Cost planning - core renovation of farmhouse / country house

Building from 1928, wooden beam ceiling.

... and with a mansard roof, and a semicircular "bay window," wonderful.

You have received cost estimates on well over 25 pages in this thread.
And no, you will not get 200 sqm renovated to the level you want for 200,000. We have sunk almost 160,000 euros into a 100 sqm little house by now with a lot of our own work. Without frills like ventilation and KNX.

I have received lectures in this thread over more than 25 pages on why you simply cannot buy a farm estate in Lower Saxony. Cost estimates, not so many though. I read through it again until page 12, and there were not many numbers there.

... and with a mansard roof, and a semi-circular "bay window," wonderful.

Visually, yes. I gather from your sarcasm (?) that these are more elaborate to renovate than others.

You need an architect with experience in the field of old building renovation, a structural engineer with experience in old buildings - both are rare specimens and almost always expensive. Gutting costs money, you always have to plan at least a 20% buffer for nasty surprises that come with old buildings. That's how it is. You need companies that can work with old buildings, where right angles are rather rare. You often need custom-made parts, which cost extra. You always have to expect delays.
For the size, just the mandatory energy refurbishment of the building envelope will cost 50,000 without your own work.
A mansard roof of that size newly built will also be in that range, probably more. Presumably, the floors on the ground floor are at most a rammed screed; if the house still has no heating, no one will have installed new floors with drainage... so excavation inside the building.
And as sensitive to noise as you are, you won't be happy with impact noise in such houses. 200 sqm of new floors, you'll quickly be in the five-figure range.
With your standards for comfort, you should rather calculate in the direction of > 500,000.

You need an architect with experience in the field of old building renovation, a structural engineer with experience in old buildings – both are rare specimens and almost always expensive. Stripping out costs money, you always have to plan at least a 20% buffer for nasty surprises that come with old buildings. That's how it is. You need companies that can work with old buildings, where right angles are rather rare. You often need custom-made parts, which cost extra. You always have to expect delays. For a building of that size, the legally required energy-efficient renovation of the building envelope alone will cost 50,000 without any personal contribution.

Thank you very much for the assessment, that was very helpful. I am considering buying this book about renovation from Stiftung Warentest. Has anyone read it, is it recommended for a rough, first overview?

Thank you very much for the assessment, that was very helpful. I am considering buying this book about renovation from Stiftung Warentest. Has anyone read it, is it recommended for a rough, first overview?

I know it. It's more of a nice overview. It would be more sensible to inspect the property with an architect specialized in old building renovation.

Visually, yes. I gather from your sarcasm (?) that these are more complex to renovate than others.

No, no sarcasm. I always have to cry when philistines in municipal councils recklessly misuse something essentially innocent in their eyes, like a eaves height restriction, to exterminate the architectural heritage of the mansard roof. The bureaucracy of the German Michael will still choke on its reduction of diversity to a maximum of four and a half different apple varieties. With gables, it’s no problem for the person willing to renovate, and hipped roofs are always somewhat more complex – but then also as a saddle roof.

You need companies who can work with old buildings, where right angles are rather rare.

I don’t see any little witch’s castle of the Counts of Crooked and Slanted here.

I’m thinking of buying this book on renovation from Stiftung Warentest.

I don’t know it, but I expect only mediocre expertise from them, more like a tabloid-style special issue – with clichés about mold cultivation with insulation stuff, more like a pharmacy magazine, if you know what I mean.