Frost behind insulation?

[HenrikEng]

Hello!

I've torn down a bathroom, there was a wet room mat, plasterboard, some kind of board then plastic, insulation, and then another board.

I just removed the insulation as I am going to respace to cc30, and I noticed there is frost between the outermost board and the insulation. Is it supposed to be like that? The bathroom has had a closed door and it's minus 10 outside. I have a mexitegelhus.

 

[magnu]

With subzero temperatures outside and humid indoor air inside, the indoor air tends to condense on the cold surface, and if it's below freezing, it becomes ice. The fact that the bathroom door has been closed doesn't make much of a difference. The water molecules pass through much narrower gaps according to one of the laws of thermodynamics.

 

[HenrikEng]

With sub-zero temperatures outside and humid indoor air inside, the indoor air tends to condense on the cold surface, and if it's below zero, it turns into ice. Whether the bathroom door has been closed doesn't make much of a difference. Water molecules pass through much narrower gaps according to one of the laws of thermodynamics.

Should have humidity 30-40rf in the bathroom, it's the same in the rest of the house anyway.

So I don't need to worry, in other words, just put the insulation back in place and install the flyfa panels - våtrumsgips.