What is a common structural element that a joist sits on?

A sill plate is a critical structural element in construction that serves as the base on which joists rest. Typically made of treated wood, the sill plate is anchored to the foundation of a building and provides a solid, level surface for the joists to be installed. This connection helps distribute the load of the structure evenly across the foundation, ensuring stability and durability.

In contrast, other options pertain to different structural components. The rim joist is located at the outer edges of the joist framing and does not directly serve as the foundation for joists. A header is used to support the load above openings such as doors and windows, while a diagonal brace provides lateral support to prevent racking but does not support joists. The sill plate’s function as the foundational element for joists makes it the correct choice in this context.