Construction costs are currently skyrocketing

From a reliable source, in the end 4.3 million flowed. The land was already developed (in the middle of the village) – outdoor facilities are minimal and the ancillary costs are not spread over the usual 150 m2 here but over 1200, so they should proportionally weigh significantly less per m2 than for the users here. And as already mentioned, without land costs.

In such a measure, it can already be 75% construction costs and 25% other costs (as I wrote). In this respect, you might end up somewhere around 2,700€/sqm pure construction costs.

Thanks. But will this calculation also be fulfilled upon handover? And where do you see the differences regarding the mentioned projects? Where exactly are those 800 euros or 1 million sum hidden, where were they spent?

Unfortunately, my crystal ball says nothing about that. At least regarding the second part of your question. But there are many ways money can leak – own project costs, fees, planners, interim financing costs, changing planners during the process (can really hurt in technical building equipment) etc. It may also be because laypeople dealt with a business area – residential construction – of which they had exactly zero knowledge and paid their dues. For the first part, I can report from recent years that maybe 1-3% of our clients had significant cost overruns. Yesterday I saw an inquiry where there was (for a purchase) an arrangement fee, a broker providing evidence, and a closing broker. About 17% ancillary costs were added on top of the purchase price... Current cases: Quarter in Düsseldorf (besides social housing there are also offices) construction costs 2,650€/sqm Developer in Berlin (higher priced) construction costs 2,500€/sqm Ruhr area construction costs (privately financed) 1,800€/sqm (client has own construction company and makes no money with it) Leverkusen construction costs (private and subsidized) 2,700€/sqm Duisburg (private and subsidized) construction costs 2,800€/sqm All cases together from professionals (project volume half a billion €), who are not immune to price increases but have sufficient experience to calculate reasonably well. Even if another 10% were added to construction costs, we would still be far away from your 3,500€/sqm.

Now I had to check what ETWs cost in our district town.
Built in '66, 6th floor, not appealing from the outside, no pictures available from the inside. Allegedly renovated a few years ago, 2570 euros/sqm with garage parking space.
New building, occupancy 2023, about 4500 euros/sqm.

Pretty intense when you consider there's no metropolitan area far and wide.

Apartment building construction is ALWAYS more expensive than single-family houses (excluding land)...

Hm, apartment building construction is actually not more expensive but very efficient per m3 of space. Just the resulting synergies alone. A thick, sophisticated heating system supplies 50 residential units. With 2 exterior surfaces, each apartment then only needs 1kw heating load and that's it.

After the interest rates only rose in 2022!!!, there was finally a decline yesterday o_O

I found out today that some plots in our construction area have already been returned (reservation canceled)... Whether due to the construction prices or the [Nahwärmezwang], I do not know unfortunately...

After interest rates only rose in 2022!!!, there was finally a decline yesterday o_O

Calling a sideways movement a decline is "bold" (seen too optimistically). Even when interest rates were in free fall, there were phases where they stagnated or declined slightly. We'll only be truly wiser at the end of the year.