Floor construction with wooden substructure

All right, but the concern is less about the installation method of the sleepers (screwed or floating). Because just because you screw down the sleepers, a vapor barrier (if required for tiles) does not become unnecessary.

Therefore, you should think about the installation method anyway, I think the effort is lower with floating installation (no drilling). But I hope someone here still has an answer regarding the necessity of a vapor barrier for tile flooring.

Just because you screw the battens doesn't mean a vapor barrier (if required for tiles) becomes unnecessary.

If there are about 60 screws in the vapor barrier foil, does that not make it unnecessary?

Then I'll just lay one in...

I didn't say that, I already said that a floating installation is easier. Theoretically, I think you would have to seal each drill hole afterwards to maintain the effect of the vapor barrier. Nevertheless, it does not become obsolete by screwing, because fixing the battens with screws does not change the necessity at all (if it is indeed necessary).

If you really want to screw the battens (for whatever reason), then do it. I'm just trying to help you with my (read) knowledge.

If you absolutely want to screw the battens (for whatever reason), then go ahead.

Thanks. I can answer the why: they won't move anymore.

That way I can easily align them straight, lay the insulation, and comfortably wiggle the OSB boards on top... It's simply more stable.
Even if I still have to compensate for some unevenness in places, I can much more easily prop up the battens locally. Loosen screws, slide in spacers underneath, tighten screws, holds.

But I'll just wait for a few more comments and then decide – the floor will definitely go in next week.

As I said, since I only have secondhand knowledge (mostly from the installation instructions of the manufacturers), I can only relay what is written there.

However, what you say about the movements of the construction also sounds logical. I think I will still install it as a floating floor; sometimes I still believe in the goodness of people and that those who create such installation instructions have put some thought into it.

I assume that due to the high inherent weight of the OSB boards and the subsequent floor structure above, there isn’t too much movement even with a floating installation.

But a different question out of interest: why are you actually making such a complex structure? Do you, like me, have height differences to bridge or do you want to create an installation level?

I need to raise it by 73 mm to align the kitchen with the living room.

The installation instructions are probably correct - but also rather not designed for "on finished tiled floor."

As far as stability is concerned, I have no worries about the finished floor. I just imagine that at the beginning you will swear a lot because the slats keep shifting. Especially when laying the insulation wool before the first OSB boards are placed on top.