Loess Loam & Shell Limestone as Building Ground: Unexpected Expenses / Costs

Hello dear forum.

We have the prospect of an approximately 600 sqm building plot in a new development area near Rottweil in Baden-Württemberg (border of Black Forest / Swabian Alb). It is connected at the edge of town to an already established residential area and comprises about 30 building plots. The area was previously meadowland.

The report on building regulations, the building plot offer, as well as the notarized contract, which we already have, list soil conditions that we (even after extended internet research) do not understand. These are listed in bullet points as follows:

[*
Building area in the geological region of the middle Muschelkalk
[*]Quaternary loose rocks (loess loam) of unknown thickness expected as building ground, with rocks of the middle Muschelkalk underneath
[*]Partially geogenic contaminants such as arsenic, cadmium, lead, etc. cannot be excluded
[*]Disposal of potentially excess earth masses may therefore be more expensive
[*]Localized varying subsidence behavior is to be expected
[*]Possibly present organic components may potentially lead to construction-related complications
[*]Harmful soil alterations and contaminated sites are not known to the municipality
[*]Drainage is done via a rainwater sewer into a retention system
[*]Groundwater is expected throughout the entire area, which is why waterproof basements are recommended


We now naturally have several questions, among others:


[*]Are the properties listed above in any way cause for concern, or merely hard-to-understand "officialese"?
[*]Is the listing of the possible geogenic contaminants a standard clause to legally protect the municipality from liability claims in advance, or is this a special case?
[*]To what extent can the properties mentioned above affect our building project?
[LIST]
[*]Higher costs for excavation and removal/disposal?
[*]Higher costs for waterproof basement?
[*]Does other soil need to be brought in for more stable building ground?


[*]We had calculated the costs for the basement at about €60,000. Is this roughly correct considering the circumstances listed above?

Since the notary appointment is scheduled quite soon (in about 7 days), we have not yet commissioned our own soil survey. Should we definitely commission this before the purchase and postpone the appointment with the notary? The survey will be needed anyway (whether before or after the purchase) for further planning of the house. Does the municipality have to approve this since the plot is not yet in our possession?

Thank you in advance and best regards

The costs for the basement are currently difficult to estimate due to the unknown dimensions of your construction project (size, equipment?). The same applies to the associated incidental construction costs. If things go badly, they might even double the basement price. If the municipality already announces difficult soil conditions, I would be cautious about buying the property without my own soil survey if the construction budget is limited. For a quick first impression, you can also ask the neighboring existing building owners.

Own expert report, without it I would not buy it.

If you are unlucky, the entire excavation has to be disposed of as hazardous waste and you will receive restrictions during construction.

You can immediately find a pdf about it on the internet.

Own expert opinion, without it I wouldn’t buy it. If you’re unlucky, the entire excavation has to be disposed of as hazardous waste and you will get restrictions on the construction. You can immediately find a pdf about it on the internet

PDF on the internet: Yes, regarding geogenic contamination, but not regarding other conditions as building ground. Thanks nonetheless for the hint.

The costs for the basement were estimated at about €60,000. Considering the circumstances listed above, is that approximately correct?

I just rolled the dice and got a price of €137,479.63. On the second roll, it was only €58,568.55. And now the price shot up to €161,118.01. How are we supposed to know what the basement will cost? We don’t know the conditions of your property, nor the size of the basement, nor its features. Get an appraisal before buying, then you will be sure. If a few tens of thousands of euros don’t matter, just buy the property as is.

You mean 60k€ for the basement excavation, yes, that can be possible if your landfills are full. It can but doesn't have to be! But 60k€ for a basement, finished? Including excavation, landfill, and finished? Never.