Temporary partition wall for semi-detached house, need support

The standard would actually be a building expansion joint, 2 cm mineral fiber insulation board according to DIN 18, and then usually the next neighboring house wall.

A colleague installed vacuum insulation panels on the exterior wall in such a case; they only add 2 cm in thickness and have an insulation effect equivalent to 16 cm of styrofoam.

In addition, there is a thin plaster layer, and up to the measured boundary there are another two centimeters for mineral sound insulation, which would only be installed when the neighboring building is constructed. Overall, the advantage is that the building itself is fully insulated from the start and even if the neighboring building is constructed offset, no thermal bridges can occur, and including the plaster it requires only about 4 cm in depth compared to almost 20 cm with conventional ETICS. The disadvantage is the panels, which cost about 80 euros/m2 at purchase.

And one is independent of whether, how, or when the neighbor will build.

What do you think about no insulation? Instead, coating the [Kalksandstein] exterior wall with mesh and reinforcing adhesive, maybe also a coat of paint... we definitely do not want to insulate for at most 2 years...