Perpendicular application of sheetrock is preferred where fire code permits because it:

The preference for perpendicular application of sheetrock primarily stems from the structural and fire resistance benefits it provides. When sheetrock is installed perpendicularly, it lays across the framing members, which helps in reducing the total number of linear feet of joints that need to be taped. This is critical because joints are potential weak points in fire-rated assemblies. Fewer joints mean less opportunity for fire to pass through, thereby enhancing the overall fire resistance of the structure.

Additionally, by minimizing the number of joints, the application process can also be made more efficient, as there is less taping and finishing work required. This contributes to durability and a better finish but does not directly relate to either cost or ease of installation in the same way that joint reduction does. The fire code favors practices that enhance safety and structural integrity, and the perpendicular application aligns with these priorities.