What must be in place when new coverings create a concealed space with combustible materials?

When new coverings create a concealed space with combustible materials, having gypsum board in place is essential because it acts as a fire-resistive barrier. This means that it can slow down the spread of fire and provide occupants additional time to safely evacuate the building. Gypsum board has specific fire-rated properties that help ensure that any potential fire in the concealed space does not propagate quickly to other areas of the structure, especially in spaces where combustible materials might be present.

In contrast, while vapor barriers, reflective insulation, and air barriers have their respective functions in building construction, they do not provide the same level of fire protection that gypsum board does. Vapor barriers are primarily used to control moisture, reflective insulation is designed to manage temperature efficiency, and air barriers help in controlling air leakage; however, none of these materials specifically address the need for fire resistance in concealed spaces containing combustible materials, making gypsum board the appropriate choice in this context.