Confirming Outer boundary polygon limitations

[Keith W]

I'm just finishing putting together a site plan, which was a little frustrating because I had too much hope for outer boundary polygons, I think.

Turns out, I can only use them on items on the current layer (which means I can't turn on a bunch of layers to use as a "trace" for the outside plan boundaries of the building), and I can't use it on symbols, which means that even if I go to each relevant layer, do an OB polygon on whatever's there, move it to my working layer, and then add all those, this strategy won't work for roofs or floors (which, I think for this purpose, are symobols, or for some other reason can't OB or IB polygonned).

Does this sound right? Have I missed anything? Is there a better way to do this, rather than just turn on relevant layers and snap the perimeter, which would have taken 1 minute but where's the fun in that?

Keith