What is located at the bottom of a window sash?

The bottom rail of a window sash is an essential component that serves multiple purposes. It is the horizontal piece located at the bottom edge of the sash, which is the movable framework that holds the glass in place. The bottom rail provides structural support and stability to the sash, ensuring that it remains functional and durable over time. It also acts as a surface for weatherstripping, which helps seal the window against air and water infiltration, contributing to energy efficiency and comfort within a building.

Understanding the roles of different parts of a window sash is vital for recognizing how they contribute to the overall performance of the window. In contrast, other components such as the top rail, muntins, and stiles have distinct locations and functions—making it clear why the bottom rail is the correct answer in this context.