How bad is the condition of our building ground?

Hm interesting that you mention the sand... I thought it was actually advantageous because it is not cohesive and easy to backfill. I was more worried about the large amount of clay.

Hello,

You have mediocre to normal soil conditions that can be found at many building sites throughout Germany. The planner can plan the foundation individually based on the soil survey report. And what I see and what you write is absolutely within the scope of normal foundations. The problem rather comes from the fact that many companies enter the competition with total prices without knowing the local conditions. And depending on the provider, they assume foundation conditions that are sometimes nearly optimal. And these are found only in very rare cases in the soil. Therefore, the item for additional foundation costs is always listed in the cost estimate here in the forum. The house price can only be determined somewhat reliably directly on site. Everything before that comes pretty close to reading tea leaves. Difficult conditions are: ring foundation around wells, pile foundation, groundwater up to almost surface level, etc.

Hmm interesting that you mention the sand... I thought it was actually advantageous because it is not cohesive and easy to backfill. I was more worried about the large amount of clay.

I would have thought so too. Sand is great as long as it is compacted.

And I thought sand cannot be compacted, especially since in the north by the sea everything is built on piles because everything is made of sand.

We built directly on the slab. The topsoil was removed, sand was placed on it and compacted, Styrodur and glass gravel, then reinforced concrete and that was it. Strip footing would have been more expensive.

For this, the foundation slab is constructed with more reinforcement, which also costs money.