Hello,
I'm in the process of building a garage and have recently put up wind barrier fabric on the garage, which is now completely finished and secured with battens.
Only now did I check what I actually put up, which in hindsight was quite reckless...
At the builders' supply, I just ordered wind barrier fabric without much thought. The one I got was Icopal Windy Base.
That fabric has an Sd value of 0.4m. In comparison, their Prima fabric, or Isover's or other brands, usually have a value of about 0.04m, which is roughly 10 times more permeable.
Somewhere I read that anything under 0.5m is considered diffusion-open.
The general rule says that you should have an interior layer 5-10 times tighter than the exterior layer, and since I plan to have a vapor barrier (plastic) on the inside of the garage, this will be achieved by far. (Plastic has about 50m)
However, I'm still a bit concerned whether it's good or bad to have fabric that is a bit "tighter."
It's not certain that I will heat the garage, and if I do, it will not be more than about 10 degrees.
So what do you think? It is a wind barrier fabric, after all, so it should be intended for this purpose. I'm just a bit paranoid but still want to discuss it with someone.
I assume Icopal Windy Base has been installed on more houses than just mine...
Best regards, Henke
