Garage construction made of concrete! 3 walls or house extension? What do you think?

Something seems to have settled in your head. Like "thicker = more massive". Materials also evolve.

No, not at all. I didn’t mean "thicker = more massive" but "solid = indestructible", see post #6, which I referred to:

A prefab house is not a concrete bunker.
If you crash into it with a car, you’ll probably end up in the living room. You can get through the walls with a decent hammer.

That’s exactly what I referred to and responded to. Maybe someone still has some leftover Poroton T8 36.5cm and Styrodur and can whack it with a "decent hammer" (20 kg sledgehammer?) ... and then post a picture of the result. I already have an idea how it might look...

That results in crumbs twice. But also hit [Kalksandstein]. The Styrofoam has no load-bearing property; the [Strin] behind it is responsible for that.

We live in massive and monolithic construction. Ytong, plaster, paint, that's it. Advantages: If there's water damage, it's not such a total disaster like in timber frame construction. Now in summer, the house is nicely cool. Good fire protection. Karsten