How Do Flying Buttresses Work?      

The Gothic Cathedral of Notre-Dame at Chartres

Hayla May

The train ride to Chartres was excruciatingly long and, simultaneously, too short for comfort. It was our group’s first full day in France so there were plenty moments of sporadic chatter to break my nervous internal preparation. When I felt that we were close to the town I was rubbernecking to see it. Finally, the spires broke over the green countryside and it turned to reveal itself: the Cathedral of Chartres. The monumental structure stood on the hilltop with a formidable presence that could be felt even out of view. Our group unloaded and made our way halfway up the hill where I was able to absorb the details of the architecture.

Cathedral of Chartres, view of North and West portals. Begun 1194. (Photo: Hayla May)

We approached from the West entrance and I wasn’t prepared for the Rose window or the intricacy of the façade surrounding it. I had been so entrenched in studying the support system and buttressing that I hadn’t paid much regard to the rest of the building. Seeing it with my own eyes made me understand how the design interplayed with the rest of the Cathedral, and how it balanced with the Choir on the East end. After talking about the tympanum and jamb figures, we made our way to the flying buttresses on the South side.

Chartres Cathedral, view of buttresses from the South, begun 1194. (Photo: Camryn Perry)

There are of course two basic types of buttresses: those that fly and those that don’t. The non-flyers are like columns that rest right up against the building to support the vaulting of the ceiling. Medieval Cathedrals, however, would have two aisles on either side of the ribbed vault, so the architects had to find a way to take the outward thrust of the vaults and extend it over these side aisles so the interior remained open. The result was flying buttresses and they became a standard feature of Cathedrals of the time, as the famous architect Viollet-le-Duc discussed in the 19^th century.  

The buttresses that I discussed had three registers of flyers that stretched from the buttress on the exterior of the side aisle to the nave walls. Alan Borg and Robert Mark explore how the bottom two were part of the original design, and the upper was added later; we know this because it’s much thinner and more horizontal, and placed where it wouldn’t actually give much support to the vault. We speculate that it was added as part of a wide-spread practice of counteracting windshield against the building (especially being that the structure extends well into heights where wind speed is much more powerful).

Several things struck me when I finally saw the Cathedral in the flesh. Its monumentality of course would throw anyone, but having studied its formative years which were slightly under a century ago, I felt especially in awe about its resilience. Secondly, I had seen photographs of the buttressing, but didn’t understand until I got there how rectilinear they would appear from a viewer’s grounded standpoint. I had been studying the Cathedral from the elevated flying arches and barrel vaults so the natural point of view was fascinating.

The most significant realization however was the synthesis of architectural elements. Bill Clark discusses in Medieval Cathedrals that preceding the Gothic era, buildings were characterized as Romanesque—which emphasized repeating volumetric units that added to a whole. Gothic replaced this so that these units were interdependent of each other and contributed to a unified, consolidated whole. I knew this was the case, but I didn’t realize how it had such minute and immense applications. The choir is an excellent example of this.

Chartres Cathedral, view of the radiating chapels and choir, c 1225-1260. (Photo: Hayla May)

The pointed arches of the lancet windows meet with the buttressing on either side of them. The repeating circular shapes above them are echoed underneath the balustrade, which in turn is repeated at the upper register. The flying buttresses that extend from the radiating chapels make the building appear to undulate (if a term so connotative of fluidity could be prescribed to such a place). This comradery of stonework is what captivated me the most.

It felt powerful presenting in front of such a feat. I felt that in laying eyes on it I had some type of ownership of it. I never would have found the architectural nuances I did if I hadn’t visited, nor would they have blown me away as they did. I only wish I could have spent another month there.

Chartres Cathedral, March 16, 2018: Hayla by the West portal. (Photo: Melissa Dunn)

Sources Consulted

Allthemed Docs. “BBC How to Build a Cathedral.” YouTube Video, 58:18 minutes. (October 25, 2017) https://www.youtube.com/watch?v=TrAoqIsbD9M (accessed 5 March 2018)

Borg, Alan and Robert Mark. “Chartres Cathedral: A Reinterpretation of Its Structure.” Art Bulletin, Vol. 53:3. (1973): 367-372

Clark, William. Medieval Cathedrals. Westport, 2006

Clark, William and Mark, Robert. “Gothic Structural Experimentation.” Scientific American, vol. 251 no. 5 (November 1984): 176

Fitchen, John. “Vault Construction and Scaffolding” in Chartres Cathedral, edited by Robert Branner (New York: 1969): 124-125

Gold, Rob. “Explaining the Flying Buttresses.” YouTube Video, 1:24 minutes. (September 12, 2010) https://www.youtube.com/watch?v=dhB0VhuKCUs (accessed 1 March 2018)

Macaulay, David. Cathedral: The Story of Its Construction. Boston, 1973

Murray, Stephen and Andrew Tallon. “Mapping Gothic France.” Columbia University and Vassar College. http://mappinggothic.org/about (accessed February 25, 2018)

Open University. "Flying Buttresses at Chartres." 02:40 minutes. (November 5, 2009) http://podcast.open.ac.uk/oulearn/mathematics-and-statistics/podcast-mst209-arch-never-sleeps#!d921babd20 (accessed March 10)

Raunch, Thomas M., and Robert Mark. “Model Study of Buttressing the Piers in Chartres Cathedral.” Gesta, vol. 6 (1967): 21-24

Viollet-le-Duc, E. E. “Flying Buttresses” in Chartres Cathedral, edited by Robert Branner. (New York: 1969): 121-122