Interpretation of soil investigation for construction

11ant is right. The plot is sold without a house and can then be built on according to free choice. Since the plot is quite reasonably priced compared to similar plots, we are suspicious and want to be sure not to buy a pig in a poke here.

I thank you already for the assessment. What I take from it: not an unusual soil for southern Germany that can be built on with certain special measures.
How should I imagine the mentioned overflow facility during heavy rain, which is referred to in the expert report?

So, foundation slab... let's keep it simple. The fillings up to 1 m should be removed. Geogrid in and fill up with frost protection 00/32 or 00/45. MIN. 50 cm overlap and then slope off at 45 degrees. At the NHN height, that should be sufficient for frost protection. But that should also be stated in the expert report.

Seal foundation slab according to DIN 18533 W1.1-E (ground moisture).

Drain the roof surfaces into the sewer, you won't get around that.

You can assume bedding module about 15 MN/m³.

So, have to put the kids to bed now, think about what else is important. But that would be my recommendation.

Thanks. Can you estimate what additional costs arise compared to a standard foundation slab? Usually, costs of 300€ per sqm are calculated.

What exactly do you mean by drainage of the roof surfaces? Isn't it always necessary to drain into a sewer?

Usually this is regulated by the development plan, but often one is not forced to connect. That is what the section on infiltration is about. The aim is that, if the soil permits, to keep the stormwater on the property and let it infiltrate there. This is regulated by DWA A 138. Your soil usually does not allow this, or incredibly large infiltration systems are required along with additional protective measures for heavy rainfall events. Therefore, bite the bullet and pay forever for the stormwater and into the sewer. How expensive the slab will be, I unfortunately cannot tell you, it depends on many factors (material costs, steel price, etc.) but as long as they don’t want to sell you a waterproof slab, it should be possible. Regards

I take from this: for southern Germany not an unusual soil that can be built on with certain special measures.

Exactly that. And as said... there are many ways to solve the problem, all with their advantages and disadvantages.

How am I supposed to imagine the mentioned overflow device in heavy rain, which is mentioned in the expert report?

Sometimes development plans require you to infiltrate rainwater on the property. This infiltration system would then have to have an overflow to the sewer, since in heavy or prolonged rain the soakaway quickly fills up. In areas with a lot of clay, however, this is usually not required, as it is completely pointless and even potentially dangerous if you start to liquefy larger amounts of clay on the property. Infiltration under the pavement is usually required (also not really sensible) just by making the gravel layer more generous.

Since the plot is priced quite cheaply compared to similar plots, we are suspicious and want to be sure we are not buying a pig in a poke here.

The markets for building plots and developer projects behave like communicating vessels, so turbulences (such as those caused by the current uncertainty) always affect both parts. Plots like this one (for only two single-family houses or a semi-detached house and not yet started construction) are the natural first candidates for rejection. Tied-up liquidity without corresponding return expectations must be resolved "time before money." You don’t sell below cost price, but you don’t have to go above it either – the main thing is that the asset is quickly turned liquid again. "Next door" ...

And now it gets even worse: Traumhaus has filed for insolvency.

... you can currently read an excerpt of the mood. A pig in a poke remains a building plot always, here only three lottery numbers ... uh, drill cores were drawn. At least all of them come from the plot in question itself, and not just from the building area in cumolo.

How should I imagine the mentioned overflow device during heavy rain, which is referred to in the report?

Basically like a buffer tank that takes the rainwater from the property. The benefit for the sewer is to smooth out the peak load; and for the soil of the property, that the rain does not "mix" with it. Because water only knows two strong urges: flight in the direction of gravity or reaction. It always takes whichever it can get faster. The less permeable the soil is, the clearer the course is set toward reaction. Humus, which belongs to the water for this dance, becomes unfaithful to its humus family - and the softening is complete (on a slope: its slide).

Hello,

quick info: the property has been sold (not to us ...) and only the notary appointment is pending. So I assume that the matter has been settled.

Thanks anyway for your feedback.

Best regards