Hidden roof
Encyclopedia
The Also sometimes called . Koya is the technical term for the space between the roof and the ceiling. is a type of roof widely used in Japan both at Buddhist temples
and Shinto shrines. It is composed of a true roof above and a second roof beneath, permitting an outer roof of steep pitch to have eaves
of shallow pitch, jutting widely from the walls but without overhanging them. The first roof is visible only from under the eaves and is therefore called a "hidden roof" (giving its name to the whole structure) while the second roof is externally visible and is called an "exposed roof" in English and in Japanese. Invented in Japan during the 10th century, its earliest extant example is Hōryū-ji
's Daikō-dō
, rebuilt after a fire in 990.
and most Shinto architecture
are not indigenous, but were imported from China and Korea together with Buddhism around the 6th century. Climate in Japan being different from that on the continent, several structural adaptations became necessary, the most important of which is the noyane, invented some time during the Heian period (794-1185).
During the previous Nara period
(710-794), the structural elements of a roof were considered ornamental and therefore left exposed by design. The rafters supporting the roof's eaves
would enter the building and would then be visible from below. Above the rafters would be laid directly the roofing material, for example wood shingles. This is the structure we see at Hōryū-ji
's kon-dō
or five-storied pagoda
. Because the local climate is more moist than in either China or Korea, roofs had to have a steeper incline to help quicken the flow of rainwater. Due the permeable nature of the walls, and the lack of channelled roof drainage, it was necessary that eaves project far from the walls. On a roof of steep pitch, the wide eaves were also deep, restricting light to the windows and trapping humidity.
The solution devised by Japanese artisans was to construct a hidden roof raised above a ceiling which had non-structural rafter
s as aesthetic elements. From the hidden roof projected the principal rafters of the shallow-pitched eaves. The structural elements of the outer roof were raised above this, with an outer inclination completely independent of the pitch of the eaves. The earliest extant example of hidden roof is Hōryū-ji's Daikō-dō, built in 990 and was discovered only in the 1930s during repair work.
which, although arrived in Japan from China at the end of the 12th century, thus well after the invention of the hidden roof, never adopted it. Also, although all extant Zen
temples have it, it is likely that the Zenshūyō style, which arrived roughly at the same time of the Daibutsuyō, adopted the hidden roof only some time after its arrival.
Because the hidden roof allowed the structure of the roof to be changed at will with no impact on the underlying building, its use gave birth to many structural innovations. For example, Fuki-ji
's Ō-dō
has a square roof over a rectangular footprint. Ways were also found to make use of the space between the two roofs. For example, at Jōruri-ji in Kyōto (1107) part of the Hon-dō's ceiling was raised above the rest to give space to the room. Later it would become common to raise the exposed roof above the entire core of a temple building.
The same evolution we have seen in Buddhist architecture can be seen in the roofs of several Shinto architectural styles it influenced. The kasuga-zukuri
, nagare-zukuri
, hachiman-zukuri
, hie-zukuri all followed the evolution path we have seen. All extant examples of the ancient shinmei-zukuri
, taisha-zukuri
and sumiyoshi-zukuri
styles however show no sign of a hidden roof.
's Denpō-dō in the photo to the right, where the brown elements within the gable are all part of the roof's support system. After the adoption of the hidden roof, the tsumakazari remained in use, albeit with a purely decorative role.
provided in the intervals between bracket complexes (tokyō
) at religious buildings in Japan.
In origin they were necessary to support the roof above, however at the end of the 10th century the invention of the hidden roof, which had its own hidden supporting structure, made them superfluous. They remained in use, albeit in a purely decorative role, assuming a variety of forms, and are typical of the Wayō
style.
Buddhist temples in Japan
Along with Shinto shrines, Buddhist temples are the most numerous, famous, and important religious buildings in Japan.The term "Shinto shrine" is used in opposition to "Buddhist temple" to mirror in English the distinction made in Japanese between Shinto and Buddhist religious structures. In...
and Shinto shrines. It is composed of a true roof above and a second roof beneath, permitting an outer roof of steep pitch to have eaves
Eaves
The eaves of a roof are its lower edges. They usually project beyond the walls of the building to carry rain water away.-Etymology:"Eaves" is derived from Old English and is both the singular and plural form of the word.- Function :...
of shallow pitch, jutting widely from the walls but without overhanging them. The first roof is visible only from under the eaves and is therefore called a "hidden roof" (giving its name to the whole structure) while the second roof is externally visible and is called an "exposed roof" in English and in Japanese. Invented in Japan during the 10th century, its earliest extant example is Hōryū-ji
Hōryū-ji
is a Buddhist temple in Ikaruga, Nara Prefecture, Japan. Its full name is Hōryū Gakumonji , or Learning Temple of the Flourishing Law, the complex serving as seminary and monastery both....
