Divide the plot in half or change it from a single house to a duplex?

Hello everyone,

I have a general question regarding plots of land and construction.

Assuming you buy a large plot of land on which you could easily build a semi-detached or terraced house. However, the building permit only allows for single-family houses. Is it realistically possible to achieve a change or will that be difficult?
Would it be easier to divide the plot into two or three with single-family houses each? Or would this fall victim to the same difficulties?

A bonus question maybe: If you divide the plot, can you actually agree with the neighbor not to observe the distances to the property boundaries? Or is this dictated by the city and the owners are not allowed to agree? I thought I once heard that you can build up to the property line if the neighbor has no objection and you, for example, pay them compensation.

Thank you very much for your help

P.S.: The title was once clearer but was too long for the forum software.

However, the building permit only provides for single-family houses.

Which building permit? You are allowed to build what is approved. Minor changes that would also be exempt from approval afterwards according to the state building code are generally possible, but changing from a single-family to a semi-detached house certainly requires a new permit.

Can one realistically achieve a change or will it be difficult?

Since we do not know the reality on site, this will be difficult to answer.
Is there a development plan?
When did it become legally binding?
What exactly does it stipulate (graphic and textual part)?
Are there comparable houses in the immediate vicinity?

Would it be easier to divide the plot and make two or three out of it, each with single-family houses? Or will this fall victim to the same difficulties?

We need facts, facts, facts ... site plan, floor plans, development plan, explanation of your understanding of single-family and semi-detached houses.

Is it actually allowed to agree with the neighbor, for example if you divide the plot, not to comply with the distances to the property boundaries?

Yes.

Or is this dictated by the city

Yes.

the owners are not allowed to agree?

The owners and also the proprietors can always agree. Whether this agreement complies with the applicable regulations there is examined in the building permit procedure or, in case of exemption from approval, is the responsibility of the draftsman.

I thought I had heard before that you can build on the property boundary if the neighbor does not object and for example you pay them compensation.

... and planning law does not oppose this.
So first check which planning law applies - development plan (§30 Building Code), neighbor construction (§34 Building Code) or outer area (§35 Building Code). For example, if there is a fairly new development plan that only allows single-family houses, the agreement with the neighbor is of no use because this only enables building regulations relief, e.g. in case of distance violations, and an exemption from the provisions of the development plan is highly unlikely. Popular solution: ideal division according to WEG ... but facts, facts, facts are missing.

The building permit only allows for single-family houses.

Are you perhaps confusing building permit with development plan?

P.S.: The title used to be clearer, but it was too long for the forum software.

But in the initial post you could have named the planned title in full length, clarity never hurts in a discussion.

Suppose you buy a large plot of land on which you could easily build a semi-detached house or a terraced house. However, the building permit only allows single-family houses. Can you realistically achieve a change, or will that be difficult?
Would it be easier to divide the plot and make two or three out of it, each with single-family houses? Or would this fall victim to the same difficulties?

So you assumed a plot of land with a building envelope for a semi-detached house (two-unit terraced house) or even a three-unit terraced house, but the development plan does not permit E/D (and certainly not H), only E. For example, if it allowed 2 residential units per plot, you could build a semi-detached house on one plot, and for a three-unit terraced house you would then have to place the third unit on a subdivided plot. However, in this thought experiment, this would no longer be a third terraced house, but a semi-detached house and the third terraced house would be freestanding next to it, with six meters (or in BaWü five meters, more precisely: in all federal states 1/2 H and only at least the mentioned colloquial standard values) of building setback in between. Where a formal semi-detached house is not allowed, you would have to build a de facto semi-detached house (in the sense of two horizontally connected apartments) as a legal single-family house (which does not exclude a break as a set-back or projection in the facades).

One bonus question maybe: If you, for example, divide the plot with the neighbor, are you allowed to agree not to comply with the distances to the property boundaries? Or is this stipulated by the city and owners are not allowed to agree? I thought I once heard that you can build right on the property line if the neighbor has no objection and, for example, you pay him compensation.

Regarding the six or five meters (or more precisely: 2/2 H) clearance between the houses, it does not matter whether the garden fence is in the middle. The additional distance the neighbor keeps on his fence side ("takes over") is negotiable (between you, largely at will), but the municipality is strict about the total house separation, which cannot be changed. The only thing you can compensate the neighbor for is the part of the setback obligation that he is willing to fulfill on his property so that it can be considered fulfilled overall. As mentioned, the total width of the setback is not shortened by this. So you cannot agree among yourselves to waive the distances altogether; you can only redistribute the total, strictly enforced distance between each other—and even then only bilaterally, not with three parties involved. If for your assumed plot the statement "two or three houses will fit on it" only holds under the assumption that the distances between them may be omitted, then for a horizontal two- or three-family house you would need two or three permitted residential units on the undivided plot. The difference between two single-family houses and a semi-detached house according to the development plan is only that, in the semi-detached house allowed by the development plan, the usual setback obligation on the common property boundary is replaced by a unilateral obligation to build attached. Where a development plan designates single-family houses (E), single- or semi-detached houses (E/D), or terraced houses (H), this is generally a planning goal that would be structurally undermined if it were relaxed wherever two neighbors said, "we would rather each build one building setback wider; giving up one side with windows would be worth it to us." In that case, the development plan could be scrapped spatially from the outset, as given the current land prices, almost only semi-detached house developments would then be desired. However, a development plan is not a wish list concert; otherwise, its function as an element of land sealing control would be lost.

Thank you very much for your feedback

Unfortunately, I do not have the documents. The information so far is only second-hand. The statement is that currently only detached houses are allowed to be built. There are residential buildings with multiple units in the neighborhood, but the houses directly around the plot are all detached houses. Of course, I would like to provide more facts, but unfortunately I do not have them.

Do building permits not expire automatically after 3 years? I thought they expire anyway. Is a development plan then permanent? So, if a plot is only to be developed after, for example, 20 years, does the development plan from 20 years ago still apply? The plot has been vacant for several years.

If the sum of the distances must be maintained, but otherwise bilateral agreements are allowed, would it then be possible to build the houses almost like a semi-detached house next to each other, as long as enough distance is maintained on the other side? But one would not be allowed to build a semi-detached house on these two plots together? In other words, acquiring two plots and placing a semi-detached house on them (with a shared wall basically on the property boundary) to create more space on the opposite boundary?

However, the building permit only allows for single-family houses.

Which building permit?

Do building permits not automatically expire after 3 years? I thought they expire anyway. Is a development plan then permanent?

So, if a plot is only to be built on after, for example, 20 years, does the development plan from 20 years ago then apply?

You should think a bit about what you write if people are already asking what you mean. You are mixing up terms.

A development plan prescribes what is allowed and what the plot may be used for.

A building permit is obtained when you design a house and submit the application to build, i.e., the building application, and later receive approval from the municipality, i.e., a building permit.
In a new development area, there are structures of single-family houses in one corner, semi-detached houses there, and then multi-family houses on the edge. Usually, the plots for the single-family houses are roughly divided in size as prescribed by the district (or something like that) as the minimum size. For example, in our area, they have to be 650 [square meters]. Only if the use in the development plan allows semi-detached or terraced houses can you deviate from this.
Usually, you have to build within 3-5 years in a new development area so that living there is not disturbed by construction noise after 5 years. If this requirement does not exist and you want to build later, you just submit your building application later because the permit is only valid for 3 (or so) years.

Maybe you should simply describe your problem instead of beating around the bush; then you'll also get good information. Because whether and how a plot can be built on involves several rules working together.