A method of securing an installed metal roof deck covered with at least one layer of insulation and/or sealer. The metal roof deck is supported by a plurality of parallel metal beams. Access holes are drilled through the insulation and/or sealer at opposite ends of a beam. Self-drilling, self-tapping screws are positioned through the pilot holes and turned through the metal roof and beams. A guide is used to drill additional access holes aligned with valleys in the metal roof deck. Self-drilling, self-tapping screws are drilled through the metal roof and beams. When no access is available for visual inspection of the deck and or the beams, the same locating process is followed in a “Blindly”, or by “Feel” way.