Uncertainties regarding size, planning itself is so far completed

In your calculation example, I am missing some items that a proper businessman must consider; after all, he wants to be able to operate on the market for many years

What is missing then? I deliberately left out the interior walls because I thought they only cover minimal areas and, on the other hand, no sloped walls need to be bricked up, i.e., the unit price per m2 is probably lower (a construction company told me this; they do look at the floor plan and the difficulty, and sloped walls instead of straight walls would raise the unit price somewhat). Apart from the interior walls, what else is missing? Do sums add up in the end, or is it not rather the case that for a comparatively small amount of money compared to the overall project (including land, often certainly 400,000 EUR and more) one gets a great benefit?

Hello,

What is missing?

You, as a business economist, should know that there is a difference in price calculation between pure merchandise trading and manufacturing industry. Your cost accounting is set far too low. It must include material purchase, production, and profit; possibly discounts/cash discounts. Aside from the fact that these costs vary nationwide.

Example: I just had the contract documents of a renowned provider from NRW on my desk for review. For 11.80 x 11.80 m and single-story construction, DN 38°, widening the house by 0.20 m to 12.00 m costs €11,400.00.

... or isn’t it actually the case that for an amount of money that is small compared to the overall project (including land, certainly often 400,000 EUR and more), you get a great benefit?

In my opinion, you are under the mistaken assumption that _your_ taste applies to all builders. Not every builder likes straight walls, not everyone likes slants. Therefore, it is pointless to write about taste and thus about supposed added values; that means something different to every person.

Rhenish regards

I personally also feel more comfortable in the bedroom with sloping ceilings

Terrible, then skylights so it definitely patters in the room when it rains.
And always problems with darkening. No no

True, roller shutters hadn't been invented yet - dormers neither

Terrible, then also skylights so that it really patters in the room when it rains.
And always problems with darkening. No no

Actually, I have neither rain pattering nor problems with darkening.
No no.
That is really a matter of taste, not a "matter of fact."

I like the sound of rain - it is very calming.