‘Like a game of black-belt level Jenga’: inside the ancient art of Japanese carpentry

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Do you know your ant’s head from your shell mouth? Or your cogged lap from your scarfed gooseneck? These are just some of the mind-boggling array of timber jointing techniques on display in a new exhibition spotlighting the meticulous craft of Japanese carpentry. The basement gallery of London’s Japan House has been transformed into a woody wonder world of chisels and saws, mortises and tenons, and brackets of infinite intricacy, alongside traditional clay plastering, shoji paper screen making and tatami mat weaving. It is a dazzling display of the phenomenal skills behind centuries of timber architecture and joinery, celebrating elite master carpenters with the spiritual reverence of a high priesthood.

“In Japan we have a deep respect for our forests,” says curator Nishiyama Marcelo, who heads up the team at the Takenaka Carpentry Tools Museum in Kobe, a temple to the history of Japanese joinery. “If a carpenter uses a 1,000-year-old tree, they must be prepared to take on more than 1,000 years of responsibility for the building that they create.”

It is a momentous duty, and one we should heed. As debates around the embodied carbon of the built environment dominate the construction industry, there could be no more timely exhibition to remind us of the importance of designing with longevity, care and repair in mind. Numerous specialist tools have been shipped over from the Kobe museum, along with a team of master carpenters who have built a remarkable series of structures in the gallery, replicating parts of buildings that have lasted for hundreds of years in the face of wind, rain, snow and earthquakes.

Tools of the trade … a display of hand planes.

Dominating the room is a 1:2 scale reconstruction of a section of the Toindo hall at the temple of Yakushi-ji in Nara, built in the Kamakura period (1185-1333). It shows how the roof’s deep eaves are supported by delicately curved parallel rafters, along with a coffered ceiling of cleverly intersecting horizontal beams, all held together by invisible joints. Key to supporting the immense weight of the tiled, tiered rooftops are the brackets, or kumimono, each made up of a fiendishly complex cat’s cradle of masu (bearing blocks) and hijiki (bracket arms), stacked in four directions. A table nearby shows the more than 50 hand-carved wooden pieces that go into assembling just one of these brackets, along with a 3D animation showing how the bits all fit together. It looks like a game of black-belt-level Jenga.

It may seem like a decorative flight of fancy, a bravura exercise in complex carpentry, simply to embellish the corners of the temple, but these brackets serve a crucial seismic purpose too. “We have a lot of earthquakes in Japan,” says Nishiyama. “The reason these temples have survived so long is because of these intricate timber joints, which allow the structural members to slide past each other, as well as distributing the load.” When the Great Hanshin earthquake struck Kobe in 1995, with devastating impact on the Kansai region, the Yakushi-ji temple emerged unscathed. Indeed, it had survived many earthquakes since its first construction in the seventh century.

Taking a similar approach to the flexible bracket joints, the timber columns of temples and shrines usually sit on raised stone bases. This not only prevents the wood from getting damp and rotting, but allows lateral movement in the event of seismic activity. A nearby display shows how the bottoms of the columns are carefully sculpted to fit into the natural curves of the uneven stone bases, using a contour gauge in a process known as hikari-tsuke. The level of hand-tooled precision looks like a devotional religious act in itself, and there is a spiritual reverence for these natural materials from the start. The woodsmen even seek permission from the mountain spirit deities, or kami, when felling the trees in the forest.

A selection of sashimono kigumi wood joints.

The reconstruction and maintenance of these ancient Shinto shrines and Buddhist temples is the exclusive work of domiya daiku, or temple carpenters, who enjoy a rarefied status as keepers of architectural heritage that spans more than a millennium. One of the greatest such 20th-century figures was Nishioka Tsunekazu, nicknamed oni, or the devil, for his exacting approach. His meticulous structural drawings, carved into wooden boards, are shown in the exhibition, combining elevations, cross-sections and 45-degree diagonal views at once. They hang alongside racks of templates used to cut the different components, which dangle from pegs like tailors’ manilla pattern cards.

Nishioka laid out key principles, advising that wood for temple construction should be taken from a single mountain, and specifying that trees grown on higher slopes should be used for for structural elements such as beams and pillars, while those in the lower valleys are better for finishing materials. Knowing which trees to use for which purposes, says Nishiyama, showing off a display of different kinds of cypress, pine, chestnut, and bamboo logs, is just as important as knowing how to put them together.

Alongside the domiya daiku we are introduced to the profane world of the sukiya daiku, or teahouse and residential carpenters, known for their more lightweight, rustic style. While the carpenters of temples and shrines revelled in the structural acrobatics of massive beams and weighty roofs, the traditional teahouse is an essay in delicacy and economy of means. For the exhibition, the team has re-created Sa-an, a famous teahouse built in 1742 at the Zen monastery of Daitoku-ji in Kyoto. But here it has been stripped of its plaster walls to reveal the skeletal structural workings. The aesthetic of sukiya gives the impression of rustic simplicity, often using unprocessed round logs stacked in a childlike diagram of a house. But as the exhibition reveals, the intersection of round logs, using an invisible jointing technique known as neji-gumi, is “the pinnacle of log craftsmanship”. Once assembled, it is almost impossible to discern how the pieces fit together. A breakdown of the component pieces, along with another animation, reveals how this miraculous carpentry conjuring trick is done. Forget black belt, this is 10th dan, sensei-level stuff.

Craft of Carpentry exhibition is at Japan House London.

There’s plenty more to discover, from the secrets of exquisite kumiko latticework screens to the wonders of sashimono joinery, used to make boxes and furniture, along with a hands-on display upstairs where you can have a go at assembling some of these 3D puzzle-like joints for yourself. But if there’s one thing missing, it is any mention of how these techniques could be of broader relevance today. Nishiyama admits that the work on show comes from an exclusive niche, reserved for luxury commissions, with something like the teahouse on display costing “around 10 times as much to build as a regular house” due to the specialist manual craftsmanship involved. It seems that the contemporary master carpenter’s skills are reserved for billionaires’ garden follies, or the conservation of priceless heritage.

Yet there are crucial lessons that the modern construction industry could learn from. The sophistication of Japan’s carpentry culture was born of necessity: the country’s lack of iron meant that jointing techniques had to be developed that did not rely on nails. We are moving towards a time when design for disassembly and repair has become ever more desirable, and necessary, than our bulldoze-and-rebuild mindset. Resource scarcity is a very real prospect. These centuries-old techniques, updated with today’s technology – with components milled using computer-controlled machinery, not just hand tools – could well hold some answers for a low-carbon, long-life, reconfigurable future.