Full rafter insulation roof or insulation on concrete slab

The keyword fire hazard would then also be an argument against the cold storage floor, and the probability of cracking increases with every material change, so certainly also e.g. with aerated concrete interior walls in the brick house. This partly reminds me of this discussion:

The keyword fire hazard would then also be an argument against the temperature-variable storage floor, and the probability of cracks increases with every change of material, so certainly also e.g. with KS interior walls in a brick house. This partly reminds me of this discussion:

A wooden construction is generally cheaper than a concrete ceiling.

However, we get the concrete ceiling at the same price – so basically I don't have any disadvantage from that, right?

However, we get the concrete ceiling at the same price – so basically, I don’t have any disadvantage from that, right?

Conversely: for your general contractor, it is probably more practical to have a 50/50 mix of this and that, and he prefers to pass on his mixed calculation to you rather than always calculate both variants in detail. That you then also need load-bearing walls on the upper floor is basically not a disadvantage – except if they are in a particularly unfavorable way "incongruent" to those of the ground floor and then possibly require lintels or more reinforcement there. Builders worry about every little detail – but contractors "have to" think in cubic meter scales, otherwise their business doesn’t add up. More steel or more concrete are cheaper than more working hours for a five-decimal-place calculation, which only really excel-obsessed builders (and the big names among the solid construction licensors) can afford. For the regional contractor, this is therefore no cause for concern if he simply calls the same price for both variants for the sake of simplicity. In his operational process, this is practically just like a different color.

Insulation on the concrete ceiling and thus no full rafter insulation - here is the response from my general contractor on this topic:

But to be honest, I'm not so enthusiastic about it. The stage area then becomes a cold zone. This is then only limitedly usable as storage space. If somewhat warmer air enters the attic through the ceiling opening in winter and meets the cold air on the underside of the roof, then there will be condensation at this spot.

What do you think? Is he right?

I don't recall if he addressed that in his main thread, but has insulated his attic afterwards.

He is right. It is exactly what he says that prompted us to insulate the floor afterwards with [Klemmfilz] and [Climafolie]. Now it is okay. A tempered room, frost-free in winter, reasonably cool in summer.