Buttresses and the Flying Buttress

You Think All Buttresses Look Alike?

stone dwelling with small windows, shutters, arched buttress to larger building
Medieval Stone Houses. Dan Herrick//Getty Images

A buttress is a structure built to support or reinforce the height of a masonry wall. Buttresses counteract side thrust (lateral force), preventing a wall from bulging and buckling by pushing against it, transferring the force to the ground. Buttresses can be built close to an exterior wall or built away from a wall — the thickness and height of the wall and weight of the roof may determine the design of a buttress. Owners of stone homes, no matter the height, have realized the engineering advantages and architectural beauty of the flying buttress. See how they work and how they've evolved by browsing this photo gallery of buttress examples.

Flying Buttresses at Notre Dame Cathedral, Paris

apse with flying buttresses
French Gothic Notre Dame Cathedral in Paris. John Elk III/Getty Images

Buildings made of stone are structurally very heavy. Even a wooden roof atop a tall building might add too much weight for the walls to support. One solution is to make the walls very thick at street-level, but this system becomes ridiculous if you want a very tall, stone structure.

The Dictionary of Architecture and Construction defines buttress as an "exterior mass of masonry set at an angle to or bonded into a wall which it strengthens or supports." Before the invention of steel frame construction, exterior stone walls were structurally load bearing — good at compression but not so good with tension forces. The "buttresses often absorb lateral thrusts from roof vaults," the dictionary explains.

Buttresses are often associated with the great cathedrals of Europe, but before Christianity the ancient Romans built great amphitheatres that sat thousands of people. Height for the seating was achieved with arches and buttresses.

One of the greatest innovations of the Gothic era was the "flying buttress" system of structural support. Attaching to the external walls, arched stone was connected to huge buttresses built away from the wall as seen on the French Gothic Notre Dame Cathedral in Paris. This system allowed builders to construct soaring cathedrals with massive interior spaces, while allowing walls to exhibit expansive stained glass windows. Elaborate pinnacles added weight, which allowed the buttresses to carry even more lateral thrust from the exterior wall.

The Butt of It All

close-up look of the flying buttress, with arched brace from an external wall to the wall of a church
English Gothic Flying Buttress, 1300s, York, England. mikeuk/Getty Images

The noun buttress comes from the verb to butt. When you observe a butting action, like animals that butt heads, you see a thrusting force being imposed. In fact, our word for buttress comes from butten, which means to drive or thrust. So, the noun buttress comes from the verb of the same name. To buttress mean to support or prop up with a buttress, which pushes against the thing needing support.

A similar word has a different source. Abutments are the supporting towers on either side of an arch bridge, like the Bixby Bridge in Big Sur, California. Notice that there is only one "t" in noun abutment, which comes from the verb "abut," which means "to join end to end."

The French Basilica of St. Magdalene, 1100, Vezelay

large, stone structure with lower walls with buttresses supporting upper walls
The Basilica of St. Magdalene, Vezelay, Yonne, Burgundy, France. Julian Elliott/Getty Images

 The medieval French town of Vezelay in Burgundy lays claim to a striking example of Romanesque architecture — the pilgrimage church Basilique Ste.Marie-Madeleine, built around the year 1100.

Hundreds of years before Gothic buttresses "began to fly,"  medieval architects experimented with creating soaring, God-like interiors by using a series of arches and vaults. Professor Talbot Hamlin notes that "the need for withstanding the thrusts of the vaults, and the desire to avoid a wasteful use of stone, led to the development of exterior buttresses — that is, thicker portions of the wall, placed where they could give it extra stability."

Professor Hamlin goes on to explain how Romanesque architects experimented with engineering the buttress, "sometimes making it like an engaged column, sometimes as a projecting strip like a pilaster; and only gradually did they come to realize that its depth and not its width was the important element....."

The Vezelay Church is a UNESCO World Heritage site, notable as "a masterpiece of Burgundian Romanesque art and architecture."

Condom Cathedral, 1500, Southern France

large, stone church with square tower soaring over elongated buttressed wall
Condom Cathedral c. 1530, France. Iñigo Fdz de Pinedo/Getty Images

The flying buttress may be the most well-known, but throughout the history of architecture, builders have designed different engineering methods to buttress a masonry wall. The Penguin Dictionary of Architecture sites these types of buttresses: angle; clasping; diagonal; flying; lateral; pier; and setback.

Why so many kinds of buttresses? Architecture is derivative, building on the successes of experimentation throughout time.

Compared with the earlier Basilique Ste. Marie-Madeleine, the French pilgrimage church in Condom, Gers Midi-Pyrénées is built with more refined and slender buttresses. It would not be long before Italian architects would extend the buttress away from the wall, as Andrea Palladio did at San Giorgio Maggiore.

San Giorgio Maggiore, 1610, Italy

domed brick church with buttressed walls
Andrea Palladio's 16th century Church of San Giorgio Maggiore, Venice, Italy. Dan Kitwood/Getty Images (cropped)

Renaissance architect Andrea Palladio became famous for bringing Classical Greek and Roman architectural designs to a new century. His Venice, Italy church San Giorgio Maggiore also exhibits the evolving buttress, now more slender and extended from the wall compared with the churches at Vezelay and Condom in France.

