Demolition and redevelopment on a steep slope - assessment?

Good evening,
as a long-time silent reader, I finally have the opportunity to ask a question here for which I need advice:

We have the opportunity to purchase a plot of land in a town more or less directly south of Stuttgart.
Three parcels of land (built on with 3 houses built side by side, a total width of about 26 m) are being combined into 2 new parcels. The surveying is in progress.

Rough data (of one resulting parcel for us):

[*]approx. 500 m² with approx. 13 m width and just under 39 m length
[*]building window possible over the entire width and approx. 10 m building depth
[*]steep slope (south-southeast, approx. 10 m height difference from the "ground floor" to the lower end of the garden) with entrance at the upper end (leads directly to the town center)
[*]fantastic view into the green on the garden side, with a small local type of S-Bahn running past at the lower end
[*]old building (uninhabited, empty, 80+ years?), whose cellar/basement is completely located in the slope
[*]the slope garden corresponds to the old building and is equipped with retaining walls etc., but is of course similarly old; otherwise lawn area and a few trees.

The following sketch roughly shows the condition:


The current plan is to build the two new parcels with 2 semi-detached houses, and a southern German prefabricated house supplier (including prefab cellar) is specifically being discussed. The "cellar" is to be used only in the rear slope as a cellar and expanded in the front as a basement for living space.

My questions:

[*]How crazy is the idea? I fluctuate between a) a unique fantastic opportunity because of the great view on one side and being directly in the town on the other side, or b) a total crazy idea because all costs on this slope will explode. In 2.-3. I bring 2 examples:
[*]Currently, about €40,000 is planned in an offer for the civil engineering work (excavation, storage, removal, etc.). According to the contact person, it is so little because there is already a house and after demolition the construction pit is already there. Sounds too simple to me. Plausible?
[*]Furthermore, roughly €60,000 is budgeted for the demolition of the 3 existing houses (all 3 directly built next to each other, same condition as described above, 8-10 m building depth, cellar+ground floor+upper floor+partly attic). That also sounds little to me. Is that roughly the right magnitude?
[*]Am I overlooking (expensive or different) risks besides the earthworks, demolition, strenuous/expensive outdoor facilities, noise from the S-Bahn?

I hope I have not forgotten any important information for an initial assessment. I am happy to add more. Many thanks in advance for any advice!

Hello,

so I can only say something about demolition in the Rhein Neckar district, but we had an offer for a 150sqm single-family house with a partial basement and gutting for 65,000. We had to search for a long time to get it cheaper and are now gutting it ourselves.

However, I cannot assess whether we are really an exception here.

Best regards

If I understand correctly, a row of three terraced houses from around 1940 is to be demolished, the middle plot divided and merged with the end plots, and then a semi-detached house built - planned (and contracted) together, which is already very clever.

I hope I haven't forgotten any important information for an initial assessment.

Yes, photos.

a row of three terraced houses

Not quite. I was also imprecise there. Theoretically, the houses are detached, but the distance varies between 10 cm and 1 m depending on the house and area.

Yes, photos.

Since the matter is not finalized yet, I prefer to post photos only to a limited extent. Here is a view of the mentioned three houses from the property (and a small garden shed is also in the picture) and a close view of the left house, where you can also see the street level at the fence on top.

Hello, so I can only say something about the demolition in the Rhein Neckar district, but we had an offer for a 150 sqm single-family house with a partial basement and gutting for 65,000. We had to search a long time to get it cheaper and are now gutting it ourselves. However, I cannot assess whether we are really an exception here. Regards

Thanks for the data point. It at least makes our estimate look a bit low.

Oh, then your walls are about 20 years younger than my youngest.

Demolition
May be sufficient. The big question mark is the pollutant load. The higher it is, the more expensive the disposal.

Earthworks are cheaper than on a purely undeveloped plot
Leave the old wall on the hillside side standing, it saves you from having to secure it during the construction phase. Many advised us against it as well, in case something slips. However, we built below and not above like you.

The estimates for earthworks and demolition costs might be accurate. I would still recommend having a buffer. At the latest, the outdoor area will take its toll.

The statics can still cause a significant increase on the cost side