Butt hinges are the most commonly used type of door hinge. They are made of two metal plates that are connected by a steel pin. One plate is screwed to the door while the other is fastened to the frame. Butt hinges can be mortised into the door and frame or installed on the surface. The average unit is 4.5 inches high, and most doors require three hinges. Heavy or over-sized doors may require more than three hinges.
Specialty Butt Hinges
Some butt hinges are specially designed to accommodate unique door installations. Swing clear hinges have plates bent at 90 degree angles so that the door will rest outside of the travel path when fully open. Raised barrel hinges are designed for wide door frames to allow the door to open a full 90 degrees. The barrel, or pin, is slightly offset so that it will not be bound by the frame. Wide throw hinges have extra wide plates to allow a door to open past nearby trim or woodwork.
Invisible, or SOSS, hinges are fully mortised inside a door and frame so that they are not visible when the door is closed. These hinges are very expensive and are generally used on high-end applications. The door and frame must be carefully prepped to receive these hinges, and installation can be difficult and time consuming for novice installers.
Spring hinges contain tightly coiled springs tucked inside the barrel where the two plates meet. This spring causes the door to automatically shut after it has been opened. These units are commonly used on fire-rated or exterior doors in place of a closer. The closing speed associated with a particular spring hinge cannot be regulated, and they must be chosen carefully based on the size and weight of the door.
Electrified hinges are used to transport electricity to locks and other hardware devices. These hinges are equipped with a series of thin wires that provide power to electric locks, keypads and card readers. This eliminates the need for a separate power supply while helping to conceal wires from view.
Continuous, or piano hinges are made of interconnected metal plates that extend the entire length of the door. They are used on heavy doors that can't be supported by traditional hinges. These hinges are also used on doors subject to heavy abuse, such as schools or detention facilities. Continuous hinges help to evenly distribute the weight of the door along its entire height, helping to reduce maintenance needs while extending the life of the door.