Final answer:
In suspended ceiling installation, the main tear rails or runners must be installed at least 3" below the existing ceiling framing to provide clearance for tiles and integrated components like lighting or ventilation. The process involves leveling, securing wall angles, and constructing a leveled grid to support ceiling tiles.
Step-by-step explanation:
When installing a suspended ceiling, a key component of the grid system, known as the main tear rails or main runners, must be installed at least 3 inches below the bottom of the existing ceiling framing. This clearance is important to allow for sufficient space for the ceiling tiles to be installed and removed easily, and to accommodate any lighting, ventilation components, or other utilities that might be part of the ceiling's infrastructure.
The installation process begins with determining the perimeter of the room and then establishing a level baseline all around it at the desired drop level. Once the correct level is marked, wall angles are attached to the wall at this height. After securing the wall angles, main tear rails are hung from the ceiling using wires or other approved methods, and they should be leveled carefully to ensure a flat ceiling surface. Cross tees are then inserted into slots on the main tear rails to create a grid. Each section of the grid should be precisely measured and leveled to accommodate the ceiling tiles. Lastly, after verifying that the grid is square and secure, ceiling tiles can be laid into the grid. Special attention should be paid to areas where light fixtures or concave mirrors might interact with the ceiling, as alterations to the grid might be required for proper fit and function.