ᐅ Insulating the Stairwell Wall in the Attic?

Hello everyone,

In addition, I would like to insulate the four walls of the stairwell, which are built into the attic, attached to the ceiling of the top floor. Heat rises freely from the living space toward these walls.
The door is new and very well sealed.
The wall thickness is probably between 10cm and 15cm (4 and 6 inches).

I found several options online but have not reached a conclusion.

The thickness does not matter much to me.
Which option would be best here?
The attic itself remains unheated.

handwerk97 schrieb:

Additionally, I want to insulate the 4 walls of the stairwell that are built into the attic, along with my top floor ceiling.

I don’t fully understand the structure yet. Please take some photos from above (attic) and from below (upper floor).

As a rule of thumb, I would say you should insulate everything that is on the cold side. So, the stairwell walls above the upper floor (which are located in the attic) should be insulated on the attic side.

That's how it looks. Almost like the staircase extends into the attic. On the joist layer above, as well as on the floor structure.

But what kind of material should I attach to the walls?
I was thinking about 20cm (8 inches).

handwerk97 schrieb:

What kind of insulation material should I attach to the walls?
I was thinking about 20cm (8 inches).

Use whatever fits the space and is affordable. You can calculate the insulation effect with ubakus. I would have chosen 12cm (5 inches) of aluminum-faced PUR foam (but here in the Rhineland I can get it very cheaply).

nordanney schrieb:

Use whatever fits and is affordable. With ubakus you can calculate the insulation effect. I would have chosen 12cm (5 inches) foil-faced PUR (but here in the Rhineland it’s also available very cheaply)

Ok, thanks.
Is the material simply fixed to the painted wall with plugs, or is there something to consider here to prevent mold growth?

handwerk97 schrieb:

Ok thanks.
Is the material just fixed with plugs on the painted wall, or is there something to consider here to prevent mold growth?

EPS or PUR is simply glued on.
Since you are insulating on the cold side, mold will never occur.