Basement construction, cement costs, floor slab, reinforced concrete walls, ceiling

Hi everyone! I have purchased a developed plot and am struggling with the plans for the expansion of the existing, but very small building. I would like to add a basemented extension, but I would first like to know roughly what costs I can expect. It would involve an excavation of about 4x5m to a depth of 3.50m. Due to the slope situation, I would probably have to use reinforced concrete made of water-repellent material on two sides to prevent unwanted water ingress. I have already considered costs for a staircase and an excavator, so I don’t need those for now. I will use the excavated material to fill another part of the plot, so transportation would not be necessary. But what can I roughly expect for cement, the floor slab, reinforced concrete walls, and ceiling?

I would really appreciate a tip. Please don’t hesitate to ask questions if you have any.

Thank you in advance

Sebastian

Hello Wandler,

unfortunately, I can't tell you anything about the costs, but I would advise you to use water-repellent concrete everywhere. Because even if the water only comes from one side, it can still penetrate all around.

Regards