Interior insulation in log houses - best method?

[Andreas12345]

I plan to insulate my timber house with 45 mm glass wool on the inside. The logs are probably about 150 mm thick. The room to be insulated is on the ground floor, so there is a floor and an intermediary joist.

1. Should the vapor barrier be positioned against the timber or "on top of" the insulation? If placed on top, it would be punctured when you start mounting things on the walls.

2. How do you attach the vapor barrier to the intermediary joist? There will certainly be an edge on the plastic where it ends against the intermediary joist.

 

[Jonatan79]

You should not build with plastic in such an old wall, the wall needs to "breathe" and should not be enclosed as it can create moisture problems. I'm unsure if you should even have a windstopper in between since it's the inside.

 

[Andreas12345]

The issue of plastic in timber houses has been debated endlessly, but I haven't seen any concrete and practical studies, except for this thesis:

https://uu.diva-portal.org/smash/get/diva2:697670/FULLTEXT01.pdf

It doesn't help at all that "the house breathes" if the temperature between the insulation and the timber frame is too low.

 

[Marcussjogren]

As I understand it, the choice of hygroscopic insulation is much more important than whether or not plastic is chosen. Wood fiber or cellulose insulation can absorb and release quite a lot of moisture without damaging the adjacent wood structure.

 

[shieldfire]

The standard method for log houses is usually to seal between the logs with lindrev, perhaps depending on how old the house is.