ᐅ Insulating the Stairwell Wall in the Attic?

Ah, I see.
I thought it would be fastened like external thermal insulation composite systems (ETICS).

I think all manufacturers or pure EPS variants with an aluminum facing would be suitable then?

handwerk97 schrieb:

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

It is also glued. Dowels are used just to be safe – heavy plaster and wind suction.

handwerk97 schrieb:

I think all manufacturers or pure EPS versions with an aluminum facing would be suitable?

You can use anything. PUR is much better than EPS. Aluminum facing is better than none. PUR is also more expensive (if there is enough space, then really thick EPS is also an option).

Ah, I see.
I’ll have to calculate the cost for that.

Thank you very much!

Now I have found a few suitable products.
I have noticed that there are PUR/PIR insulation boards available with aluminum foil facing on both sides.

Which is better?
I am still unsure about how to prepare the painted wall and whether to use foam adhesive or mortar in bags.

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

handwerk97 schrieb:

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

Which is better?
I’m still unsure how to prepare the painted wall beforehand and whether to use spray foam adhesive or adhesive in bags.

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

1. Aluminum foil facing (usually on both sides) is better than without, but more expensive.
==> You can calculate the "performance" of different insulation thicknesses yourself using U-values or R-values.
2. Pre-treatment? None needed.
3. Adhesive? Use whichever you prefer. Adhesive in bags is like digging a pool with a shovel compared to using a digger (spray foam adhesive).
4. If you insulate on the cold side, no mold can form. That’s basic physics. That is why about 98% of houses are insulated from the outside (the remaining 2% are cases where external insulation is not feasible or other reasons apply). Concerns = zero.

nordanney schrieb:

1. Aluminum foil facing (usually on both sides) is better than no facing but more expensive
==> You can use U-values yourself to calculate how effective each insulation thickness is
2. Pretreatment? None at all.
3. Adhesive? Up to you. Bulk adhesive 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, mold cannot develop. That’s physics. That’s why about 98% of houses (the remaining 2% are cases where exterior insulation is not possible or for other reasons) are insulated from the outside. No concerns there.

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

In the meantime, I have started insulating the ceiling of the stairwell. Unfortunately, the spots near the gable wall at the end are very hard to reach.
I installed tape from a well-known manufacturer. It’s a bit problematic and not sufficient because of the untreated bricks, which I previously cleaned of plaster residues. Luckily, the sealant from the cartridge gun fills all gaps.

The main question is how far the PUR panels should extend. On one side, the bricks are higher than on the other. For now, I have left the vapor retarder so that it overlaps the hollow chambers of the bricks (on the side where the bricks are almost flush with the ceiling).

Is it acceptable for the insulation without a vapor retarder to extend over the hollow chambers of the bricks up to the PUR panel, or should there be no insulation between the bricks and the ceiling (i.e., between the PUR panel and the ceiling)?