Insulating unheated attic - electrical installations

Hello,

we are building new and have an attic with limited accessibility. The plan is on the one hand to create a storage room, and on the other hand to set up a play area for children (there are windows).

The attic is unheated. The collar beams have insulation with PE foil (I am currently considering switching to a climate membrane at short notice). OSB boards will be laid on the collar beams.

I have had an offer made to insulate the attic on the roof slopes as well, I am still waiting for the offer. However, I am also considering doing this myself.

After some research, I believe the procedure would be as follows: - Insulation between rafters with mineral wool, with about 4cm space to the outside towards the breather membranes - Attach a PE foil (or climate membrane) on the insulation between rafters - observe the tightness and fastening instructions - only glue or if stapling, use additional sealing tapes underneath where stapled - overlap two foils by about 10cm - tape transitions to gable/wall and if necessary seal with a special adhesive (visually similar to silicone) - install counter battens (counter battens perpendicular to the rafters) - by firmly screwing, the foil is pressed tight enough so that it remains sealed despite the hole from the screw - alternatively additionally tape in the screw area between rafters and counter batten - electrical installation only between the counter battens and only break through the drywall, never damage the PE foil in the process - drywall on the counter battens

Is that correct and proper especially regarding the electrical installation if the PE layer is never penetrated?

Regarding the rest of the procedure, I want to consult again with the architect to be sure I am not doing anything wrong.

Thank you very much for your information.

That sounds quite confusing and a lot doesn't fit together... 1. Problem: Windows in the unheated attic are certainly not thermal insulation windows, or are they? 2. The vapor barrier in the upper floor must seamlessly continue into the attic. If you have already insulated and clad the upper floor, you would have to tear everything open again. Furthermore, why do you want to leave a 4 cm gap there? Your whole concern about gluing, screwing, and stapling is not correct that way. How was it plastered above? Leaks inevitably occur there... Etc. Etc.

Hello, thank you for your answers.
Unfortunately, you did not comment on the question about the electrical installation.

Nevertheless, your objections are of course interesting.

1.Problem: Fenster im unbeheizten Dachboden sind sicher keine Wärmeschutzfenster oder doch?

Yes, completely normal like in the rest of the house

Die Dampfbremse im OG muss nahtlos in den Spitzboden übergehen. Hast du das OG schon gedämmt und verkleidet müsstest du das alles wieder aufreißen.

The builder is doing that, not me
The whole thing is considered separately from the attic, insulating the attic is an additional retrofit
Why does it have to transition seamlessly? Is the concern that moisture can escape through the OSB layer/insulation layer under the OSB?

warum willst du da 4 cm Abstand lassen?

So that the insulation is ventilated towards the vapor barrier in case water (drops)/moisture still penetrates from outside

Deine ganze verkleben verschrauben und vertakern Sorgen sind so nicht richtig.

Explanation? When I research this, I read everywhere that under no circumstances may even a tiny hole form in the vapor barrier film, e.g. because otherwise the warmer and humid air has a positive pressure due to the heat and is forced through this hole, forming condensate there.
This was explained to me even by an advisor from the material market.

Wie wurde oben verputzt?

Not at all yet, why is that relevant?

Da entstehen zwangsläufig undichtigkeiten... Usw. Usw.

Explanation? Does plastering cause leaks? The architect explained to me that it is precisely the plastering that ensures the airtightness of the house. Which makes sense because the bricks are not built airtight.

Thanks for further answers.

Staples are not a problem, it no longer needs to be sealed.

What kind of [Unterspannbahn] do you have in the roof? It is always important that it becomes increasingly impermeable from "outside to inside."

You can then save yourself the 4 cm gap.

Otherwise, I think you have done quite good research.

I would recommend a vapor barrier, it does not even have to be a climate membrane.

In almost all building descriptions I have had in my hands so far, the attic was mostly referred to as expansion reserve with the verbal note to insulate it later. If you are right, then I am misinformed. By "in between" I mean the "OSB layer".

The most important note is actually that you need an airtight connection between the two vapor barriers. Staples and nails are the least of the problems in comparison.