Are empty conduits and empty boxes in WU concrete dangerous?

Would you still recommend coating an exterior wall made of waterproof concrete (WU-Beton) from the outside, e.g. with bitumen, or would that be counterproductive for WU-Beton?
(There will be perimeter insulation applied on top)

Do you have groundwater? So you don't have to. We waived that. As additional security, it's not wrong. However, the myth of vapor diffusion without bitumen is history after many studies (fulfilled from 20 cm on).

By now, I would do it, since you can use it as an adhesive for the XPS boards right away. And you can also do this work yourself quickly with a trowel. Costs without labor are certainly 1500 euros for material.

As additional security not wrong.

According to the contractor, bitumen is not necessary and unnecessary. Still, I would feel better if it is not counterproductive with a white tank. Such a WeberSuperflex 10 costs about 100 euros per 30L and would be enough for about 6 sqm. For the extension, that would be 5-6 buckets.

Is a primer (regardless of whether it is an extension or an existing building) generally recommended?

So it is certainly not counterproductive. As I said, your construction contractor is right, but I see it the way you do. And still, out of 10 houses, probably 8 are made with bitumen. So it is very common.

Thank you. Nevertheless, we have now coated the extension with a thick coating, even though the contractor trusts his WU concrete and said the coating would not be necessary. By the way, I have read a lot of positive things about this Superflex 10. However, part of it had to be coated yesterday. I couldn’t find this Superflex 10 in the area. I then got the "Sopro KMB 651 Flex-2-K" from a specialist store. How would you rate this product? Can it be used without hesitation? (Especially since the price on the internet is about 70 euros. I got the bucket at the specialist store for 40) and I was confused, hoping the product is not inferior.

Our general contractor refused to carry out plumbing or electrical installation on the exterior walls of the white tanks.