Sell the property completely or partial sale with investment?

In any case, this wall is very simply beautiful. There are just the bricks. Nothing more.

Exactly that I would not accept uncritically. The wall thickness is unusual even for the presumed time of construction; I could imagine a concrete core in a broader sense. But that would need to be clarified. From what you have described so far, one would probably have to call the advisor more a "guesser," or at best a "brainstorming companion." I have not yet recognized anything here to suggest that an advisor should know significantly more than those being advised. Where did your relatives meet him?

The probability that they are solid bricks throughout is very high, since it used to be a brickworks. So if they had anything, it was bricks. But I can ask again. You can definitely find that out.

Mr. X was recommended to us by a construction company with whom we have regularly carried out construction projects for years. I have not met him yet and he hasn't invested much time in the idea either. After all, he hasn't seen any money or even been offered any yet. So maybe we shouldn't expect too much now. First of all, he only has contact with the building authority - at least that's something. In DD you would otherwise have to queue at the back of a long line. That hasn't changed from before.

What came first - the brick or the brickworks

So I looked up an example calculation for the U-value online. Estimated initial values from tables and experience: 2cm interior plaster, lambda 0.7 60cm brick wall, lambda 0.24 2.5cm exterior plaster, lambda 0.7 (simplified) Resistances Rsi: 0.13, Rse: 0.04 If I haven't miscalculated, I would arrive at a U-value of the wall of 0.366. This value could still be improved by applying an insulating plaster on the outside with significantly better values. Since the roof, ceilings, and windows would all be new and thus correspond to the current standard, how do you assess this value? Is it rather poor now? Or sufficient? Is there a table or a text somewhere where you can look this up?

Ok, found it myself. Required U-value is 0.24. There would actually need to be an additional 10cm of insulation. That somehow makes the thing absurd. That would then be 70s walls...

Even during the time in question, no one was recklessly wasting bricks by the dozen just because they had access to the source. The wall thicknesses rather indicate large ceiling spans; to merely support the exterior walls of the floors above, they would be, first, considerably slimmer and, second, tapering off towards the top.

I haven't met him yet and he hasn't invested much time in the idea so far. After all, he hasn't seen any money yet or even been offered any. So maybe one shouldn't expect too much right now.

Therefore, to remain credible, he should not say anything other than "nothing is known for sure," "when the rooster crows on the dungheap..." or "more details only after the autopsy."

For any speculation about how much insulation will go on which side, it seems to me significantly too early. The same applies to new ceilings or the like (which, however, in my opinion economically already question a fundamental preservation).

At the moment, three things are important: 1) knowing where you want to go; 2) achieving internal agreement on who speaks; 3) not arousing the interest of a monument conservator.