What does the bottom chord of a truss serve as?

The bottom chord of a truss serves a critical structural purpose, functioning as a ceiling joist. In a typical truss design, the bottom chord is the horizontal or sloped component that connects the ends of the truss members at the bottom. This element helps distribute loads and provides stability to the truss system, effectively supporting the weight of ceilings, floors, or roofs above.

In residential construction, the bottom chord often acts as a support for the ceiling, which is why it is categorized as a ceiling joist. This structural element is essential for maintaining the overall integrity of the building and ensuring that loads are transferred correctly. The ceiling joists also play a role in creating a flat surface for attaching drywall or other ceiling finishes.

While other choices may relate to building components, they do not specifically describe the function of the bottom chord. For instance, exterior walls are supported by vertical elements such as studs, and aesthetic features are not structural components. An insulation barrier, on the other hand, is not a direct function of the truss but relates to thermal resistance in the structure rather than providing support for ceilings. Therefore, the classification of the bottom chord as a ceiling joist accurately reflects its role in structural engineering.