Estimated expansion costs for the general contractor construction project in Berlin

For fences, something simple would be enough for us, about 1.5m high, above all durable

What is something simple?
In the building area, around 10k was paid for a roughly 50m long wooden fence, about half of which was for the material. It doesn’t look particularly special now either.
And some have metal railings for individual sections, which cost 1000€/m.

I would definitely keep your amounts as a precaution, but think that the floors could be 10k cheaper, while the outdoor facilities might be about the same amount more expensive.