The Conservation and Transmission of Wooden Architecture

In December 2020, “Traditional skills, techniques and knowledge for the conservation and transmission of wooden architecture in Japan” was inscribed on UNESCO’s Representative List of the Intangible Cultural Heritage of Humanity.

Some seventy percent of the landmass of Japan is forested, and wood harvested from the forests has been used to make buildings since ancient times. Perhaps surprisingly, given wood’s susceptibility to rot and mold, many of the oldest wooden buildings still standing in Japan date back to the early eighth century, albeit not exactly in their original form.

Traditional wooden buildings with their all-timber pillars and beams, infill walls, thatched roofs, tatami mat flooring, paper screens and other such fragile features need regular repairs, renovation and, sometimes, rebuilding. Repairs and renovation are carried out primarily to eliminate the mold and other fungi that can build up indoors in Japan’s hot and humid climate, and to address other effects of wear and weathering. Sometimes, however, renovation or rebuilding is necessitated by the sort of natural disasters to which Japan’s wooden buildings are simultaneously vulnerable and resistant, such as earthquakes and typhoons, not to mention fire.

The main hall (foreground) at Horyu-ji temple, Nara PHOTO BY m-louis VIA FLICKR, CC BY-SA 2.0


The world’s oldest extant wooden building is the main hall at Horyu-ji in Nara, founded in 607. The temple burned to the ground following a lightning strike in 670 but was immediately reconstructed. Conservation work on the buildings of Horyu-ji in the subsequent 1,300 years is well documented and has entailed total or partial dismantlements, as well as many large-scale and lesser repairs. In 1949, during conservation work on the main hall, a fire broke out, destroying the surface of the supporting pillars and the building’s ancient murals. However, owing to the careful transmission of knowledge over the centuries, the pillars and beams were replaced with new wooden members that precisely matched their forebears. Structurally, the building today appears just as it always did.

The Carpenters

In December 2020, “Traditional skills, techniques and knowledge for the conservation and transmission of wooden architecture in Japan” was inscribed on UNESCO’s Representative List of the Intangible Cultural Heritage of Humanity. The designation covers seventeen categories of skills, techniques and knowledge related to wooden architecture recognized to be indispensable to preserving cultural assets, including such heretofore lesser heralded techniques as the harvesting of cypress bark and grasses for thatch, the tapping of urushi lacquer trees, and the production of tatami mats.

Conventionally, master craftsmen had trained apprentices as successors to transmit their knowledge of the traditional skills, but with industrialization and modernization beginning in the mid-nineteenth century, this process became increasingly more difficult, so preservation associations were formed. For example, the seventeen conservation techniques recently inscribed by UNESCO are preserved by fourteen different artisanal organizations, including the Japanese Association for Conservation of Architectural Monuments.

Repair and restoration work at the aforementioned Horyu-ji, at Yakushi-ji (both UNESCO World Heritage Sites) and at numerous other historic monuments of Nara was led in modern times by the master shrine and temple carpenter Nishioka Tsunekazu (1908–1995). Nishioka devoted his life to the maintenance of the buildings with whose care he was entrusted and to the transmission of knowledge handed down by his father and grandfather, who were also temple carpenters. Nishioka was insistent on using only the traditional carpentry techniques and tools.

Nishioka Tsunekazu (right), the master temple carpenter from a family of temple carpenters PHOTO BY THE JAPAN JOURNAL AT TAKENAKA CARPENTRY TOOLS MUSEUM


When we look upon traditional wooden buildings such as Horyu-ji and Yakushi-ji today, consideration of the skilled human engagement with them over the centuries leads us to understand that the structures themselves are in a sense alive—that we are viewing them at a once-in-a-lifetime moment in their complex and unpredictable journey of repair and renewal. 

Up on the Roof

At Kasuga Taisha in Nara, a Shikinen zotai is held once every twenty years, this being a ceremonial “periodic reconstruction” entailing the restoration of shrine buildings and the treasures, tools and instruments held therein. As a consequence of the regularity of this repair and renewal, the buildings of Kasuga Taisha are perfectly preserved in their original form.

The newly re-thatched roof of the Honden main sanctuary at Kasuga Taisha (2016). The sanctuary comprises four worship halls that enshrine the four major deities associated with the shrine. JAPAN JOURNAL PHOTO


The roofs of most of the thirty-one structures on the Kasuga Taisha grounds are thatched with cypress bark. During the latest Shikinen zotai, in 2016, the task of repairing the four roofs of the Honden main sanctuary was assigned to one Tanigami Nagateru and his company. Tanigami has inherited the rare set of skills needed to create all-natural thatched roofing using locally produced cypress bark. Thatching in this traditional way involves tightly binding sixty or more layers of cypress bark together and pinning them using bamboo nails. The art, according to Tanigami, is in achieving the correct curvature of the eaves.

