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Interior elevation of a Gothic cathedral, with clerestory highlighted. Clerestory diagram.png
Interior elevation of a Gothic cathedral, with clerestory highlighted.
The church of St Nicholas, Stralsund in Germany - the clerestory is the level between the two green roofs, reinforced here by flying buttresses Stralsund, st Nikolai (2007-01-24) d.JPG
The church of St Nicholas, Stralsund in Germany – the clerestory is the level between the two green roofs, reinforced here by flying buttresses

In architecture, a clerestory ( /ˈklɪərstɔːri/ KLEER-stor-ee; lit.'clear storey', also clearstory, clearstorey, or overstorey) is a high section of wall that contains windows above eye level. Its purpose is to admit light, fresh air, or both.


Historically, clerestory denoted an upper level of a Roman basilica or of the nave of a Romanesque or Gothic church, the walls of which rise above the rooflines of the lower aisles and are pierced with windows.

Similar structures have been used in transportation vehicles to provide additional lighting, ventilation, or headroom.


The walls of the clerestory of the basilica-shaped cathedral of Monreale, Italy are covered with mosaic Monreale.jpg
The walls of the clerestory of the basilica-shaped cathedral of Monreale, Italy are covered with mosaic

Ancient world

The technology of the clerestory appears to originate in the temples of ancient Egypt. The term "clerestory" is applicable to Egyptian temples, where the lighting of the hall of columns was obtained over the stone roofs of the adjoining aisles, through gaps left in the vertical slabs of stone. Clerestory appeared in Egypt at least as early as the Amarna period. [1]

In the Minoan palaces of Crete such as Knossos, by contrast, lightwells were employed in addition to clerestories. [2]

According to Biblical accounts, the Hebrew temple built by King Solomon featured clerestory windows made possible by the use of a tall, angled roof and a central ridgepole. [3]

The clerestory was used in the Hellenistic architecture of the later periods of ancient Greek civilization. The Romans applied clerestories to basilicas of justice and to the basilica-like bath-houses and palaces.

Early Christian and Byzantine basilicas

Early Christian churches and some Byzantine churches, particularly in Italy, are based closely on the Roman basilica, and maintained the form of a central nave flanked by lower aisles on each side. The nave and aisles are separated by columns or piers, above which rises a wall pierced by clerestory windows.

Malmesbury Abbey, Wiltshire, England. The nave wall is divided into three stages: the upper stage with windows is the clerestory, beneath it is the triforium, and the lowest stage is the arcade. Malmesbury.abbey.clerestory.arp.jpg
Malmesbury Abbey, Wiltshire, England. The nave wall is divided into three stages: the upper stage with windows is the clerestory, beneath it is the triforium, and the lowest stage is the arcade.

Romanesque period

During the Romanesque period, many churches of the basilica form were constructed all over Europe. Many of these churches have wooden roofs with clerestories below them. Some Romanesque churches have barrel-vaulted ceilings with no clerestory. The development of the groin vault and ribbed vault made possible the insertion of clerestory windows.

Initially the nave of a large aisled and clerestoried church was of two levels: arcade and clerestory. During the Romanesque period, a third level was inserted between them, a gallery called the "triforium". The triforium generally opens into space beneath the sloping roof of the aisle. This became a standard feature of later Romanesque and Gothic large abbey and cathedral churches. Sometimes another gallery set into the wall space above the triforium and below the clerestory. This feature is found in some late Romanesque and early Gothic buildings in France.

The oldest glass clerestory windows still in place are from the late eleventh century, found in Augsburg Cathedral in Bavaria, Germany.

Gothic period

The clerestory of Amiens Cathedral in northern France Cathedrale d'Amiens - Grandes verrieres et voutes de la nef.jpg
The clerestory of Amiens Cathedral in northern France

In smaller churches, clerestory windows may be trefoils or quatrefoils. In some Italian churches they are ocular. In most large churches, they are an important feature, both for beauty and for utility. The ribbed vaulting and flying buttresses of Gothic architecture concentrated the weight and thrust of the roof, freeing wall-space for larger clerestory fenestration. Generally, in Gothic masterpieces, the clerestory is divided into bays by the vaulting shafts that continue the same tall columns that form the arcade separating the aisles from the nave.

The tendency from the early Romanesque period to the late Gothic period was for the clerestory level to become progressively taller and the size of the windows to get proportionally larger in relation to wall surface, emerging in works such as the Gothic architecture of Amiens Cathedral or Westminster Abbey, where their clerestories account for nearly a third of the height of the interior. [4]

Modern clerestory windows for energy-efficient buildings

Modern clerestories often are defined as vertical windows, located on high walls, extending up from the roofline, designed to allow light and breezes into a space, without compromising privacy. Factory buildings often are built with clerestory windows; modern housing designs sometimes include them as well.

Modern clerestory windows may have another especially important role, besides daylighting and ventilation: they can be part of passive solar strategies, in very energy-efficient buildings (passive houses and zero-energy buildings). [5]

To that end, clerestories are used in conjunction with stone, brick, concrete, and other high-mass walls and floors, properly positioned to store solar heat gains during the hotter parts of the day – allowing the walls and the floor to act as a heat bank during the cooler parts of the day. [6]

Clerestories – in passive solar strategies – should be properly located (typically in the sunny side of the building) and protected from the summer's sun by rooflines, overhangs, recessed thick walls, or other architectural elements, in order to prevent overheating during the cooling season.


