Methods of forming a barrier layer on a substrate to form a halogen-free multi-layer construction configured to increase the barrier properties of the substrate are described. The barrier layer can reduce the oxygen transmission rate through the construction and can reduce the amount of air on one side of the construction. The methods include dissolving a highly amorphous vinyl alcohol polymer in a solvent to form a solution and applying the solution to the substrate. The solution is dried to form a barrier layer on the substrate. The barrier layer is continuous, relatively thin, and has a consistent thickness throughout the barrier layer, yet provides improved barrier properties. The methods can include using water-impermeable interior and exterior layers for preventing liquid water and water vapor from negatively affecting the functioning of the barrier layer, and an adhesive layer for reducing flex cracking failure of the barrier layer.