The terms "door frame" and "casing" refer to different components of a door installation. Here's an explanation of each:
Door Frame: The door frame, also known as the door jamb, is the structural framework that surrounds and supports the door. It consists of vertical side jambs (also called door stiles) and a horizontal head jamb. The frame is typically made of wood, metal, or composite materials. Its primary function is to provide stability and support for the door, allowing it to swing open and shut. The door frame is installed within the rough opening of the wall during construction or renovation.
Casing: The casing, also called the door trim or door molding, is the decorative finishing material that covers the joint between the door frame and the adjacent wall. Casing serves both aesthetic and functional purposes. It enhances the appearance of the doorway, concealing any gaps or rough edges between the frame and the wall. Additionally, casing can help protect the edges of the door frame from damage and provide a transition between the wall surface and the door. Casings are available in various styles and profiles, such as simple and flat, or ornate and detailed, allowing customization to match the architectural style of the space.
In summary, the door frame is the structural framework that supports the door, while the casing is the decorative trim that covers the joint between the frame and the wall, providing a finished appearance.