House wrap quality
 

So, a few months ago I was talking with my cousin who is a carpenter. He went to some green building event with seminars and stuff. He said that there apparently is a pretty large difference between different brands of house wrap (tyvek). Some block air really well while others don't.

Has anyone else heard this, or read about it? Links to articles?

I'm in the midst of a new housebuild and did a bit research on the various housewraps available. I ended up using Typar. It's not just about blocking air. Some don't do a very good job with moisture- which can and will lead to the growth of mold. Just some personal experience. Building wraps have come a long ways since Tyvek. Even the home supply stores sell their own brands of wraps. Another thing to look at, especially if doing a D.I.Y. project is how well it will 'weather' exposed. Some brands will degrade significantly in as little as a month, unless covered.