Insulate the stairwell wall in the attic?

Oh, that's how it is. I thought it would be dowelled like external thermal insulation. I think all manufacturers or pure EPS variants with an aluminum side are suitable then?

I thought it would be fixed with dowels like external thermal insulation composite systems.

It is also glued. Dowels are used to be on the safe side - heavy plaster and wind suction.

I think all manufacturers or pure EPS variants with one aluminum side are suitable?

You can use anything. PUR is much better than EPS. Aluminum laminated is better than without. PUR is also more expensive (if there is enough space, then properly thick EPS as well).

Ah, I see. I need to calculate that in terms of price. Thank you very much!

Now I found a few suitable products.
I have noticed that the PUR/PIR insulation boards also come with aluminum foil facing on both sides.

What is better?
I am also still unsure how I should pre-treat the painted wall and whether to use foam adhesive or dry mortar.

My biggest concern is still that mold forms between the wall and the boards.

Now I’ve found a few suitable products. I have noticed that PUR/PIR insulation boards are also available with aluminum foil facing on both sides. What is better? I am still unsure how to pretreat the painted wall and whether to use foam adhesive or bagged material. My biggest concern is still that mold will form between the wall and the boards.

1. Aluminum foil facing (is actually always double-sided) is better than without but more expensive ==> you can calculate yourself with ubakus how "good" a particular insulation is at different thicknesses 2. Pretreat? Not at all. 3. Adhesive? As you like. Bagged material compared to a can of PU foam adhesive is like digging a pool with a shovel instead of an excavator (foam adhesive). 4. If you insulate on the cold side, no mold can form. That’s physics. That’s why houses are insulated from the outside 98% of the time (the remaining 2% are cases where exterior insulation is not possible or for other reasons). Concerns = 0

1. Aluminum-coated (actually almost always on both sides) is better than without but more expensive
==> you can calculate yourself with ubakus how "good" a respective insulation is at different thicknesses
2. Pretreatment? None at all.
3. Adhesive? Up to you. Bulk goods are comparable to excavating a pool with a shovel instead of an excavator (foam adhesive) compared to a can of PU foam adhesive.
4. If you insulate on the cold side, mold cannot form. That is physics. That is why houses are insulated from the outside in 98% of cases (the remaining 2% are cases where external insulation is not possible or other reasons apply). Concerns = 0

Interesting. I was unsure whether the aluminum coating would hold. But I happened to find a video where it was done exactly like that.

In the meantime, I have started with the ceiling insulation of the stairwell. Unfortunately, very hard-to-reach spots at the end towards the gable wall. I mounted this adhesive tape from a well-known manufacturer. A bit problematic and not sufficient due to the untreated bricks which I had previously freed from plaster residues. Luckily, there is still the adhesive compound from the cartridge tube that seals all gaps.

The actual question here is how far the PUR boards should protrude. On one side the bricks are higher than on the other. I have left the vapor barrier overlapping the hollow chambers of the bricks for now (on the side where the bricks are almost flush with the ceiling).

Is it allowed for the insulation without vapor barrier to go over the hollow chambers of the bricks up to the PUR board, or should/is it allowed that no insulation is placed over the bricks (i.e., between the PUR board and the ceiling)?