ᐅ How do you assess the ISOWOOD concept?

We are currently looking for a general contractor for our building project and came across ISOWOOD Haus. I find the concept very interesting, but I wonder if it truly delivers on its promises. In particular, the fact that they build without a vapor barrier and without controlled residential ventilation – I’m not sure if that can actually work. Maybe you could share your opinions on this, or perhaps you have even built with ISOWOOD and have a few years of living experience with their homes.

It will probably work. Wood fiber is not quite as sensitive to moisture and is vapor permeable. However, I still wouldn’t build without ventilation, as fresh air needs to get into the house somehow.

The wood fiberboard is only on the outside. Inside, there is an OSB board with drywall installed on top. The OSB board essentially acts as a vapor barrier, doesn’t it? Or can moisture also diffuse through it?

Yes, OSB acts as a vapor retarder. The key difference compared to other constructions is that the wood fiber insulation between the studs is not susceptible to moisture, whereas mineral wool is.

Then I still don’t understand what potential moisture in the insulation has to do with the ventilation system. If the OSB board is vapor-retardant, moisture in the insulation would not be removed by the ventilation system. Or am I missing something here?

Karlsson schrieb:

We are currently looking for a general contractor for our building project and came across ISOWOOD Haus. I find the concept very interesting, but I wonder if it really delivers what it promises. Especially the fact that they build without a vapor barrier and without mechanical ventilation with heat recovery, I can’t really assess if that can work.

That sounds like a general contractor search done without me—unnecessarily in your case 😉 Mechanical ventilation with heat recovery is something you can choose to have or not, but it should never be "replaced" by a wall assembly. If a general contractor told me their magic wall makes mechanical ventilation with heat recovery (assuming you even want one) unnecessary, I would at least keep my distance or even run away. If I were you, I wouldn’t go searching without experienced support (I already pointed you to alternatives).

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