Vapor barrier plastic against timber

[norrbottenstorpet]

There are many opinions about plastic or no plastic in old houses, we will skip that discussion.

Now I am building a new (modern) roof structure on top of the old one, and this includes vapor barrier plastic. However, it involves the difficulty of sealing against an existing uneven timber frame in a couple of places. Does anyone have any tips? Can you put some form of rubber strip on the inside of the plastic that can then be clamped under a beam, or?

 

[sune73]

Butyl tape maybe

 

[xyle]

Plastic wrap as best as possible against the timber then seal the gaps?

 

[norrbottenstorpet]

Butyl tape maybe

Is butyl tape expanding in any way?

Maybe expanding fönsterdrev under a well-screwed batten? https://www.byggmax.se/fonster/montering-och-tillbehor-fonster/fonsterdrev-p129130 The downside is the price (need at least 100 m).

Seal as well as possible against the timber then fill the gaps?

Do you know anything that adheres well to the plastic? It usually isn't easy to adhere to, e.g., a foam sealant typically doesn't work against PE plastic.

 

[sune73]

Is butyl tape expanding in any way?

Maybe expanding window foam under a well-screwed frame? [link] The downside is the price (needs at least 100 m).

Do you know anything that adheres well to plastic? It usually isn't easy to attach to, for example, a sealant foam usually doesn't work against PE-plastic.

No, butyl tape is not expanding but adheres to the plastic.