Living area with step

Thank you for giving me so much credit.

Here ( ) there is an indication of about €9000 for 100m². In my case, it’s about excavating half (50m²) 10-15cm deeper than already planned. A simple explanation of how the €10-15k roughly adds up would also have helped me.

The explanation of how high the actual additional cost is and how the surcharge is composed can surely be obtained from your construction company. They will then be paid for it or at least have the chance to be paid for it. Whether it should be 9K€ instead of 10-15K€ or due to poor ground conditions even 17K€ should not play a role at this stage of idea development. That only becomes interesting when the offer is on the table and you realize that the budget does not fit the house. Then it means either cutting wishes, starting the planning from scratch and building something smaller, or completely giving up the house building topic.

Thank you for giving me so much credit.

You're welcome. I always respect skilled professionals!

Here ( ) there is an indication of about €9,000 for 100m². For me, it’s about excavating half (50m²) 10-15 cm deeper than already planned. A simple explanation of how the €10-15k roughly adds up would have helped me as well.

This thread deals with the pure earthworks for a "normal" construction project; regardless of the fact that the thread dates back to 2012. You want to install a split level; meaning, one level lies lower/higher depending on the viewer’s perspective. Since building is only allowed on undisturbed ground, the "damage" (due to required working space) to one level (here: the lower one) must be repaired by recompacting the soil. Only then can the next level (higher) be poured. This means the floor slab cannot be cast in one pour and therefore requires additional costs of the stated amount; depending on the soil conditions. Rhineland regards

I think that settles the matter. That's a lot of wood for a superfluous but nice level.

I guess that settles the matter. That's a lot of effort for an unnecessary but nice step.

Good! As already said: no step in a traffic area! A good architect will not plan that for you!