Abstract: A panel construction for roofs and the like is disclosed for use as an insulated structural roof deck and insulated structural wall which includes panels capable of being readily handled, the panels being attached to and supported by spaced long span bar joints or the like, or other structural steel framing, the panels each having a lower board preferably of gypsum to serve as a fire shield and to which at least one small structural steel stiffener or joist member preferably of I-shape and of sheet metal is secured. I-shaped joist members are also provided along one end margin and along one edge margin of each panel. The space between the internal joists and to the I-shaped margin members is filled with polyurethane foam formed along one side edge and one end edge as tongues for engagement in the I-shaped margin members. The lower board is preferably vented to permit the escape of gas generated by exposure of the foam to very high temperatures.