Attic problem. High humidity - Controlled residential ventilation?

So we have the foil between the attic and the ceiling.

I still don’t understand:
Question: Do you have a vapor barrier (barrier - not just a retarder) on or in the floor between the living space and the attic?

In other words, is there a plastic sheet on the attic floor or not?

If there isn’t one, you have to insulate the attic and heat it completely.

Regards,
Andreas

Since it was built solidly, I assume that there is a reinforced concrete ceiling between the upper floor and the attic. Normally, you don’t need an additional vapor barrier in between here. I thought it was like a vapor barrier. You can also just lay the insulation directly on the floor in the attic, since normally no moisture should come from below... Or am I mistaken somewhere?

But on the topic: You should describe the structure very precisely, both of the roof and of the ceiling between the upper floor and the attic.

Regards Specki

Hi,

there is a reinforced concrete ceiling between the upper floor and the attic. Normally, you don’t need an extra vapor barrier in between. I thought it functions like a vapor barrier.
You can also lay the insulation directly on the attic floor, since normally no moisture should come from below…
Or am I mistaken somewhere?

Yes, you are mistaken. A reinforced concrete ceiling is not vapor-tight and you definitely need an extra vapor barrier. Otherwise, all the moisture from the concrete ceiling will go up into the attic.
In our old house (fortunately only rented) this exact vapor barrier was missing. The attic was very damp for the first few years, and things even got moldy there. It got better later, but never good.
According to our neighbor (project manager at a very, very large construction company), this is a clear defect that they themselves have also experienced. The result was that they had to renovate the roofs in an entire settlement for the US Army.
This vapor barrier is apparently often "forgotten".

It doesn’t have to be the reason in the case of the OP, but it could be.

Best regards,

Andreas

we have a knee wall. Below we only have a concrete ceiling. Upstairs we expanded the 2nd floor with drywall. In the picture you see the 2nd floor and the attic. The wooden beams were insulated from the 2nd floor up into the roof and sealed with foil. The 2nd floor also has foil for the ceiling between the attic. In other words, when I stand in the attic I see the insulation wool. On top of the insulation wool we laid chipboard panels. In other words: all wooden beams, both above and below, were insulated and sealed with foil.

So. And now it is cold and not ventilated upstairs. In the living area, you have a high vapor pressure. The moisture is slowly but steadily transported into the roof attic. In winter, the humidity there will eventually reach 100%. Ergo: you urgently need a well-functioning ventilation. The insulation in the roof attic is then, of course, pointless.

So. And now it is cold and unventilated upstairs. In the living area, you have a high vapor pressure. The moisture is slowly but steadily transported into the attic space. Here, the humidity will eventually rise to 100% in winter. Ergo: You urgently need good ventilation. The insulation in the attic is then, of course, pointless.

And what if I leave the windows upstairs permanently on tilt?