Neighbor's concrete supports on our property

Hello, think about water, according to your description clay soil, in the sketch your terrace is the lowest point, the neighbor hardly has any infiltration area, in our neighborhood after heavy rain the basement was filled with 1m of mud, make sure the water flows around your house, have the neighbors reduce their construction Best regards Nida

I share these concerns as well. Certainly nice to arrange visually, but the terrace below the garden with various sealed surfaces in the immediate vicinity can quickly go wrong. Especially with the current weather conditions.

We plan to install a drainage channel between the natural stone wall and [OK Terrasse], I hope that is sufficient!

So, just chatted with the landscape gardener, they will probably tear it out! He is talking with the neighbor first!

Nothing will be spared for you either.

Building Code § 862 Claim due to disturbance of possession
(1) If the possessor is disturbed in possession by unlawful self-help, he may demand the removal of the disturbance from the disturber. If further disturbances are to be feared, the possessor may sue for injunctive relief.

§ 859 Self-help of the possessor
(1) The possessor may defend himself against unlawful self-help by force. ...
(3) If the possessor of a property is deprived of possession by unlawful self-help, he may immediately reacquire possession by removing the offender after the deprivation.
Or as Andrea Nahles would say: Then you'll get your ass kicked!

They will probably have to, if you insist on it and you definitely should.

Missing the point. Because the point "immediately" applies. But immediately is over. Now it's time to take the legal route.

So, just spoke with the landscape gardener, they will probably tear it out! He’s going to talk to the neighbor first!

Yes, he now wants to find out who messed up and has to pay for it
And the additional costs for the L-stones will be on top.