Can anyone give me a clue as to how to set this up in a composite?
I'm using Insulation 1, but it is tiny and not running perpendicular to the wall skins. I have the fill oreintation set to "fit to skin". From Help it's supposed to stretch in width to match your wall width.
Well, it seems you know everything. First create your symbol fill (or use an existing one) and then choose this fill in your composite and set it to fit to skin.
Note that when you create your symbol fill (in Options/Atributes/Fill Types) there is a little yellow square. Thís square is stretched to the width of your composite. You might also want to zoom in or out in the preview.