We are renovating a bathroom that has a T&G 2x6 ceiling that is also the floor above (see picture). The span is 4' (between outside wall and 4x10 beam) and is classic old Lake Tahoe framing. Our desire is to tile the ceiling and also make it more a more robust floor for the living area above. The current thought is to screw 1 1/8" plywood to the ceiling (2.25" screws) hitting every 2x6 (6" in field) and put a 1.5" angle iron ledger around the perimeter. The perimeter is a glulam (above window), 4x10 on left side of picture, and 4x10 near camera (not visible in pic). Any thougths if this will help stiffen above floor and if we are going about this the right way?