I'd say that for something like a fascia, that's probably a better way to go. Depending on just how much fiberglassing you need to do (i.e. just a small amount of trim, or a huge enclosure), you might want to look into a product called Solarez. It's basically premixed fibers and epoxy in a tube. You squirt it out into whatever shape or mold you need, and put it in the sun to cure for three minutes. It's intended for repairing dings, cracks, and holes on surfboards, and, having used it a couple times now, it's amazing stuff, and incredibly easy to use.