What is the bottom framing member of a door frame called?

The bottom framing member of a door frame is known as the threshold. It serves multiple essential functions in a door assembly. Primarily, thresholds provide a smooth transition between the interior and exterior of a building, helping to facilitate movement and improve aesthetics.

In addition to enhancing appearance and accessibility, the threshold offers practical benefits such as weatherproofing and insulation. It helps prevent water, debris, and drafts from entering the building, which can be particularly important in exterior door applications. Correctly installed thresholds create a seal that contributes to the overall energy efficiency of a space.

The other options refer to components of a frame but serve different purposes. A stile refers to the vertical frame pieces on the sides of the door, whereas the bottom plate and top plate are typically parts of wall framing rather than door frames. This understanding of framing components is essential for effective construction and renovation practices.