0.4 on all neighboring plots.

By width I meant the side facing the public street.

There are semi-detached houses on the neighboring plots, each semi-detached house (i.e. the whole) is definitely on a smaller plot than 500 sqm.

One of the 3 children would also be satisfied with a smaller living area, let's say 70 sqm.

Is a house with 3 floors really so unrealistic, if the development plan does allow it?

Are you sure you want to live door to door with your siblings for a lifetime?

Just because your neighbors have built more than the floor area ratio of 0.4 does not mean that the land-use plan says floor area ratio > 0.4.

Is a house with 3 floors really that unrealistic, if the development plan allows it?

No, it is not impossible. However, there is no point in guessing riddles here at all. If you really want help, you have to show us the development plan.