ToasterEric

So what all at means is we should "shiver in the dark"?

I would have to disgree with the concept of providing a vapor retarder on BOTH sides of a wall sytem. Yes vapor drive happens in both direction depending on the time of year and climate. Yes spray polyurethane foam is an effective vapor retarder by itself. But that is the point - as long as the spay poly is the sole insulating material, it is very effective.

The problem with the subject wall system in the GBA article is that it used both rigid foam and batt insulation and threw in an additional vapor retarder to boot.

A better solution would have been to increase the amount of rigid insulation and eliminate the batt entirely. Then place the vapor retarder on the exterior side of the sheathing and not inside behind the gypsum board.

The title of this article should have been "Too Many Vapor Barriers Are a Bad Thing". The wall assembly on which the GBA article is based contains two - the poly, and the rigid foam insulation. The advice is to get rid of one of them. This is sound advice but in my opinion their recommendation gets rid of the wrong one.

As an indusrty professional who relies upon the code, I feel that the issue to be angry about is the manner in which the code consensus process was co-opted to assure this requirement was added to the code. Fire-fighters packed the house to ensure the vote went their way. It was a mugging by "majority rules" not a consensus.

Maybe next round, the masons will pack the house and all houses will have to be made of masonry.

And then after that the metal stud industry will show up...

And then the bidet industry...

I suspect that unless the fire-fighters tend to continue packing the house at every ICC meeting, the requirement will be softened (or eliminated) and some options and exceptions will be made available with the next consensus cycle.

I think that the consensus process needs to be changed so that this can't happen again.

If this issue bothers you then you should lobby the jurisdictions you work in to ammend the code at its adoption and eliminate the requirement.