Siporex wall without plastic film...

[MathiasS]

I am currently adding extra insulation to a Siporex wall. Insulation manufacturers do not recommend installing any plastic film internally to prevent moisture transport, nor is there one present today. The Siporex elements are made with double layers with foam plastic in between. In other words, the wall is probably quite tight.

I am now wondering if one should add a plastic film if mounting OSB+gypsum internally?

Wallpapers etc. do not appear to be moisture-affected at all, so I find it hard to believe it would be an issue with the OSB.

What does the expertise say? Plastic or skip it?

 

[ClasseClas]

I'm no expert but I think a little...

Check the vapor resistance of the cell plastic in Siporex elements compared to building foil. If it's close to the resistance of building plastic, then to me it's redundant and that's not a desirable situation. You are aware of the discussions regarding waterproofing in tiled bathrooms where prefab walls already have foil behind OSB/plasterboard or double plasterboard or similar.

 

[JonasHolm]

Hello Mathias (and everyone else)

Have you heard anything from the insulation manufacturers about what they recommend for a massive lightweight concrete wall regarding additional insulation and plastic film?

/Jonas

 

[MathiasS]

Classe - I reason pretty much like you.

Jonas - Nope, I have only inquired about Siporex walls and don't know what applies to other stone walls.

 

[JonasHolm]

I realized that I actually asked Isover about this a while ago.
Sometimes one is really forgetful... [smiley=2vrolijk_08.gif]

They recommend a vapor retarder like Mataki Halotex on the inside.

/Jonas