Last edited 01 Apr 2021


The term 'jamb' typically refers to the vertical up-right components that form the sides or of door or window frames.

In relation to doors, on one side, the jamb bears the weight of the door through the hinges (the hinge jamb), whilst on the opposite side, the door latches, deadbolts and so on, when engaged, will usually extend into a recess in the jamb (the lock jamb). It is therefore important to ensure accuracy of the jamb’s plumb (verticality).

The joint between the door jamb and the surrounding walls will typically be concealed by a casing sometimes referred to as a door surround or architrave.

Window frames are typically formed by two side jambs, a horizontal cill across the bottom and a horizontal member across the top sometimes referred to as the head jamb or headjamb. On a window, the jambs can be fitted with jamb liners to improve air tightness. As with doors, a casing will generally be used to conceal the joint between the frame and the walls.

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