What Is a Door Jamb?

B. Turner
B. Turner
A door jamb acts as a support for a door and door frame.
A door jamb acts as a support for a door and door frame.

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.

What Are the Different Door Jamb Types?

The type of door jamb that is installed depends primarily on whether the door is an interior or exterior door. Regardless of the type of jamb that a door has, the jamb must be durable to ensure the safety and energy conservation of the room or building where the door leads.

Rabbeted Jambs

Rabbeted door jambs are found mainly in interior doors, such as those leading to bedrooms and bathrooms. The rabbet is the groove or recess that is carved into a piece of wood and provides a seal for the door to close and ensure privacy. There are two types of rabbeted jambs, single and double. Rabbeted jambs come with a built-in stop.

Split Jambs

Split jambs are used when the interior wall frame is thicker than usual, making it difficult or impossible to install a standard-sized door in the location. Split jambs, named so because they come in two split parts, are a solution to this issue. These jambs tend to be less expensive and easier to install than the other two types.

Flat Jambs

Flat jambs come in a standard measurement with a separate door stop, since they do not have anything to stop the door from closing and going through the frame too far on its own.

How To Build a Door Jamb

Door jambs have two vertical sides and a horizontal top, known as side jambs and the head jamb. Building a door jamb on your own should take no longer than a few hours.

Measure and Gather Tools

The first thing you need to do before building a door jamb is to take measurements of the space where the door is going to go. The most common height for a door is 80 inches, and widths can range between 28 and 36 inches. Some of the tools you will need throughout the process include a measuring tape, nail gun, saw, sandpaper, utility knife, wood shims, and jamb kit. While the exact building process will vary slightly depending on the type of jamb you are building, there are some common elements to the process.

Choose Materials

If you are building a door jamb for a residence, you will likely want to choose a wooden material such as hemlock, maple, white oak, or pine. Pine is the most popular type of wood, with white oak being a less expensive option. Make sure that the wood goes well with the rest of the house, and is easy to paint should this be something you would want to do now or in the future. With interior door jambs, it is less important that the materials be strong and able to withstand the elements, as is the case with exterior door jambs.

Cut

Next, you will cut the door jamb to fit the shape and measurements of the door and surrounding wall. Jambs can be cut using a miter saw, handsaw, or circular saw, with the miter saw being the best option of the three. When cutting the door jamb, leave a couple of inches of space on to account for the door's side, top, and bottom clearance. Make sure to have some sandpaper on hand to smooth down the edges of the jamb.

How To Frame a Door JambĀ 

Once the door jamb has been cut, it is ready to frame. Check the fit by placing the jamb against the door frame. If it fits, proceed to nail each wooden jamb piece to the doorframe. Repeat this process for each piece of the door jamb. After this step, you will be ready to hang the door.

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Discussion Comments

CarrotIsland

@snowywinter: Yes, there are exterior door jambs. There are several reasons why they need replacing from time to time. If your door jamb is old, it can be cracked, rotted, or damaged. You can build one fairly easily. You can buy precut boards or you can buy trim boards and do it yourself. Some of the preformed exterior doorjamb boards have weather stripping already attached to them.

In the event you need to replace a door jamb, there are several websites that show you step-by-step how to do it.

SnowyWinter

Are there exterior door jambs too?

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    • A door jamb acts as a support for a door and door frame.
      By: Kybele
      A door jamb acts as a support for a door and door frame.