Garage height at property boundary on slope - average wall height

Hello,

In the development area where we bought a plot, another builder has registered a building encumbrance on an adjacent plot. He wants to place his garage on the property boundary. Almost all plots in the development area have a slightly sloping terrain downwards from the access road, as does ours. (approximately 1 to 2 meters depending on the plot) Therefore, he had his house and garage elevated by about 1.8 meters to be at the level of the access road. For the building permit of the garage, a building encumbrance on the neighboring plot was necessary.

The average wall height must not exceed 3 meters. We want to place a prefabricated garage with a flat roof on the property boundary. For example, 3.3m (wide) x 6m (deep) x 2.5m (high).

In the case of a plot elevation of 1 meter, do I have to add this to the 2.5-meter garage height or not?

... In the case of a land elevation of 1m, do I have to add this to the 2.5m garage height or not?

Yes, the embankment counts from the upper edge of the existing terrain.

I would like to address the topic. We also have a slope and want to place a garage on the boundary to the neighbor. The point about the average wall height, etc. is clear to me. We live in Hesse, so a permit is not even required. Due to the slope, we want to maximize the height. Now the questions.. The plot has already been raised along the boundary with L-shaped stones. Is this a problem if the garage is now next to the L-shaped stones, so it would no longer be exactly on the boundary? Could I also go higher, e.g. 3.2m, if I obtain a permit? Does the neighbor have to agree? And: How much "leeway" is there regarding the height? What if it ends up being 3.05m? What happens? Certain tolerances, and not exactly tight ones, do exist in construction, right? Is demolition threatened or what are the general procedures there?