Understanding the Anatomy of a Door

When you shop for a prehung steel or fiberglass entry door, you likely will notice that manufacturers often use the word frame when they refer to the external structure onto which a door is mounted by hinges. Manufacturers also refer to this structure as the jamb. A door expert with whom we spoke tells us that manufacturers are talking about the same thing—two vertical posts that are connected by a horizontal top beam.

However, frame also can refer to an internal structure that runs the perimeter of the door. Here, a frame replaces the door’s two vertical stiles (one on the lock side of the door and one on the hinge side) and two horizontal rails (one on the top and one on the bottom). Whichever internal structure is used, the door cavity is filled with polystyrene or polyurethane foam.

The door stop is molding that’s on the inside perimeter of the jamb, and it’s what makes the door stop in its closed position.