T
he use of wood as a structural material in building shelters dates back to the dawning of man. Seeking refuge from the elements and predators, early man used whatever he could find available for protective cover. The environment naturally dictated the means: caves, dugouts, snow, straw, twigs, reeds, mud, stone and wood. The first rudimentary hut was probably invented by pulling down and securing a tree branch in full foliage.
Man had settled in many areas of the globe. Some were high plateaus with little vegetation, others flat grass lands, or arctic snow fields, rocky mountain terrain, or lush forested land. It is in these forests, or in their proximity, that the first usage of wood timber would evolve through environmental adaptation and be applied to structural concepts.
The first early elaborations of the use of timber in quadrangular concepts can be traced back to Asia Minor in 7000 BC (circa). Although records are sketchy, it is believed that, before the Christian era, common techniques evolved simultaneously in various parts of the world with little or no cultural crossover.
Still far from tongue and groove techniques, cross pieces were often tied (tethered) together with rope. Initially conceived to provide shelter, the use of these rudimentary structures was first and foremost to support a roof. To this day, this fundamental principal is seen in all traditional timber frame structures; the roof being an intrinsic part of the frame. In 2000 BC (circa), post and beams were assembled in apposition, disassociated from the walls which were usually made of stone. They would carry a flat roof over which were laid a bed of reeds, covered in mud and let to bake in the sun.
By the year 900 BC (circa), the master engineers in Greece had discovered and applied triangulation to framing techniques. They invented the two-slopped roof. With this shift in conceptual designing, came the notion of encasement of posts and beams.
The idea of the bent appeared at approximately 800 to 700 BC. It would develop over the next 300 years. The Demeter temple in Selinorte (IV BC circa) is a good example of the advancements achieved in timber framing techniques of this era.
More spacious temples called for more innovations, responding to the needs of growing populations in major cities and communities. The improvements on the concept of the bent allowed for the removal of the main crosspiece, thus lightening the load and overall weight of the frame, eliminating interior columns and strengthening the structure. The knowledge of applied geometry allowed to diffuse the forces by distributing the weight equally to the supporting outer posts. This allowed for the expansion in size and interior volume of the temples, thus adding to the grandeur and prestige of these dwellings for the gods.
There would be a great leap in the techniques and concepts from IV to II BC as master carpenters were hired from Athens to Alexandria to conceive and build great halls and warehouses to meet the growing needs of trade and commerce. Tongue and groove joinery was now being used with a higher degree of complexity.
From the 4th to the 6th century AD, intricate geometrical concepts would give rise to the first great basilicas and cathedrals of the Middle East and would eventually spread to the far reaches of Western Europe, as Christian faith swept across the lands. Innovative applications produced intricate arches and rounded shapes not yet seen in timber framing designs.
Very quickly now, timber framing concepts would evolve across all of Asia, Europe, Africa and even in the yet undiscovered Americas.
Timber Framing In The Orient
Timber Framing in China can be traced back to the Yang-Shou civilization, 6000 to 3000 B.C. Already at this time, structures were of an interesting complexity and the knowledge of tongue and groove joinery well demonstrated.
Very early on, the Chinese master carpenters were to develop the use of tongue and groove joinery, while the structural designs, using quadrangular and simple triangular concepts, would evolve at a slower rate. More intricate tongue and groove techniques can be found in structures dating from 1600 to 1100 B.C. These techniques would again rapidly evolve between 1100 and 770 B.C. with the introduction of iron tools. From 770 to 221 B.C., the Chinese had developed a very high proficiency in tongue and groove, lifting and raising techniques.
It is interesting to note that between the years 206 and 220 AD, the use of longitudinal frames was abandoned to be replaced by transversal frames.
From this point on, timber framing techniques in China would have a considerable influence on other Asian countries, notably Japan. The Japanese master carpenters applied intricate triangulation concepts in the building of complex, multi-level structures between 618 and 907 AD. Here, lie the roots of traditional timber framing in the Orient.
Traditional Timber Framing In France
History traces back to the XIth century the roots of traditional timber framing in France. Called charpentes des combles (attic frames), they were the most widely used forms of structural framing next to stone masonry, and their technology was to evolve continuously for more than seven hundred years.
France's geographical position gave it a favorable edge in benefiting through cultural exchange. France is seated on the dividing line between two great currents of civilization: the Mediterranean to the south, and the Nordic, to the north. Up until the XIth century, France had been coming into its own, adapting through trade and cultural influences pouring in from Belgium in the north, Germany in the north-east, Italy in the south-east, Britain in the north-east. The Vikings and the Norse left their mark in the north. Arabic influences would filter through from the south. Nonetheless, historical research reveals a uniqueness in the technology and the design details of XI to XVIII century buildings in France that is distinctively French, proving that these works were conceived and executed by the French, and suggesting that outside influences were relatively negligible. For instance, in the XII century, Scandinavians were building small scale, hard wood churches, while in France, master carpenters were erecting cathedrals of the type of Notre-Dame de Paris. There is a wide gap of knowledge between both worlds. Although the Scandinavians have contributed to the origins of timber framing in France, they have not been able to achieve the same results in their homeland.
