Plot for building a single-family house - rocky soil

Hello everyone,

I would like to briefly introduce myself: We are a family of four from Middle Franconia and have been considering building a detached house (about 130 sqm) with a basement for some time.
Now, quite unexpectedly, the opportunity has arisen to purchase a plot of land privately. 550 sqm, slightly sloping (about 2.5 m across the diagonal), but the soil is not without problems. A soil report is in progress; after initial talks with the soil expert, soil class 6 is expected. Since our developer works "without extra charge" up to soil class 5, I would like to ask you for a brief assessment:

- What additional costs might we face? (Attached are one or two photos of the excavation for cable laying right next to the property)
- What other problems must/could we expect?

The neighbor built a basement and said that the rock could be removed with a large excavator at their place.

Thanks for your assessment!
Regards,
Volker

Hi, we had soil class 7 - rock. The excavator worked on the rock with a breaker for about two days.
We therefore had additional costs for the breaker hours (price per hour was agreed in advance, billing then based on actual time). The rock caused us additional costs of approximately €2,500.00 - I can't say the exact amount anymore.
Since we are not hauling away the stones from the pit but using them as edge reinforcement, we only incur costs for repositioning the ton-heavy blocks. If you cannot use them, the hauling away of the stones will be added...

But, our house stands rock solid

Best regards, Maxi

Hello Maxi,

thank you very much for your response! That doesn't sound so dramatic and is positive. Let's see what the [Bauträger] say.

Regards
Volker

Exactly, only the actual costs for additional excavator work are incurred (at least that would be the honest approach). But since you have rock chips and not chunks of rock, it wouldn't be that dramatic for you. The excavator probably doesn't care whether a stone is rock or soil, it’s just a bit heavier, but the excavator probably doesn’t care. However, it is probably more difficult for the bucket to dig in, so it could take longer.

When the time comes, it also makes sense to stop by and observe how easy or difficult it really is for the excavator.

And I would definitely reuse the stones in the garden as well. Elsewhere they cost money.