Single-family house without a basement - generate parking space elsewhere

The most important thing for us, however, is that it works very well and is significantly more usable than the Kaltdschspeicher.

That's why there's also a vapor barrier on the attic side in the upper floor.

That’s clear, even if you probably mean "vapor retarder." The moisture transport is reduced but not prevented by it. Do you know how the vapor retarder from the attic is connected to the one in the ceiling below?

We also store all sorts of things in our attic; who wants to give away 54 sqm? If I were you, I would at least monitor the humidity over a longer period. A hygrometer with max-value memory for 12 euros from Amazon is sufficient.

That is clear, even if you probably mean "vapor retarder." The

The one in the attic is a vapor barrier according to the building specification. I assume the architect knows what he is writing. The one in the upper floor ceiling looks pretty much the same.

Do you know how the vapor retarder from the attic is connected to the one in the intermediate ceiling?

No.

If I were you, I would at least monitor the moisture over a longer period. A hygrometer with max value memory for 12 euros from Amazon is sufficient.

The house has been standing since 1997. I just put up my hygrometer. In the attic I have 37%, in the living room 34%.

At the moment, the cover of the [sät-Stange] is a bit loose. At least there is a small puddle there when it rains under the rod. That is our only problem spot with the attic.

Unventilated, unheated attic on insulated ceiling floor works even without permanent ventilation. As always, it helps to use your brain. If it is -5 degrees outside, someone has just showered upstairs and you then open the attic ladder, you of course get a lot of moist warm air going up. If you ventilate well downstairs beforehand, what should still come up? If necessary, you can also ventilate the attic again if there are windows inside. Since the temperature differences between inside and outside in the attic are smaller than in the rest of the house, this also reduces the risk of mold. Condensation moisture has less chance. But you have to be careful not to bring too much moisture up! If I were to rent out my house, I wouldn't insulate it. I don't know if you can find smart tenants. For own use in my opinion, it is okay.

Ventilate thoroughly at the bottom first, what else should then come up?

You simply can't ventilate enough for your bathroom air to become so dry that it wouldn't condense at -5 degrees. That's just physics.

If you shock ventilate at -5, the air has hardly any moisture left after ventilation.