When installing foil-backed gypsum panels as exterior sheathing, which side should face outward?

When installing foil-backed gypsum panels as exterior sheathing, the gypsum side should face outward. This is because the foil backing is designed to act as a vapor barrier, preventing moisture from penetrating the wall assembly. By placing the gypsum side facing the exterior, you ensure that the foil backing is positioned correctly to perform its intended function of controlling moisture flow.

This arrangement minimizes the risk of condensation forming in the wall cavity, which can lead to mold growth and deterioration of materials. Additionally, the foil back serves to reflect heat, providing an extra layer of insulation and improving the energy efficiency of the building. Thus, the proper orientation of the panels is crucial for maximizing their benefits in the construction process.

The other options do not provide the correct application of the materials as they ignore the key function of the foil backing in managing moisture and thermal efficiency, which can lead to potential building issues over time.