Which side outwards for vapor barrier?

[Hejnz]

Hello!
I am installing a tin roof on a barn and need to lay the condensate fabric I bought from Byggmax (https://vison.se/bison-kondensvav-genomtrampningsskydd/). It is an HD polyethylene fabric, and one side has an LD polyethylene coating. It doesn't say anywhere which side should be up/down and there are no installation instructions. One side is a bit "rougher" where you can almost feel the fibers in the fabric, and the other side is smoother. I'm thinking that the smooth side should be the one with the "LD coating," but why would the low-density side be facing out? On the corresponding side, the water has the opportunity to run into the small "fibers" that go crosswise.
I have also looked at other types of underlay fabrics, but there, both sides are usually coated with LD polyethylene.
Does anyone have any idea?

Best regards,
H

 

[huggan]

The assembly instructions are probably available on the Byggmax website if you look up the product there, the safest option if you read it.

 

[Hejnz]

The assembly instructions are probably on the Byggmax website if you look up the product there, the safest option if you read it.

No, it is not.