Barney and Smith Car Company clerestory cars on display at the Mid-Continent Railway Museum in North Freedom, Wisconsin Passenger car GN 3261 20041010.jpg
Barney and Smith Car Company clerestory cars on display at the Mid-Continent Railway Museum in North Freedom, Wisconsin

Clerestory roofs were used on railway carriages (known as "clerestory carriages") from the mid-nineteenth century to the 1930s. [7] [8]

The first Pullman coaches in England had clerestory roofs, and were imported and assembled at Derby, where Pullman set up an assembly plant in conjunction with the Midland Railway, a predecessor of the London Midland and Scottish Railway (LMS). The first coach, a sleeping car named "Midland", was assembled and ready for trial-running in January 1874. [9]

The last clerestory-roofed trains on the London Underground were the 'Q' stock, which were withdrawn from operation in 1971. [10]

Clerestories were also used in early double-decker buses, giving better ventilation and headroom in the centre corridor, as well as better illumination. [11]

The Volkswagen Type 2 Kombi, or Transport, commonly called the Microbus, came in a deluxe version with clerestory windows. VW made the Samba from 1961 to 1967 in several versions, which had as many as 23 windows, and it is highly prized by collectors.

The clerestory is known as "mollycroft roof", as well, especially in Romany and other caravans, eg, vardos.

See also

Related Research Articles

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Romanesque architecture is an architectural style of medieval Europe characterized by semi-circular arches. There is no consensus for the beginning date of the Romanesque style, with proposals ranging from the 6th to the 11th century, this later date being the most commonly held. In the 12th century it developed into the Gothic style, marked by pointed arches. Examples of Romanesque architecture can be found across the continent, making it the first pan-European architectural style since Imperial Roman architecture. The Romanesque style in England and Sicily is traditionally referred to as Norman architecture.

<span class="mw-page-title-main">Gothic architecture</span> Architectural style of Medieval Europe

Gothic architecture is an architectural style that was prevalent in Europe from the late 12th to the 16th century, during the High and Late Middle Ages, surviving into the 17th and 18th centuries in some areas. It evolved from Romanesque architecture and was succeeded by Renaissance architecture. It originated in the Île-de-France and Picardy regions of northern France. The style at the time was sometimes known as opus Francigenum ; the term Gothic was first applied contemptuously during the later Renaissance, by those ambitious to revive the architecture of classical antiquity.

<span class="mw-page-title-main">Winchester Cathedral</span> Church in Hampshire, United Kingdom

The Cathedral Church of the Holy Trinity,Saint Peter, Saint Paul and Saint Swithun, commonly known as Winchester Cathedral, is the cathedral of the city of Winchester, England, and is among the largest of its kind in Northern Europe. The cathedral is the seat of the Bishop of Winchester and is the mother church for the ancient Diocese of Winchester. It is run by a dean and chapter, under the Dean of Winchester.

<span class="mw-page-title-main">Architecture of cathedrals and great churches</span> How large Christian houses of worship are built

The architecture of cathedrals and great churches is characterised by the buildings' large scale and follows one of several branching traditions of form, function and style that derive ultimately from the Early Christian architectural traditions established in Late Antiquity during the Christianization of the Roman Empire.

<span class="mw-page-title-main">Lisbon Cathedral</span> Roman Catholic Cathedral located in Lisbon, Portugal

The Cathedral of Saint Mary Major, often called Lisbon Cathedral or simply the , is a Roman Catholic cathedral located in Lisbon, Portugal. The oldest church in the city, it is the seat of the Patriarchate of Lisbon. Built in 1147, the cathedral has survived many earthquakes and has been modified, renovated and restored several times. It is nowadays a mix of different architectural styles. It has been classified as a National Monument since 1910.

<span class="mw-page-title-main">Triforium</span> Area of a church or cathedral

A triforium is an interior gallery, opening onto the tall central space of a building at an upper level. In a church, it opens onto the nave from above the side aisles; it may occur at the level of the clerestory windows, or it may be located as a separate level below the clerestory. Masonry triforia are generally vaulted and separated from the central space by arcades. Early triforia were often wide and spacious, but later ones tend to be shallow, within the thickness of an inner wall, and may be blind arcades not wide enough to walk along. The outer wall of the triforium may itself have windows, or it may be solid stone. A narrow triforium may also be called a "blind-storey", and looks like a row of window frames.

<span class="mw-page-title-main">Rib vault</span> Architectural feature to cover a wide space

A rib vault or ribbed vault is an architectural feature for covering a wide space, such as a church nave, composed of a framework of crossed or diagonal arched ribs. Variations were used in Roman architecture, Byzantine architecture, Islamic architecture, Romanesque architecture, and especially Gothic architecture. Thin stone panels fill the space between the ribs. This greatly reduced the weight and thus the outward thrust of the vault. The ribs transmit the load downward and outward to specific points, usually rows of columns or piers. This feature allowed architects of Gothic cathedrals to make higher and thinner walls and much larger windows.

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