A door frame – also called a jamb or casing – provides the encasement for a door opening. There are several different kinds of door frames and all are dependent on the shape of the door opening.
Arched doors should be framed with an arched shape door opening. The materials used for this type of door jamb involve, of necessity, materials that have a certain amount of flexibility in order to achieve the arched shape. For arched doorways that are installed on particularly thick wall openings, it is possible to create stacked door frames that are similar in appearance to a door opening constructed with bricks or stones (panels are stacked vertically up the length of the opening).
Bi-fold doors are doors that are often used for closets, particularly in shallow closet spaces. Bi-fold doors are installed with runners along the top and bottom of the doors, which allow the doors to slide open and closed easily. Door frames for these openings are often framed with very simple molding that is either squared where the molding meets or with mitered corners for a smooth finished appearance. Often, bi-fold door frames are finished by either painting or staining the molding to match the appearance of the doors.