These panels are commonly used for ceilings or for walls that require a prescribed fire-resistant rating.
When installed on ceilings, 5/8-inch-thick panels are less susceptible to sagging between the joists than 1/2-inch panels. Adding popcorn texture or another type of heavy surfacing material can add to the weight problem, making 5/8-inch drywall a better choice for ceilings.
Thicker drywall may be required by code for any wall or ceiling covered with a texture or skim coat where studs or joists are spaced 24 inches on-center rather than 16 inches.
This thicker drywall is often called fire-resistant drywall. Common walls between residential living spaces and attached garages, for example, require a fire-resistant construction, as do furnace rooms. This fire resistance can also be achieved by installing multiple layers of thinner drywall panels.