Exterior wall for KFW 40 (+) with or without ETICS?

The developer acts more or less as the site manager... a company in the city is being sought here to then build the house...

Ultimately, it should not be too noisy and should be well insulated... and of course not a 20,000 euro surcharge.. I just want to make the best choice for the next few years and then leave my daughters a relatively good house :)

When the ETICS facade is due for replacement in 50 years, you tear it down and renew it with the then contemporary and sensible insulation material.
What do you do in such a case with the monolithic wall? Add another layer. Have fun in the castle.

What else should I significantly improve in a KfW40 house? A little more and you have passive house standard. And after that, energy demand approaches zero and nothing. You also have to see where the energy standards come from; a solid construction from 1970 often has about 300 kWh/sqm, a 40 house is below 25 kWh/sqm. In 50 years, definitely nothing will be added to that. That would be insulation madness to the power of 10.
Regarding wall thicknesses... we come to 40 cm stones (plus plaster). A prefabricated house of the type that only consists of insulation mats between wooden beams and a board on each side results in about 40 including plaster. The OP’s example with ETICS with 24+18=42 comes out the same. It’s all about the same.

EPS is the insulation material of the present and foreseeable near future. Anyone who likes statistics can gladly google.

Styrofoam is at the top of the statistics and will probably continue to lead there. ETICS is often the only option in renovations, and Styrofoam is always the cheapest. Still, one does not have to consider that the future.

Where is your problem? I have my opinion. It was asked! And I try to avoid plastic as much as possible, yes.
7 years ago, when I built, I didn’t have much time and inclination to X-ray every building block of the house. I probably would have still built with ETICS back then. But I have been living here for 7 years, could have afforded financially “more house” in hindsight, and so I say again: not again!

I also think it’s great that you tell me how to attach my things to my facade. The stuff is already hanging.

I find it more likeable... my next house will be monolithic. Then I will also have nice thick window sills inside. Also such a disadvantage.

An exchange of arguments leads to discussion. That is what a forum is normally for.
And I’m not telling "you" how to attach things, but everyone. Because "nails don’t hold well in ETICS" is undoubtedly a true statement, but I propose the thesis that nails are always bad, in wood barely ok, especially on facades.
By the way, chewing gum holds poorly on glass.

Aerated concrete is of course in the lead, no question. But so far, I think it hasn’t been said whether this option exists on the part of the building owner.

You should orient yourself on — forcing nobody to use material they don’t (well) know. It only causes trouble.

What would you prefer here?

Read the last 10 pages, then you can pick an opinion :D

To go from the standard 14cm ETICS to 18cm ETICS I pay 1800.

Without counting every penny twice, that still seems to be in the green zone. Besides the extra cost of the thicker insulation, for example, deeper window sills and parapet flashings are needed.

It is a massive flat roof that additionally gets insulation and then is greened... so I think that should be good against noise.

Very good. Please always use massive flat roofs and definitely not one made of wood!

What else should I significantly improve on a KfW40 house? A little more and you have passive house standard. And after that, pretty soon, energy demand of zero and nothing. You also have to see where the energy standards come from, a massive building from 1970 usually lies around 300 kWh/sqm, a 40 house is under 25 kWh/sqm. Nothing more will be added in 50 years. That would be insulation madness to the 10th power.
Regarding wall thicknesses... we come to 40 cm bricks (plus plaster). A prefab house of the type that only consists of insulation mats between wooden beams and a panel on each side comes to about 40 including plaster. The OP’s example with ETICS with 24+18=42 comes out the same. It’s all about the same.

Our ancestors thought the same 50 years ago. Energy cost nothing.
Who knows what will still change in 50 years.
17.5 cm aerated concrete + 20 cm insulation should be a suitable combo for the OP, that would be 37.5 cm for KfW 40 envelope.
I criticized the unnecessary thickness of the hollow brick, aerated concrete can do better. But still the elephant rule above applies.

The developer more or less acts as the construction manager... a company is being sought here in the city that will then brick the house...

So far, I thought that by "developer" you meant, in the typical layman’s conceptual confusion, the general contractor (the construction company to which you want to give the entire construction execution as a contract). Apparently, your tangle of terms is even more confused – so explain whom you mean each time. If I interpret it correctly now, do you mean a mailbox general contractor???

and then leave a relatively good house to the daughters

Today, I would no longer "build" on the assumption that the children will later form a civil partnership in the place of the parental home.

I criticized the unnecessary thickness of the hollow brick, KS does that better.

What can sand-lime brick do better: be thick? – On the contrary, or did you mean exactly that: KS can carry more slimly and leave more total wall thickness for the ETICS?

But nevertheless, the elephant rule applies as mentioned above.

The 11-antenna rule (stone mantra) unfortunately has no clause for the case* that you take a mailbox general contractor who already bungles the bricklaying: because the mason is only executing, the GC does the “planning” (as long as one is content with a draftsman’s house – but I also consider that a misinterpretation of “you build the first house for an enemy” *LOL*). *) I warmly thank you for the note regarding this small bug in my mantra :-)

Exactly, so it is a company that distributes the tasks but takes care of everything, planning, statics, etc. (just like an architect).

Yes, the thing with the daughters may be true, but they should have the option or inherit a quality house that they can then sell well.

The company has an excellent reputation.. I have spoken with some and also know some personally :)

Exactly, so it is a company that distributes the tasks but takes care of everything, planning, statics, etc. (just like an architect).

So an architect who prefers to earn his money as a mailbox general contractor?

The company has an excellent reputation.

At this point, the Kölsche inevitably brings up the sentence about the expensive wools: dat kaschmir nit vüürstelle. How is that supposed to work if you have changing structural shell builders?

Yes, that with the daughters may be true, but they should have the option.

What I meant to say is: inheriting houses is a thing of the past. Whoever builds a house well under sixty today will in most cases "pass it on with a warm hand" again.