ᐅ Polystyrene Insulation or Mineral Wool in Winter

We are currently building a KfW40 new construction using solid construction methods. For the exterior walls, the plan is as follows: on the inside, aerated concrete blocks, then 160mm (6.3 inches) of insulation (thermal conductivity class 032), an air gap, and finally facing brick. Our contractor usually installs mineral wool insulation. Since our house will be built over the winter, the contractor suggested using polystyrene insulation with the same properties (160mm, WLG 032) instead, to avoid moisture-related issues during the construction phase. Of course, mineral wool would not be installed in the rain and would always be covered with tarps, but here in the north the wind can sometimes tear off the tarp over a weekend, which could cause the mineral wool to get wet. In principle, the reasoning seems plausible to me, but the final decision should be ours. In terms of cost and quality, both options are comparable. I would appreciate your assessment.

Pros of mineral wool:
- Non-combustible
- Easier to dispose of
- Better heat protection in summer due to greater thermal mass (is this relevant with our wall build-up?)
- Better sound insulation (also relevant with our wall structure? It’s a rather quiet area...)

Pros of polystyrene:
- Resistant to moisture, resulting in fewer issues and potentially faster construction

Have I overlooked anything? How would you decide?