Are empty conduits and empty boxes in WU concrete dangerous?

Hello everyone,

We are currently having an extension built onto the existing building. The extension is basemented and is also intended to serve as living space. The basemented area is largely (except maybe 50-70cm) below ground level.

Planned are a studded membrane, 12cm perimeter insulation, and 24cm waterproof concrete with double reinforcement. (Formed and poured on site). A drainage system is also planned. According to the construction company and the architect, the empty conduits and empty boxes are not a problem.

Should I, to be on the safe side, nevertheless refrain from the boxes and conduits or insist on an additional protective layer from the outside? Would a bitumen layer possibly be helpful here?

Best regards

Should I do it to be safe

Safe for what or against what?

How is that supposed to work at all? You have the formwork, where do you want to lay empty conduits there? And retrofitting is a huge amount of work, but you would have 4 cm of space. Since 20 cm is sufficient.

For safety, for what or against what?

To prevent water infiltration from the outside or from the ground. (Although we still have drainage.

How is that supposed to work at all? You have the formwork, where do you want to lay empty conduits there? And afterwards it’s a huge job, but you would have 4 cm clearance. Since 20 cm are sufficient.

Okay, these deep combo boxes won’t work then, the ones that are 6 cm deep.

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

Slotting minimally executed (I believe around 25 cm) [WU-Beton] is tricky. You can either make the [WU-Beton] thicker around the planned box depth but then you have to live with the curses of the electrician who has to chisel those slots. Or you make an installation level from drywall on the exterior walls, into which the boxes are then installed. Both methods incur costs. Anything else endangers the water impermeability of the wall. PS: An inexpensive alternative would be baseboards with surface-mount boxes. Or you completely forgo boxes and cables on the exterior walls or only install a mix of surface-mounted and baseboard wiring.

Or you can also install about 4cm Styrodur boards inside and have them plastered. That way you can also accommodate the electrical installation.