A mullion is a vertical element that forms a division between units of a window or screen, or is used decoratively. It is also often used as a division between double doors. When dividing adjacent

window A window is an opening in a wall, door, roof, or vehicle that allows the exchange of light and may also allow the passage of sound and sometimes air. Modern windows are usually glazed or covered in some other transparent or translucent ma ...

units its primary purpose is a rigid support to the glazing of the window. Its secondary purpose is to provide structural support to an arch or lintel above the window opening. Horizontal elements separating the head of a door from a window above are called transoms.

History

Stone mullions were used in

Armenian Armenian may refer to: * Something of, from, or related to Armenia, a country in the South Caucasus region of Eurasia * Armenians, the national people of Armenia, or people of Armenian descent ** Armenian diaspora, Armenian communities around the ...

Saxon The Saxons, sometimes called the Old Saxons or Continental Saxons, were a Germanic people of early medieval "Old" Saxony () which became a Carolingian " stem duchy" in 804, in what is now northern Germany. Many of their neighbours were, like th ...

and

Islamic architecture Islamic architecture comprises the architectural styles of buildings associated with Islam. It encompasses both Secularity, secular and religious styles from the early history of Islam to the present day. The Muslim world, Islamic world encompasse ...

prior to the 10th century. They became a common and fashionable architectural feature across Europe in

Romanesque architecture Romanesque architecture is an architectural style of medieval Europe that was predominant in the 11th and 12th centuries. The style eventually developed into the Gothic style with the shape of the arches providing a simple distinction: the Ro ...

, with paired windows divided by a mullion, set beneath a single arch. The same structural form was used for open arcades as well as windows, and is found in galleries and cloisters. In

Gothic architecture Gothic architecture is an architectural style that was prevalent in Europe from the late 12th to the 16th century, during the High Middle Ages, High and Late Middle Ages, surviving into the 17th and 18th centuries in some areas. It evolved f ...

, windows became larger and arrangements of multiple mullions and openings were used, both for structure and ornament. This is particularly the case in

Gothic cathedrals and churches Gothic cathedrals and churches are religious buildings constructed in Europe in Gothic style between the mid-12th century and the beginning of the 16th century. The cathedrals are notable particularly for their great height and their extensive u ...

where

stained glass Stained glass refers to coloured glass as a material or art and architectural works created from it. Although it is traditionally made in flat panels and used as windows, the creations of modern stained glass artists also include three-dimensio ...

was set in lead and ferramenta between the stone mullions. Mullioned windows of a simpler form continued to be used into the

Renaissance The Renaissance ( , ) is a Periodization, period of history and a European cultural movement covering the 15th and 16th centuries. It marked the transition from the Middle Ages to modernity and was characterized by an effort to revive and sur ...

and various Revival styles. Italian windows with a single mullion, dividing the window into two equal elements are said to be biforate, or to parallel the Italian bifore windows.

Design

Mullions may be made of any material, but

wood Wood is a structural tissue/material found as xylem in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulosic fibers that are strong in tension and embedded in a matrix of lignin t ...

and

aluminium Aluminium (or aluminum in North American English) is a chemical element; it has chemical symbol, symbol Al and atomic number 13. It has a density lower than that of other common metals, about one-third that of steel. Aluminium has ...

are most common, although glass is also used between windows. I. M. Pei used all-glass mullions in his design of JFK Airport's Terminal 6 ( National Airlines Sundrome), unprecedented at the time. Mullions are vertical elements and are often confused with transoms, which lie horizontally. In US parlance, the word is also confused with the " muntin" ("glazing bar" in the UK) which is the precise word for the very small strips of wood or metal that divide a sash into smaller glass "panes" or "lights". A mullion acts as a structural member, in most applications the mullion transfers wind loads and weight of the glazing and upper levels into the structure below. In a curtain wall screen, however, the mullions only support the weight of the transoms, glass and any opening vents. Also in the case of a curtain wall screen the weight of glazing can be supported from above (providing the structure can take the required loads) this puts the mullions under tension rather than compression. When a very large glazed area was desired before the middle of the nineteenth century, such as in the large windows seen in Gothic churches or

Elizabethan The Elizabethan era is the epoch in the Tudor period of the history of England during the reign of Queen Elizabeth I (1558–1603). Historians often depict it as the golden age in English history. The Roman symbol of Britannia (a female per ...

palaces, the openings necessarily required division into a framework of mullions and transoms, often of stone. It was further necessary for each glazed panel, sash or casement to be further subdivided by muntins or lead cames because large panes of glass were reserved primarily for use as mirrors, being far too costly to use for glazing windows or doors. In traditional designs today, mullions and transoms are normally used in combination with divided-light windows and doors when glazing porches or other large areas.

References

External links

* Windows Romanesque architecture {{Interwiki extra, qid=Q1291476

History

Design

See also

References

Further reading

External links