Financial devaluation of one's own property due to the neighboring house

Written deliberately provocatively: For the small penalty fee of 5,000 euros, you can build your house one meter higher and then you will no longer have any disadvantages from the shadowing of your neighbor. Maybe you can share the costs with the neighbor

Now seriously:
Talk to your neighbor and the building authority about your problem/concerns and ask how they imagine a solution.
If necessary, it might really be a solution to build your house higher or the terrain will be adjusted accordingly.
Has your building application already been approved?

Written quite deliberately provocatively: For the small penalty fee of 5,000 euros, you can also build your house one meter higher and then you no longer have any disadvantages from your neighbor’s shadowing. Maybe you can share the costs with the neighbor

Very good Jochen But I still prefer to play it safe and build within the allowed height

You are considering claiming damages due to the depreciation you feel caused by the non-compliance with building regulations. Any claim on our part is based on claims. These can be found here in the Building Code. The identification will presumably only be able to rely on three legal grounds. §§ 280 and 823 I Building Code are excluded, since no obligation exists towards the neighbor under 280, and under 823 I financial damages are not covered.

Thus, only § 1004 Building Code remains. § 1004 I Building Code provides a claim for removal, which is limited in 1004 II in that it does not apply if you are obliged to tolerate it. Furthermore, it has emerged that the removal must also be reasonable, meaning it does not have to be carried out at any cost.

How does it stand here? The rascal simply (?) built too high and the municipality noticed and imposed a fine. At the same time, it did not order the dismantling, presumably due to the disproportion.

Of course, you can have any claims reviewed by a lawyer of your choice and try to enforce them. I do not want to spoil your fun, but I fear that this action will be as expensive as it is unsuccessful. In addition, the relationship with the neighbor (and possibly other neighbors) would be ruined forever, I would assume.

Swallow your anger and enjoy your beautiful home. The impairments really remain within limits, and a real financial disadvantage would only arise, if at all, when you sell the property.

Talk about your problem/your concerns with the neighbor and the building authority and ask how they envision a solution.

The problem is that there is no problem.

@ Jochen104: Yes, the building application has already been approved and the foundation slab has now also been poured. So raising our house is no longer possible. I have already thought about the possibility of a discussion, but I wouldn’t know what that should bring me. @ Voki1: Thank you very much for your detailed answer as well! You are saying what I have already suspected. I am probably just too annoyed that we are spending a lot of money to build a nice house and then a) are strongly restricted by the development plan and b) the neighbor also disregards the legal requirements to our disadvantage.