ᐅ Interior Insulation of Basement Wall in Stairwell – Condensation Issues

Hello everyone,

We are currently renovating the entire house, including installing extensive insulation. The basement will remain uninsulated on the outside; only the basement ceilings will be insulated.

The basement is mostly unheated.

The house has two floors plus a basement, with the stairwell being heated. Each floor and the basement have a door leading to the stairwell.

In the stairwell basement, we currently have some thermal bridges.

Wall 1 faces the ground and is not insulated yet. Wall 2 leads to the storage room, which is cool. The floor remains uninsulated as well.

The wall that runs up to the stairs faces a cold laundry room in the basement. This wall cannot be insulated because of the staircase, not even from the other side.

We would like to insulate Wall 1 and Wall 2 with minimal thickness if possible (e.g., PU/PIR). Otherwise, we plan to use mineral wool or wood fiber insulation throughout the house.

What should we consider here? Our energy advisor said this is too complicated, especially regarding condensation, and suggested consulting a building physicist (just for two walls?!).

Does insulating here make sense, and if so, how should we proceed?

Thank you very much!