Hiwadabuki

Hiwadabuki (檜皮葺 or 桧皮葺) is a traditional Japanese roof covering made from the bark of hinoki, the Japanese cypress. Strips of bark are laid in many overlapping layers to build up a thick, soft-looking roof that can be shaped into the smooth curves and upturned eaves of shrine and palace architecture. It is one of the most prestigious roof coverings in Japan.

Technique

The bark is cut into strips, usually about 45-60 cm (18-24 in) long and 4-15 cm (1.5-6 in) wide. Roofers lay them in successive courses, each shifted only about 1-2 cm (0.4-0.8 in) beyond the one below, so that the finished roof is made up of very many layers. Each course is fixed with bamboo nails. The result is a dense, thick covering whose edges at the eaves show the layered build-up. Bark for roofing is traditionally harvested by specialist craftsmen.

History

Hiwadabuki is native to Japan. In the Heian period (794-1185) aristocratic mansions were roofed with layered cypress bark rather than the ceramic tiles used on Buddhist temples, and the technique became associated with imperial palaces and Shinto shrines, where tile was often avoided. Many shrine main halls and some temple halls still use it.

Heritage status

Cypress-bark roofing is a recognised conservation skill in Japan. In December 2020 UNESCO inscribed "Traditional skills, techniques and knowledge for the conservation and transmission of wooden architecture in Japan" on the Representative List of the Intangible Cultural Heritage of Humanity. Among its 17 component skills are cypress-bark and wooden-shingle roofing and the harvesting of Japanese cypress bark. Because the materials and specialist roofers are scarce, preservation associations train new craftspeople.

Examples

The JAANUS dictionary of Japanese architecture illustrates the technique with the Chokushimon (imperial messenger gate) of Engaku-ji in Kamakura. Other well-known hiwadabuki roofs include the main hall of Kiyomizu-dera in Kyoto and the main sanctuary of Izumo Taisha.

Related coverings

• Kokerabuki - thin wooden shingles, also fixed with bamboo nails.
• Kayabuki - grass thatch.
• Kawarabuki - clay tile roofing.