Strip foundation and earthing correct?

What exactly do you mean?

Someone has to register your new house with the electricity provider, and it must be confirmed that the electrical wiring and grounding have been carried out according to the regulations.

Oh, then it's probably more of a ring earth electrode, yes. It's laid as a ring in the strip foundation, and connected to it is a 10mm V4A round steel laid to the potential equalization rail. I don't have a complete black tank. I have a studded membrane under the strip foundation, and I get perimeter insulation under the base slab. I believe that thus the only part touching the ground is the sides of the strip foundation.

The ring earth electrode lies outside the foundation and, to my knowledge, is only allowed if a black/white tank exists... otherwise, a connection must exist every 20 cm...
Why you have a studded membrane underneath there is not entirely clear to me, but well, it doesn't damage anything either...

Registering with the energy supplier usually cannot/must not be done by just anyone but must be done by a registered electrical contractor – of course, the supplier lays the cable for you, but you are not allowed to connect anything there without registration (can also become expensive if...).

so we (construction company) normally lay the earth once around the ring in the foundation directly on the ground without foil. With foil, I would additionally "introduce" it into the ground using a 1m stainless steel earth rod. That’s how the electrician wanted it for a multi-family house. For that, the earth had to be fixed to the basket with a clamp every meter. But to be sure, I would maybe get the correct facts again from an electrician you trust. Unfortunately, I can’t tell you exactly what is according to DIN and standard.

I spoke with a master electrician. He also said that the grounding conductor should be connected to the reinforcement cages every two meters. However, if the measurement shows a correct resistance of the grounding conductor against earth, this would be acceptable. The firmly concreted foundation ground rod cannot rust away, and the connection of the grounding conductor with the V4A connection flag (which is connected to the potential equalization busbar) cannot come loose, as it was firmly embedded in the concrete.

I will now first commission the measurement and then we will see further.

Thank you very much for your answers.