A door jamb is the vertical section of a door frame, which acts as a support for the remainder of the frame, as well as the door itself. Each frame has two jambs. The hinge jamb is the side where the hinges are installed, and the strike jamb is the side where the locking mechanism latches into the strike. The jambs are also used to mount the frame to the surrounding wall. The horizontal member that connects the two jambs is called the head.
The material used to make a door jamb is largely determined by where it will be used. In most residential settings, the door frame is made of wood. It is typically hidden by casing or trim, so the type and finish of the wood is generally not important. For commercial uses, hollow metal door jambs are most common, and are made of cold-rolled steel for interior applications, or galvanized steel for exterior use. Some architects may specify frames made of stainless steel or aluminum to provide a nicer finish, while fiberglass frames are used for their durability and weather-resistance.
There are a number of components that go into making up a door jamb. There is the face of the jamb, which is the surface that is parallel to the wall. The stop of the jamb is the bump-out that holds the door in place and keeps it from swinging straight through the frame. On either side of the stop is an area known as a rabbet. The majority of door jambs come equipped with one rabbet larger than the other, meaning that the stop is not centered, though equal-rabbet frames can be custom-made.
When ordering a door frame, several details about the jambs must be determined, starting with the throat size of the jamb. The throat is the back portion of the door jamb that wraps around a wall for installation. It should be equal to the thickness of the wall where it is being installed. Next, one must specify the types of hardware to be used. Each door jamb will then be prepped with cut-outs or reinforced with steel plates to accommodate and support the hardware installation.
A variety of fasteners are used to secure the door jambs to the adjacent walls. With wood frames, most types of nails and screws are acceptable. Metal frames require specialty anchors, and generally these anchors must be ordered with the frame. For masonry walls, a T-anchor or wire anchor is welded into the jamb, then set between the layers of brick or block. A compression anchor is welded into the jamb of frames used in drywall, and can be adjusted to fit the walls after they are erected.