Complete wooden floor for the living area in the attic?

Hello,

is the following floor construction of the 1st floor (= inhabited attic) possible:

New building:

Beams
On top, visible boarding made of wood 20mm (The entire ground floor ceiling will thus remain visible)
On top, 15mm OSB
On top, squared timber (10cmx10cm) as installation level at intervals of 40cm
On top, 22mm OSB

Insulation with vapor barrier etc. will certainly have to be installed in the installation level, I think. But I am still informed enough about what I have to do there.

The area is to be inhabited (i.e. bedroom, bathroom with shower and bathtub). Except for the bathroom, carpet flooring is to be laid everywhere. Tiles in the bathroom.

Thanks and regards

So this will be a normal first floor. It is just directly under the roof. There will be a completely normal staircase leading up, the height is normal. (70cm Kniestock, 35° Dach). There are also windows. The bedroom has one, the bathroom two, and the dressing room also one. I don't have any escape routes except for the staircase.

Windows can also serve as escape windows if they are of appropriate size:

Openings in windows that serve as escape routes must have a clear opening of at least 0.90 m x 1.20 m and must be positioned no higher than 1.20 m above the finished floor level.

I am an amateur, but I wonder if a vapor barrier is not wrong. To my (read) knowledge, only the exterior walls or roof need to have a vapor barrier. Otherwise maybe impact sound insulation? For the bathroom definitely flexible tile adhesive. For safety, out of ignorance, I would seal the substrate with an appropriate compound or foil, as with walk-in showers.... but really just a thought from me, not knowledge! :rolleyes:

It is also possible that no vapor barrier is necessary. I am not exactly sure. The exterior walls will be a double-layered log wall with cork insulation in between. There is no vapor barrier in that.

But because everything there is really made of wood, I want to avoid moisture and mold formation at all costs :-)