The Flying Buttress

The flying buttresses of the apse at the Cathedral of Our Lady of Chartres.

A buttress is an architectural element which is built against or projects from a wall which serves to protect or reinforce said wall.  They are common on buildings of certain styles or eras where they counteract the lateral forces from roofs that lack necessary bracing.  In other words, they stop the roof from squashing the walls.

The odd-shaped "walls" that extend from the sides of this church in the
Philippines (building to right) are examples of regular buttresses.

The Durham Cathedral, properly the Cathedral Church of Christ, Blessed Mary the Virgin and St. Cuthbert of Durham, is in northeast England and is the seat of the Anglican Bishop of Durham.  The cathedral was built in 1093, and is considered one of the finest examples of Norman architecture.  It has been designated a UNESCO World Heritage Site.  The cathedral is notable for the flying buttresses over the aisles, which are precursors of the Gothic style of architecture even though the building is considered to be of Romanesque design.  Buttressing made it possible to build taller buildings and open up space.

The quadrant arches in Durham Cathedral carried the
lateral thrust of the stone vault over the aisles, where they
were supported by buttresses.  These were precursors
of the fully-fledged flying buttresses.

The main advantage, which spurred the development of flying buttresses, was that outer walls didn't need to be as massive since the buttresses would relieve them of the burden of the weight of the vault.  This allowed for the wall space to be reduced so windows could be larger and designed with stained glass.  The buttress thus was a vertical masonry block on the outside of the building with an arch that stood in the gap between the buttress and the wall (the "flying" part).  One of the earliest uses of flying buttresses, which still survives, is the Basilica of St. Remi in Reims, dated to circa 1170.

The buttresses at the apse of the Basilica of St. Remi.

These first flying buttresses were unnecessarily heavy, but that much buffering wasn't needed for the loads they were to bear.  Later architects designed them to be slimmer and more refined.

These flying buttresses at the Cathedral of Our Lady
of Amiens, built between 1220 - 1270, are much more
graceful and elegant.

As the Gothic style of architecture continued, the flying buttresses were often embellished with "crockets", as were furniture and metalwork made in the Gothic style.  These were hook-shaped decorative elements that were stylized leaves, flowers, or buds. Aedicules were also a common decorative element.  They were framing devices used to highlight the importance of its contents, and were set into the buttresses.

Crockets on the finials at Sint-Petrus-en-Pauluskerk
in Ostend, Belgium.

Another use for flying buttresses was as an emergency measure to shore up walls in danger of collapsing.  This would often be more practical than rebuilding a wall, especially if it was the only weak part of a building.  Later architects abandoned the use of flying buttresses in favor of thicker walls.

The south wall of Chaddesley Corbett Church, begun in
the 12th century, has an added flying buttress to support
a weaking wall of the south aisle, built in the 14th century.

Flying buttresses are a hallmark of Gothic architecture.  They allowed the construction of taller buildings with soaring interior space.  Since they allowed for bigger windows in the walls, more light could enter the building, making it less gloomy.  It was an innovation that led to the great cathedrals, and some of the most spectacular architecture extant today.

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Images courtesy of Wikipedia.

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