Timber framing in France has evolved through four great periods of art: The Roman, The Gothic, The Renaissance and The Classic. Researchers have divided timber frame types into four major groups:
• Charpente à chevrons formant ferme (common rafters forming a bent)
• Charpente à ferme et pannes (bent and purlins)
• Charpente vouté (arched or vaulted)
• Charpente à la Philibert Delorme
Charpente à chevrons formant ferme (common rafters forming a bent)
This type of timber frame was the most widely used in the north of France. Early structures used a mid-section assembly technique with parallel verges. It led to new concepts in raising techniques. It would eventually evolve to exclusively use tongue and groove joinery. As techniques were refined over the years, this concept would lead to the design of great gothic structures that would withstand the test of time and technology. Roof angles reaching 100% in the XI century, extended to 150% and 200% by the XIII century. This type of timber framing was widely used well into the XVIII century, resisting influences from even the Renaissance period.
One of the main reasons why the Charpente à chevrons formant ferme came to be was that it offered a flexibility and an adaptability to environmental and economic restrictions. Its technology allowed for the use of adapted building materials directly derived from the surrounding forests, with variable dimensions and qualities of wood, using all parts of the tree, including wood scraps and recycled timber, thus limiting waste in difficult economical times. Irregular shapes of wood pieces were not a problem for the master carpenters who used the trait carré, sometimes referred to as the "scribe" method, a squaring technique using the centre line forming the axis of the piece of lumber for geometrical alignment and transcribing onto a ground plan the exact dimensions of the piece to be cut using a line and plumb bob.
This type of timber framing underwent a constant evolution in its technology and applications into the XV century. It reached a plateau through the XVI and XVII, then somewhat declined in XVIII. As attics were being built smaller, this type of frame was eventually abandoned in monumental architecture, while it continued to be used in areas were adapted materials were available.
Charpente à ferme et pannes (bent and purlins)
By the XV century, the introduction of the Charpente à ferme et pannes was to foster a new era in timber framing technology. It would co-exist along with the charpente à chevrons formant ferme and would lead to many innovations, coinciding with an economic uplifting and the beginning of a wealthy period in the history of France.
This concept was to become the preferred style for building bents. The design helped strengthen the crosspieces, allowed to build multiple levels and portico bents, while permitting the use of irregular shaped timber.
CCharpente vouté (arched or vaulted)
Vaulted or arched frames (also called charpente lambrissée) were in use as early as XI forming the roof of roman period basilicas. Up until a few decades ago, some of these structures built in XI and XII were still standing. These vaulted frames were made of stone or wood, although wood was often preferred because it was less expensive. In some churches, both were used; stone for the choeur and paid for by the clergy, wood for the nave and paid for by the people. It was thought that these frames were the work of shipbuilders because of their shape resembling the overturned hull of a wooden ship. Research totally credits timber framers, not shipbuilders, for their design and engineering.
Charpente à la Philibert Delorme
A word must be said about this important XVI century figure in the history of timber framing. A mason by trade, he spent many years in Italy where he studied Antique Architecture and mastered the trade of timber framing. Upon returning to France, he was appointed Inspecteurs de fortifications de Bretagne and later made Contrôleur de bâtiments du Roi. His contribution to timber framing was one of passion and dedication for the trade. His knowledge and respect of architecture reflected well upon the pride and achievements of the French. His observations led to the invention of a unique style of framing regarded as the first true expression of an engineer's frame, and to the creation of laminates.
XVIII TO XX
Very little research exists on timber frames dating from XVIII to our day. Although, we do know that the trade is still practiced today by a small group of master carpenters who have learned their skills in the traditional trade schools of France. These schools train their students in the centuries old tradition of the Order of Les Compagnons du Devoir, dedicated to the highest knowledge and finest execution of manual building trades.
Their knowledge of the craft, expertise in designing and technical drawing, experience and skills in the shop and on the field, all contribute to their demand on major reconstruction or renovation projects, striking and reassembling jobs, historical conservation projects, and new, innovative building projects. The history books of the later two centuries might still need to be written. But rest assured that traditional timber framing is still being practiced today and kept alive thanks to the dedication and commitment of the masters, and to the growing number of people who share the same passion, love and respect for this art and science, its ethics and esthetics.
