How do you guys retrofit vapour barriers for junction boxes and in-wall speakers on outside walls? Or do you even bother?

The lack of responses probably means nobody can directly do this. I looked at it just after you posted it and really had no good answer.

But here's my improvisation: If you are installing something like the new Niles weatherproof volume controls, then they come with a rubbery panel that goes between the cover plate and the electrical box; these make a decent vapor barrier, especially if siliconed in place. If you are installing something else, then you just have to do what you can. For a phone jack, for instance, well, you can't keep vapor from going into a phone jack, so it can't be done. You can silicone the cover plate on and use a weatherproof cover over that, but that's about it.

thanks for the suggestion. it seems it's not really a troubling issue then. what exactly happens in the long run if a vapor barrier is left out? will mold be produced or will drywall crumble or something?

I live in Southern California where we have pretty dry weather, so I am sure the vapor barriers are not really tested by the elements here.

You should look up a contractor on the internet in, say, Florida, then one in Minnesota, and ask for some information. I find if I call someone, tell them I am too far away from them to compete with them but need some basic information on a concept they are really familiar with, they usually are very happy to tell me what they know.

Oh, yeah, I did not look at your profile just now, but call someone local, too. Or maybe your local building and safety department; get an engineer. Be sure to remain anonymous in case they decide to be zealous.

You can buy vapour barrier junction boxes (thick plastic shaped like a junction box) in places like Home Depot ...etc in Canada. The other trick is just to use a piece of vapour barrier that conforms to the shape of the device.

The important issue is not the shape of the plastic behind the function box, but rather the effectiness of the seal of the plastic behind the junction box and the rest of the vapour barrier. As you well know this is the only way only stop air leaks (something that is important in Canada and northern US). The best tape for this type of application is a red mylar tape (made by 3M, Tuck Tape ...etc.) specifically designed for vapour barriers and typar. Oh, it's not cheap, but it works real well.

In addition, it shouldn't be a question of if you use vapour barrier on an outside wall, it should only be a question of what you use. If you are not using a vapour barrier on an outside wall you will be causing severe consendation problems (this applies to any house in Canada). The one thing to remember with outside walls, in cold climates, is that you have to maintain insulation value as well as air seal. If you're unsure of the proper insulation/vapour barrier methods are get a copy of the National Building Code.

Also, if you're a dealer, and you're looking for speaker back boxes in Canada contact Positive Marketing. If you're not a dealer, buy the speaker back boxes through a dealer.