Japanese Wood for Temple Longevity
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What can centuries-old Japanese temples teach us about timber longevity? In this guest article, Architect and TU Delft lecturer in Architectural Engineering and Technology, Florian Eckardt, explores the remarkable longevity of Japan's ancient wooden temples through the lens of craftsmanship, timber species and design.
Last summer, I had the opportunity to fulfill an old wish: to take a trip to Japan and visit some of its oldest temples. Starting in Tokyo with its contemporary buildings and mostly rebuilt temples, we slowly went back in time, seeing some original temple buildings in the former capital Kyoto. We then travelled to the city with the oldest surviving timber buildings: Nara. On a very hot day, we visited two temple complexes. First Horyu-Ji, a compound with buildings dating back to the 7th century. After that, Todai-Ji, an enormous temple that houses a large Buddha statue, originally built in the same period, but rebuilt twice.
Horyu-Ji is beautiful and modest in scale, comprised of an East and a West section. The West part consists of a 21m high main hall (the Kondo), and a five-story 32.5m high pagoda (called Goju no To) surrounded by a rectangular covered corridor (the Kairo). The pagoda cannot be climbed; its stories with slightly curved tiled roofs are decorative. The main hall, which one enters after climbing the stairs of a stone base, has a double first-story roof and above that another steeper second-story roof. While we were there, craftsmen were carrying out some repairs on a window shutter. It recalled the famous 20th-century renovation of Horyu-Ji that was carried out from 1934 on by the Nishioka family of master carpenters.
From there, we continued to the large temple of Todai-Ji, also in Nara. After an extended bus ride we reached the city center, with the museum and various temple complexes. We were welcomed by groups of tame deer that roamed around freely there, engaging with visitors who liked them but were a bit nervous about their antlers. We entered this complex through the Great South gate called Nandai Mon, a large structure with a double tiled roof carried by six rows of detailed brackets that frame the view of the enormous main hall (Daibutsuden) beyond, home to a 16m high bronze seated Buddha. The brackets are unique for the Great Buddha Style that the south gate and the Daibutsuden were rebuilt in. This building method was imported from the south of China, allowing for a fast assembly without the need for scaffolding thanks to the large tie-beams that penetrate from interior to exterior.
After our trip, I remained fascinated by the question of what gave these structures their incredible longevity. The answer is multifaceted, and it is different for both temples.
First, the temples were created on sites with geomantic properties considered ideal for longevity by Chinese and Japanese temple builders. In the case of Horju-Ji, with a stream to the east, a lake to the south, a wide road to the west, and a mountain to the north. What also contributes to that is the thinking in compounds rather than in buildings: walled ensembles with isolated buildings, so the sun can reach most parts of the structure and keep it dry with no shadows in the way.
The difference between the two temples begins with the trees used. Horyu-Ji was created in a period when Japan still had an abundance of ancient Hinoki forests. Hinoki (Japanese Cypress) is a strong, light tree with superb wood qualities, said to gain stability and resistance over time. It has a fine straight grain, a high resin content and is naturally resistant to rot and insects. At that period, it was possible to select enormous old-growth trees and build the entire structure from Hinoki. After carefully felling the trees, a prayer would be offered to preserve them in their new life within the building. As Horyu-Ji is of a modest size, many of its parts are made of pure Hinoki. The central pillar or Shinbashira of the pagoda, a relatively flexible post not rigidly fixed to its base, was made of a 500-year-old Hinoki trunk. In the Kondo, there are solid Hinoki door panels of a meter wide, that were carefully crafted and show narrow growth rings. Since four columns came out of one trunk, avoiding the heart of the tree, the trees used for that must have been giant. The pillars also show a clear entasis (curve in the profile) which is also quite unique for that period. The carpenters were able to create tight-fitting mortise and tenon joints using hardly any nails and always the same type of wood, so the building acts as a single entity against earthquakes. During an earthquake, these joints act as shock absorbers and stresses are distributed equally throughout the structure. At Horyu-Ji, the elegant Hinoki brackets are directly connected to solid columns. So, the combination of great craftmanship and one strong, flexible wood type that can be worked precisely is the key to its durability. During the renovation, master carpenter Tsunekazu Nishioka discovered that some trees used for the Pagoda were more than 1000 years old when felled, well in advance of being used. They were all from the Yoshino region, just south of Nara, and they were positioned according to their origin and growth form as well: twisted trunks counteracting each other, west-facing trees on the west side, and east-facing ones on the east side of the structure.
Moving on to Todai-Ji, first, it is of a different scale. As it houses a huge Buddha statue and was built to express power as a religious center, it measures 57 x 50 m and is 49m high, and originally was even wider, and built in a different style called Wayo style. It has a heavy tiled roof carried by 84 sizable 20m high columns.
For its rebuilding after arson in the 12th and again in the 16th century, a mixture of wood species was utilized. The availability of Hinoki had diminished over the centuries and Japan had been partially deforested. So Japanese Cedar (Sugi) and Japanese Pine were used besides Hinoki. This was also done for practical reasons: the project size alone required wood with a suitable strength-weight ratio and easy to work in large sizes, as well as for differentiation: in some areas it had to be flexible, in others strong, in others light. The scale of the project also required assembled rather than solid timber components. The main columns, for example, have a diameter of more than a meter and are made of Hinoki segments, as one can see from the outside. Large roof beams are made of Sugi, and compressive support structures of Japanese Pine. The beams are connected to the columns by a penetrating-tie beam connection, and therefore the columns can span multiple stories. Beams and brackets in the Horyu-Ji in comparison were placed on top of the columns (head-tie).
In all, the main hall of Todai-Ji acts as a hybrid system, a stack of laterally free parts carrying a heavy weight. In case of an earthquake, shocks are absorbed by the mass, and the energy is dissipated through the joints of a multilayered bracket system to the columns.
In conclusion, different principles at work, and different wood species, but all geared towards a maximum lifespan for these temples. The answer to their longevity lies in bringing together a superb wood quality and excellent craftmanship, but also in a design that is appropriate to the materials uses and the scale of each building.
Florian Eckardt, 16-07-26 with thanks to Jonas Stappers.