Before moving on to taping and finish work, the outside corners need to be protected with corner bead. Install any finish trim where a clean juncture might otherwise be a problem—such as against metal-framed windows or concrete block. Both these metal trims need to be nailed (not screwed) into wooden framing members, with the nails spaced every 9". The heads should be flat to the flange, but not driven deep enough to bend the metal.
KAY HOLMES STAFFORD