Hi all.

I'm a total noob who's going to use laminate to cover my apartment's floor. I leave on the 2nd floor of an old apartment building and because the floor wasn't properly levelled beforehand, the tiles were removed and it was levelled with a layer of concrete (if that's the correct word, I'm not from an english speaking country).

So my question is regarding underlayment. I hadn't done my homework when I got the underlayment went with what was advised in the shop, I think mine is simple foam. They had only two kinds, the other option being with moisture protection but the seller said I shouldn't need it in my case (I don't trust shop employees where I live much though).

From what I'm reading about underlayment if the subfloor is concrete then moisture is a factor and I picked the wrong one, but I wonder whether that applies only to ground floor subfloor or as in my case also upper floors. Pardon my ignorance but I don't see why should there be much moisture in the upper floor.

Hopefully your answers can clarify that.