Radiant barrier decking (like TechShield and PolarPly) works and can actually be quite economical if you are having a new roof deck added. The foil is applied to the plywood and then laid face down (toward the building’s interior) as it is installed. This application leaves the foil with an air gap so the foil works to block radiant heat from emitting (emissivity) into the warehouse.
The photo above shows the radiant barrier decking facing the open air.
However, the one down side to radiant barrier decking is that it doesn’t take in to account thermal bypass on the rafters (meaning the heat is still moving through the rafter ends that are not covered with radiant barrier, and then radiates off the ends into the space below). Using WarehouseFoil™ across the rafter bottoms does not allow for thermal bridging so overall you get a better performance from using it over the OSB products.