What is a ceiling joist commonly supported by?

Ceiling joists are horizontal structural members that provide support for the ceilings of a building. In typical construction, these joists are commonly supported by gridders, which are beams arranged perpendicular to them, or by bearing walls that run parallel to the joists. The primary function of these supports is to carry the load of the ceiling, as well as any additional weights such as light fixtures, insulation, or even HVAC systems that may be attached to the ceiling.

Gridders, often called girders, are larger beams that anchor the ceiling joists and distribute the weight appropriately throughout the structure. Bearing walls serve a similar purpose, providing vertical support to transfer the loads down to the foundation.

The other options, while relevant in different contexts—such as chalk lines for marking straight lines during construction, chase for concealed wiring or piping spaces, and cap flashing to protect roof edges from water infiltration—do not directly relate to the specific support mechanism for ceiling joists. Understanding these distinctions is crucial for comprehending the structural integrity and framing practices involved in roofing and construction overall.