With the aid of a model, carpenter Tanigami Nagateru explains the techniques used in the reconstruction of the cypress-bark-thatched roofs at Kasuga Taisha. JAPAN JOURNAL PHOTO


“Only the bark of the Japanese cypress has the necessary softness to achieve such a thatch,” according to Tanigami. “Imported cypress from China or Korea for example will not do. This bark thatch could last for thirty or forty years. The bark itself never withers.”

In some cases, conservation techniques have been handed down not through family businesses or regional artisanal associations but as a simple matter of survival within communities. In Shirakawago, Gifu Prefecture, the steep-sloping roofs of the houses are thatched with grass which traditionally was cultivated individually by the villagers in plots in the surrounding forests. The whole village would work together to strip and re-thatch each house in turn, as required, in an expression of community spirit known as yui.

Thatched houses at Shirakawago, Gifu Prefecture. Thatching methods and the shape of thatched roofs vary according to area, depending on climate. In Shirakawago, the snowfall is heavy in the winter, hence the steep-sloped thatch. PHOTO BY IQRemix VIA FLICKR, CC BY-SA 2.0


As the number of thatched houses has declined, so efforts to conserve the techniques of harvesting thatching materials and thatching itself have increased, and these efforts will be supported by their inscription on the UNESCO list. 

Thick Shirakawago thatch PHOTO BY mendhak VIA FLICKR, CC BY-SA 2.0


Amazake Chaya teahouse on the Old Tokaido Road close to Moto-Hakone, Kanagawa Prefecture. The teahouse, renovated in 2009, is notable for traditional features such as its thickly thatched roof and sakan plaster walls. JAPAN JOURNAL PHOTO


Traditional wooden buildings also often make use of kawara tiles, another building material with a limited lifespan. When repairing a tiled roof, the roofers determine how many of the old tiles can be reused and then integrate the newly baked tiles in a way that creates harmony while continuing to protect the structure from the elements. They also lay the tiles in a way that gives the edges of the eaves a slight upward curve, another specialized skill. 

The South Main Gate (Nandaimon) to Horyu-ji temple. The structure is protected and characterized by its kawara tiles. PHOTO BY m-louis VIA FLICKR, CC BY-SA 2.0


Kawara earthenware tiles are typically fashioned from age-old wooden molds using traditional tools. The preservation association is based in Nara, where the tiles are in evidence on all manner of buildings, not just shrines and temples.

Decoration and Color

Beyond the structural needs in the conservation of wooden buildings there are decorative considerations too, with UNESCO inscribing on the list of Intangible Cultural Heritage a number of techniques vital to the continued enjoyment of traditional wooden buildings in their “original” decorative form.

Toshogu in Nikko was built in 1617 (rebuilt in 1636) in honor of Tokugawa Ieyasu (1543–1616), one of the “three unifiers” of Japan and founder of the Tokugawa Shogunate. Elaborately decorated with brightly colored lacquer, gold leaf and thousands of exquisite wood carvings, the shrine buildings are an extraordinary celebration of the life of Ieyasu. They stand, too, as a testament to the skills of almost four centuries’ of carpenters, carvers, metalworkers and painters. 

Toshogu in Nikko, Tochigi Prefecture. The shrine has been undergoing its latest renovation program since 2007 and work continues. JAPAN JOURNAL PHOTO


The famous “three wise monkeys” decorative panel at Toshogu, recently refreshed using traditional techniques JAPAN JOURNAL PHOTO


Detail of a pillar showing some of the elaborate carving, metalwork, lacquerwork and painting techniques that characterize Toshogu. JAPAN JOURNAL PHOTO


At Kinkaku-ji in Kyoto, the walls of two floors of the “Golden Pavilion” are covered entirely in gold leaf, the production of which is another technique inscribed on the UNESCO list.

First built in 1396, the pavilion survived a number of natural and other calamities until December 1950 when a schizophrenic monk burned the place down. At the time of its destruction, the building had all but lost its golden luster, and it was very much a case of “building back better” when reconstruction of the building was completed in 1955. The entsuke gold leaf which now covers the walls is created by putting gold between sheets of ultra-thin Japanese paper and pounding it. Master craftsmen in Kanazawa, where some 98% of gold leaf in Japan is made today, are said to be able to flatten out a coin-sized nugget of gold to the size of a tatami mat. A little goes a long way, in other words.

Kinkaku-ji, the Golden Pavilion, in the snow PUBLIC DOMAIN VIA WIKIPEDIA

In December 2020, scheduled work to repair and replace the thatched roofs of Kinkaku-ji was completed for the first time in eighteen years. The work, which entailed replacing tens of thousands of cypress bark shingles, took four months. The hoo phoenix ornament atop the roof received a thorough regilding too.  

Kinkaku-ji is a shining example of the range of traditional skills, techniques and knowledge needed for the conservation and transmission of wooden architecture in Japan.

Alex Hendy, The Japan Journal

This article first appeared in the Jan/Feb 2021 issue of the Japan Journal.


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