ᐅ A tightly sealed, well-insulated wooden house without plastic? (Vapor barrier)

Hello Alex,
you’re right that the membrane doesn’t make a huge difference. Especially since it’s installed once and then stays inside the house for decades.
That brings up the next question: How long does such a membrane last? Does it need to be replaced every X years? That wouldn’t be ideal either.

I’m just a bit unsure about it, which is why I want to find out if it’s possible to do without it. And if so, how?

Best regards
Specki

Alex85 schrieb:
You are right about the airtightness; this is indeed one of the main drawbacks, especially when building with wood.

According to our energy consultant, who conducted the blower door test, the airtightness achieved with well-constructed timber frame buildings is almost impossible to match with solid construction.

More and more suppliers seem to be moving away from using foil, especially regional carpentry companies. In our case, the OSB board is airtight and bonded, serving as the vapor retarder. However, the OSB board also contains adhesive, which is not entirely eco-friendly. Personally, I found a fully ecological approach too extreme; I believe a compromise is necessary. We also have a timber frame house insulated with wood fiber. On the exterior, we used wood fiber insulation boards, and there is also wood fiber insulation in the installation level. However, even the wood fiber insulation is treated and not pure wood, so it’s not 100% eco-friendly in my opinion. The solid wood ceiling is glued as well.

Specki schrieb:
Because I would like to avoid plastic as much as possible.

Depending on your requirements, OSB boards can also be problematic. Would a solid brick construction be an option? In my opinion, its wall structure can also be done "without plastic" if mortar is used (no adhesive).

Specki schrieb:
But mostly because it always represents a potential problem area.

From what I understand, a separate installation wall system practically eliminates all problem areas in this regard.

Specki schrieb:
I’m not so keen on solid wood; I was more thinking about a timber frame construction with insulation.

Solid wood was just my initial rough idea. If you look at the supplier mentioned, you will see that they also build with multi-layered, insulated walls. Instead of OSB boards, they use gypsum boards.

oleda222 schrieb:
According to our energy consultant who performed the blower door test, achieving airtightness with well-constructed timber frame buildings is almost impossible for solid houses.

The focus is not on the airtightness of the entire building but on the airtightness of the membrane. Even a single improperly driven nail, as an example, can allow moisture to penetrate the insulation and reach the timber.

There are wall constructions without vapor barriers.
There are also house providers who avoid using assembly foams and instead use tested and environmentally friendly materials. Try searching for Wir-Leben-Haus.

I also believe there is an association or something similar.