Insulated metal roofing and wall systems and related methods

An insulated roof deck or wall system, comprising:

• a plurality of metal purlins, each metal purlin being configured to form a parallel array of purlins such that voids exist between the metal purlins in the parallel array;
• a plurality of outer panels, each panel being configured to be attached to the metal purlins to form an outer deck;
• a plurality of thermal insulation blocks, each thermal insulation block being disposed between the metal purlin and the outer panel;
• a cleat disposed between the thermal insulation block and the outer panel, wherein the cleat includes a protrusion which secures the thermal insulation block and inhibits lateral movement between the thermal insulation block and the cleat;
• a first insulation layer disposed between the plurality of outer panels and the plurality of thermal insulation blocks;
• a second insulation layer disposed below the first insulation layer;
• and
• a fastener, wherein the fastener is configured to secure the outer panel, the cleat, and the thermal insulation block to the metal purlin.