Saint Pierre, Chartres

Flying butresses on a stone church abbey, large stained glass windows, smaller surrounding stone structures with red roofs
Saint Pierre in Chartres, France. Julian Elliott/Getty Images

Built between the 11th and 14th centuries, L'église Saint-Pierre in Chartres, France, is another fine example of the Gothic flying buttress. Like the more well-known Chartres Cathedral and Notre Dame de Paris, Saint Pierre is a medieval structure built and rebuilt throughout the centuries. By the 19th century, these Gothic cathedrals became part of the literature, art, and popular culture of the day. French author Victor Hugo used the architecture of the church in his famous 1831 novel The Hunchback of Notre-Dame:


"At the moment when his thought was thus fixed upon the priest, while the daybreak was whitening the flying buttresses, he perceived on the highest story of Notre-Dame, at the angle formed by the external balustrade as it makes the turn of the chancel, a figure walking."

National Cathedral, 1990, Washington, D.C.

multi-story stone building with buttresses along the exterior walls
Gothic Revival Washington National Cathedral, 1990, Washington, D.C. Harvey Meston/Getty Images (cropped)

Even when construction methods and materials advanced to make the buttress unnecessary, the Gothic look of the Christian church was ingrained in society. The Gothic Revival house style flourished from 1840 until 1880, but reviving Gothic designs never became old in sacred architecture. Built between 1907 and 1990, the Cathedral Church of Saint Peter and Saint Paul is more commonly called the Washington National Cathedral. Along with buttresses, other Gothic features include over 100 gargoyles and over 200 stained glass windows.

Liverpool Metropolitan Cathedral, 1967, England

aerial view of round church, shiny roof with beams from the roof tip down below the roofline to the ground, looking like buttresses
Liverpool Metropolitan Cathedral of Christ the King, 1967, United Kingdom. David Goddard/Getty Images (cropped)

The buttress has evolved from an engineering necessity to an architectural design element. The buttress-like elements seen on the Metropolitan Cathedral of Christ the King in Liverpool are certainly not necessary to hold up the structure. The flying buttress has become a design choice, as an historic homage to the great Gothic cathedral experiments.

Architecture such as this Roman Catholic church points out the difficulty of assigning architectural style to a building — is this building from the 1960s an example of modern architecture or, with its homage to the buttress, is it Gothic Revival?

Adobe Mission, 1816, New Mexico

windowless adobe structure supported by massive buttresses
St. Francis of Assisi Mission Church in Ranchos de Taos, New Mexico. Robert Alexander/Getty Images (cropped)

In architecture, engineering and art come together. How can this building stand up? What do I have to do to make a stable structure? Can engineering be beautiful?

These questions asked by today's architects are the same puzzles explored by builders and designers of the past. The buttress is a good example of solving an engineering problem with evolving beautiful design.

St. Francis of Assisi Mission Church in Ranchos de Taos, New Mexico is constructed of native adobe and designed in the tradition of the Spanish colonials and native Americans. Nevertheless, the thick adobe walls are braced with buttresses — not Gothic-looking at all, but beehive shaped. Unlike parishoners of the French Gothic or Gothic Revival churches, volunteers in Taos gather each June to resurface the adobe with a mud and straw mixture.

Burj Khalifa, 2010, United Arab Emirates

low angle detail of modern skyscraper tower
Burj Khalifa Tower, Dubai, United Arab Emirates. Holger Leue/Getty Images (cropped)

Buttresses remain an important structural element in modern buildings. For years the Burj Khalifa in Dubai has been the highest skyscraper in the world. How do those walls stand? An innovative system of Y-shaped buttresses allowed designers to build a skyscraper that soared to its record-breaking height. Skidmore, Owings & Merrill LLP (SOM), who also designed One World Trade Center in Lower Manhattan, took on the engineering challenge in Dubai. "Each wing, with its own high-performance concrete core and perimeter columns, buttresses the others via a six-sided central core, or hexagonal hub," SOM described its Y-shaped plan. "The result is a tower that is extremely stiff torsionally."

 Architects and engineers have always wanted to build the highest building in the world. The ancient art of buttressing has always helped make that happen, in every century of architectural history.

Sources

  • Harris, Cyril M. ed. Dictionary of Architecture and Construction. McGraw-Hill, 1975, p. 78
  • The Penguin Dictionary of Architecture, Third Edition, 1980, p. 55
  • Architecture through the Ages by Professor Talbot Hamlin, FAIA, Putnam, Revised 1953, pp. 263-264
  • Washington National Cathedral. Facts and Figures, https://cathedral.org/architecture/facts-figures/
  • Skidmore, Owings & Merrill LLP (SOM). Burj Khalifa – Structural Engineering. https://www.som.com/projects/burj_khalifa__structural_engineering