Gypsum board products used in a horizontal diaphragm ceiling must be installed how in relation to ceiling framing members?

Gypsum board products used in a horizontal diaphragm ceiling must be installed perpendicular to the framing members to ensure proper structural integrity and support. This perpendicular orientation provides several advantages.

First, it enhances the overall strength and rigidity of the ceiling assembly, distributing loads more effectively across the framing members. When joints in the gypsum board are staggered and aligned with the framing, it minimizes the chances of cracking and provides better resistance to bending and lateral loads.

Second, installation perpendicular to the framing helps to facilitate proper fastening. Fasteners must be driven into the framing members at appropriate intervals, and aligning the boards perpendicularly maximizes the area where the fasteners can securely attach to the framing, ensuring a stable finish.

Choosing the correct orientation is critical for achieving the desired performance characteristics of the ceiling, including fire resistance and sound attenuation. Therefore, the correct answer emphasizes the importance of this installation method for both safety and compliance with building codes.