What is the primary stated purpose of a Sill Plate?

• A. To connect joists
• B. To distribute weight to the foundation
• C. To keep out wood boring insects
• D. To provide vertical support

Answer: (C)

The sill plate sits on the foundation and is typically pressure-treated to resist rot and insect attack. Its primary stated purpose is to act as a barrier against wood‑boring insects at the joint where the framing sits on the foundation. By sealing and protecting this interface, it helps prevent termites or other pests from entering the wooden structure. It also provides a solid nailing surface for attaching wall studs and anchors, and while it participates in load transfer to the foundation, the attribute most emphasized in standards is pest resistance at the connection between foundation and framing. The other functions listed—connecting joists, providing vertical support, or being the main means of distributing weight—are roles filled by other components in the framing system.