Floor plan tube house L-shape triangular plot including oak tree

There is only exactly one light gray.

Exactly. Pussi recommends a fresh stone gray, if I remember correctly.

Does it have to be plaster? There are also facade panels, and I find that very interesting as an accent and as a deliberate "counterpoint" to the plaster. Then the problem of crack formation (which I am hearing about for the first time, by the way) should not occur.

Here is another thread dealing with stain problems on dark plaster. (in case the gray is intended to be towards anthracite)

Is it mouse gray or rather stone gray?

The painter should say something about the color tone (regarding the "darkness").

There is a light reference value that - depending on the masonry or insulation - must not exceed (or fall below? I don't remember) certain values.
We also have quite dark exterior colors and a monolithic wall structure. In general, darker colors can be chosen there. With insulation, our painter would not have done that because it can quickly lead to cracking and thus problems.

But the painter should know that!

Yes, of course he knows that. The color shown above has the HBZ 25. He doesn't want to go darker. If I understood that correctly, it would work with our single-layer construction method using insulation plaster. In that respect, I don't understand his caution...