Like most things, exterior doors are the sum total of many parts, each with a unique function and purpose. Knowing these different parts by name can be a big help when it comes to understanding performance.
Frame is the outer structure in which the exterior door system is supported. It is most often made of wood to facilitate being fastened to the studs of the rough opening.
Stiles are the continuous vertical supports in the exterior door. In a wood exterior door they are exposed. In steel and fibreglass the actual stiles covered by the outer skin. Often the outside is embossed to have the appearance of stiles.
Rails are the continuous horizontal supports in the exterior door. Their number can vary according to the design of the exterior door itself.
Sill is the bottom portion of the frame against which the bottom of the exterior door rests when it is closed. If it is metal on the surface for durability, it is important that it incorporates a thermal break to reduce conductive heat loss.
Bottom Sweep is the adjustable continuous barrier attached to the bottom of the exterior door to create an effective barrier to air leakage and drafts.
Weatherstripping is a flexible continuous gasket that ensures a tight seal between the exterior door and the frame when the door is closed.
Brick Mould is attached to the frame on the exterior side to create a finished overlap on the brick or side material covering the exterior of the building.
Panels are the sections of the exterior door held in place by the stiles and rails. On a wood exterior door, they are part of the construction. On steel, fibreglass, vinyl exterior doors they are embossed on the surface of the skin.
Foam core is an insulating agent injected into the core of steel and fibreglass exterior doors.
Glass inset is a glazed unit installed in the structure of the exterior door itself. There can be one or more in an exterior door and they replace panels from a design perspective.
Side lites are the glazed units that can be incorporated on either one side or both sides of the exterior door.
Transom is the glazed unit that spans the top of an exterior door entry system