Wooden windows - vapour barrier?

[sludd]

I am in the process of rubbing down and repainting my wooden double glazed windows, which are about 9 years old.

I have found one of the strips of beading to be rotten and I have removed this so I can replace it.

When I removed it, I found some polythene type stuff stuck to the glass, but not adhesive on the outer side (it's fitted between the glass and the wooden beading, with the rubber sealing strip in between).

Is this a vapour barrier, or what is it if it's not this?

Also, the 4 inches or so where the wood was rotten was not stuck to the glass - do I need to replace this strip before fitting new beading, and if so, where can I source it?

 

[crank39]

I doubt its a vapour barrier but more likely to be the protective tape used around the edge of double glazed units, like a duct or tank tape, it helps against cuts when handling, its also said to be an extra barrier against water damage to the seal itself

 

[sludd]

Thanks for that

So should I be OK to go ahead and fit new beading with just the rubber seal between the bead and the glass?

 

[crank39]

Yes you'll be perfectly fine doing that