Building height of 8.5 m with basement and 2 full floors

It is like this:

[*]8.5 m "building height" from top edge of basement floor slab.
[*]Building with basement + 2 full floors are thus "forced" to have a flat roof.

That would be a masterpiece of foolishness and a perfect setup to overturn the development plan.

But I rather believe an apprentice was on the phone. Development plans are meant to unify the appearance of an area, and not create a restless skyline by capping the height of houses with basements.

We have leveled the plot privately.

What do the textual provisions say about height references to unaltered terrain and about limits of such terrain modifications?

It is like this:

[*]8.5 m "building height" from the top edge of the basement floor slab.

That is indeed unbelievable! Unfortunately, once again a case for lawyers. Here is my assessment:
This interpretation will not withstand judicial review. The term "floor slab" alone violates the requirement of definiteness, since further explanations such as "floor slab of the lowest storey" are missing. Even with that, there would still be a lack of definiteness, because the reference point must be determined or determinable in the plan itself, as it is for the reference point of the eaves height. Here, however, the reference point would depend on the architect’s planning.
Also completely unclear is the urban planning purpose of this stipulation. I would be curious about the wording in the justification. The possibility of a height determination aims at design influence on the townscape, which is definitely not achieved with this stipulation, and not at limiting the built-up volume. Other means such as plot ratio/floor area ratio/BMZ are available for that.

For you, the question now is whether you want to pursue legal action if the building application for your dream house is rejected. Are there still no houses in the building area? Do you know other builders there? Have you ever talked to an architect?

We measured these two points.

There is only one point. You determine the midpoint of your street-side boundary (which admittedly is not quite clear with your plot shape). From there you take the shortest way to the street center (I then arrive at point 258.81). The eaves of your house may be a maximum of 6 m above this point (so a maximum of 264.81 above NHN), completely independent of the terrain heights on your property. Although this stipulation is also likely to be challengeable (see judgment OVG NRW, 28.08.2014, Az.: 7 D 8/13.NE).

That would be a Schildbürger (master) prank of the highest quality and a perfect setup to overturn the development plan.

But I rather believe an apprentice was on the phone. Development plans are meant to standardize the appearance of an area, not to create a restless skyline by capping the height of basement houses.

In my opinion, the office has 3-4 employees. On the phone, I spoke to a colleague of the lady who created the development plan (she was on sick leave). He was familiar with the situation, as builders before me who have built in the area had this problem.

His summarized statement in roughly quoted wording: "We are aware of the problem. Unfortunately, we can only offer you the option to go through an exemption application. However, it would have a good chance of being approved. Just make sure you don’t exceed 8.5 m too much." When I asked what "too much" means, he said up to 9 would still be okay. Our dream house plans a value between 10 and 11.

What do the textual regulations say about the height references to unchanged terrain and the boundaries of such terrain modeling?

I found nothing on that. As before Escroda, I will send you the plan once via PM.

The question for you now is whether you want to pursue legal action if your dream house building application is rejected. Are there no houses yet in the building area? Do you know other builders there? Have you already spoken with an architect?

The building area is about 75% built up to this day. I don’t know any builders and unfortunately live 300 km away. But I know from the city planning office itself that especially builders "in the hollow," meaning all building plots downslope (northeast), had to deal with this problem. Our neighbor has now built a huge house without a basement (hardly any garden left). Across the street, there is a small house with a basement (in my opinion, too small). Both have families. I would NEVER have built like that!! Whether that is related—quite possible?!

We are currently researching architects. I have been in contact with one since today.

(I then come to point 258.81). From there you take the shortest path to the middle of the street (I then come to point 258.81). The eaves of your house may be no higher than 6 m above this point (thus a maximum of 264.81 above NHN), completely independent of the terrain heights on your property.

So just to make sure I understood correctly: the eaves may NEVER be above 264.81 above NHN? Since the terrain slopes down about 1 meter from the planned house footprint, this would mean that my basement may protrude up to 1 meter out of the ground on the downhill side. But the uphill side of the building must be underground. And since the basement cannot count as a full story, about 3/4 of the basement would be underground, and from the last quarter there would be a slope exposing the basement up to 1 meter (where the office and guest room are located, with normal windows facing the garden).

I know from the Office for Urban Planning itself that especially builders "in the depression," which are all building plots downhill (northeast), had to struggle with this issue.

It is astonishing that all architects complied with this nonsense. I would first take a close look at all existing buildings on site to find out whether everyone really adhered to the regulations or how far they deviated.

just to make sure I understood it correctly

You understood that correctly. I just want to repeat that this regulation is also not legally compliant. But which builder has the time and money to take action against such amateurism.

Surprising that all architects have succumbed to this nonsense. I would take a close look at all existing buildings on site to find out whether everyone has really adhered to the regulations or how far they have deviated.

That will be easy. As soon as one of the almost 20 buildings already constructed has a basement + 2 full stories and no flat roof, the builder has probably clearly exceeded the 8.5 m here. Since I live 300 km away, I'll have someone from the family drive through the construction area over the weekend and assess the situation.

You understood that correctly. I just want to reiterate that this regulation is also not legally compliant. But which builder has the time and money to take action against such amateurism.

Thanks. What exactly is not legally compliant about the specification of 6 m eaves height as well as the reference point to the middle of the street? Or to put it differently: What changes in the development plan would need to happen to legally specify the eaves height? Just so I can also argue accordingly..

I was referring to your shortened quote, from which it is not clear which street must be referred to. In the original, the traffic areas are labeled "A" and "B", so only the somewhat subtle criticism of the not clearly definable center of the property remains. Since the height difference of the reference point will be less than 10cm depending on the method of determining the midpoint for your property, the argument in court would be somewhat weak. However, this does not refer to the nonsensical determination of the building height of 8.5 with the reference point floor slab. In my opinion, this represents a blatant violation of the principle of definiteness, which could lead to the nullity of the [B-Plan].