Flying buttress
A ramping arch conveying lateral forces from a wall to a massive pier.
The flying buttress is a lateral-support system composed of a ramping arch, known as the flyer, which extends from the upper portion of a wall to a massive pier situated away from the building. This design conveys to the ground the outward lateral forces generated by stone vaulted ceilings and wind-loading on roofs. Unlike a traditional buttress, it is not in contact with the wall at ground level, instead transmitting forces across the intervening space via either a segmental or quadrant arch. The system has two main parts: the vertical masonry pier and the bridging arch.
This architectural element developed during late antiquity and flourished in the Gothic period (12th–16th centuries). Early examples appear on the Basilica of San Vitale in Ravenna and the Rotunda of Galerius in Thessaloniki. Its precursors are found in Byzantine and Romanesque architecture, such as at Durham Cathedral, where arches hidden under the gallery roof transmitted lateral thrust from stone vaults to massive outer walls. By the 1160s, architects in the Île-de-France region employed longer, finer arches running from the clerestory wall over the side-aisle roof to heavy vertical buttresses. The flying buttresses of Notre Dame de Paris, constructed in 1180, were among the earliest in a Gothic cathedral, and similar supports were used around the same time for the apse of the Church of Saint-Germain-des-Prés, completed in 1163.
The advantage of this system is that outer walls need not be massive; instead, vertical mass concentrates on external buttresses, allowing larger windows, often glazed with stained glass. Early designs, such as at Chartres Cathedral (circa 1210) and the apse of Saint Remi Basilica (circa 1170), were heavier than necessary. Later architects refined the design, narrowing the flyers, sometimes to a single thickness of voussoir with a capping stone, as seen at Amiens, Le Mans, and Beauvais Cathedrals. Late Gothic flying buttresses sometimes featured flyers decorated with crockets and sculpted figures in niches. The Renaissance abandoned the flying buttress in favor of thick-wall construction, though the design was revived in the early 20th century by Canadian engineer William P. Anderson for lighthouses.
- field
- Architecture, Structural Engineering
- known_for
- Lateral-support system for stone vaulted ceilings, enabling large windows and Gothic cathedrals
- period
- Late antiquity; flourished during Gothic period (12th–16th c.)
- early_examples
- Basilica of San Vitale (Ravenna), Rotunda of Galerius (Thessaloniki)
Lore & Background
The flying buttress was developed during late antiquity and later flourished during the Gothic period (12th–16th c.) of architecture. Ancient examples can be found on the Basilica of San Vitale in Ravenna and on the Rotunda of Galerius in Thessaloniki. Architectural-element precursors derive from Byzantine architecture and Romanesque architecture, such as at Durham Cathedral, where arches transmit the lateral thrust of the stone vault over the aisles, hidden under the gallery roof. Early designs, such as at Chartres Cathedral (ca. Later architects refined the design, narrowing the flyers, as seen at Amiens Cathedral, Le Mans Cathedral, and Beauvais Cathedral. Late Gothic buildings featured flying buttresses with flyers decorated with crockets and sculpted figures set in aedicules.
Reader's Guide
The flying buttress allowed outer walls to be less massive and heavy, reducing wall surface and enabling larger windows, often glazed with stained glass. Vertical mass was concentrated onto external buttresses. The system is a two-part composite: a semi-arch extending to a massive pier, providing most load-bearing capacity of a traditional buttress while being lighter and more cost-effective. In Gothic churches, two arched flyers were often applied: the lower resisted lateral thrust of the vault, the upper resisted wind-loading on the roof. Vertical buttresses were capped with pinnacles to provide additional vertical-load support. The Renaissance eschewed flying buttresses in favor of thick-wall construction, but the design was revived in the early 20th century by Canadian engineer William P. Anderson for lighthouses. The flying buttress became a defining factor of medieval Gothic architecture, contributing to open space and light in cathedrals, and creating a sense of coherence and continuity between interior and exterior.
Did You Know?
- The flying buttress is not in contact with the wall at ground level, unlike a traditional buttress.
- Ancient examples of the flying buttress can be found on the Basilica of San Vitale in Ravenna and the Rotunda of Galerius in Thessaloniki.
- In the early 20th century, the flying-buttress design was revived by Canadian engineer William P. Anderson to build lighthouses.
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