's Daikō-dō
Dō (architecture)
is a Japanese word for building. It is very often used in Japanese Buddhism as a suffix in the name of some of the many buildings that can be part of a Japanese temple compound. The prefix can be the name of a deity associated with it is a Japanese word for building. It is very often used in...
, rebuilt after a fire in 990.
History and structure
Japanese Buddhist architectureJapanese Buddhist architecture
Japanese Buddhist architecture is the architecture of Buddhist temples in Japan, consisting of locally developed variants of architectural styles born in China...
and most Shinto architecture
Shinto architecture
Shinto architecture is the architecture of Japanese Shinto shrines.With a few exceptions, the general blueprint of a Shinto shrine is Buddhist in origin. Before Buddhism, shrines were just temporary structures erected to a particular purpose. Buddhism brought to Japan the idea of permanent shrines...
are not indigenous, but were imported from China and Korea together with Buddhism around the 6th century. Climate in Japan being different from that on the continent, several structural adaptations became necessary, the most important of which is the noyane, invented some time during the Heian period (794-1185).
During the previous Nara period
Nara period
The of the history of Japan covers the years from AD 710 to 794. Empress Gemmei established the capital of Heijō-kyō . Except for 5 years , when the capital was briefly moved again, it remained the capital of Japanese civilization until Emperor Kammu established a new capital, Nagaoka-kyō, in 784...
(710-794), the structural elements of a roof were considered ornamental and therefore left exposed by design. The rafters supporting the roof's eaves
Eaves
The eaves of a roof are its lower edges. They usually project beyond the walls of the building to carry rain water away.-Etymology:"Eaves" is derived from Old English and is both the singular and plural form of the word.- Function :...
would enter the building and would then be visible from below. Above the rafters would be laid directly the roofing material, for example wood shingles. This is the structure we see at Hōryū-ji
Hōryū-ji
is a Buddhist temple in Ikaruga, Nara Prefecture, Japan. Its full name is Hōryū Gakumonji , or Learning Temple of the Flourishing Law, the complex serving as seminary and monastery both....
's kon-dō
Main Hall (Japanese Buddhism)
Main hall is the term used in English for the building within a Japanese Buddhist temple compound which enshrines the main object of veneration. Because the various denominations deliberately use different terms, this single English term translates several Japanese words, among them Butsuden,...
or five-storied pagoda
Tō
The , sometimes also called or is the Japanese version of the Chinese pagoda, itself an interpretation of the Indian stupa. Pagodas are quintessentially Buddhist and an important component of Japanese Buddhist temple compounds but, because until the Kami and Buddhas Separation Act of 1868 a...
. Because the local climate is more moist than in either China or Korea, roofs had to have a steeper incline to help quicken the flow of rainwater. Due the permeable nature of the walls, and the lack of channelled roof drainage, it was necessary that eaves project far from the walls. On a roof of steep pitch, the wide eaves were also deep, restricting light to the windows and trapping humidity.
The solution devised by Japanese artisans was to construct a hidden roof raised above a ceiling which had non-structural rafter
Rafter
A rafter is one of a series of sloped structural members , that extend from the ridge or hip to the downslope perimeter or eave, designed to support the roof deck and its associated loads.-Design:...
s as aesthetic elements. From the hidden roof projected the principal rafters of the shallow-pitched eaves. The structural elements of the outer roof were raised above this, with an outer inclination completely independent of the pitch of the eaves. The earliest extant example of hidden roof is Hōryū-ji's Daikō-dō, built in 990 and was discovered only in the 1930s during repair work.
Influence
This structure not only solved drainage problems, but eliminated deep shadows and gave the whole temple a feel that was very different from that of its ancestors of the Asian continent. It was as a consequence extremely successful and was widely adopted all over the country. One important exception is the architectural style called DaibutsuyōDaibutsuyō
is a Japanese religious architectural style which emerged in the late 12th or early 13th century. Together with Wayō and Zenshūyō, it is one of the three most significant styles developed by Japanese Buddhism on the basis of Chinese models....
which, although arrived in Japan from China at the end of the 12th century, thus well after the invention of the hidden roof, never adopted it. Also, although all extant Zen
Zen
Zen is a school of Mahāyāna Buddhism founded by the Buddhist monk Bodhidharma. The word Zen is from the Japanese pronunciation of the Chinese word Chán , which in turn is derived from the Sanskrit word dhyāna, which can be approximately translated as "meditation" or "meditative state."Zen...
temples have it, it is likely that the Zenshūyō style, which arrived roughly at the same time of the Daibutsuyō, adopted the hidden roof only some time after its arrival.
Because the hidden roof allowed the structure of the roof to be changed at will with no impact on the underlying building, its use gave birth to many structural innovations. For example, Fuki-ji
Fuki-ji
is a Tendai temple in Bungotakada, Oita Prefecture, Japan. The temple was established in 718. Its Amida-dō is generally called Fuki-ji Ō-dō. It is the oldest wooden structure in Kyushu. Ō-dō is designated as a National Treasure. The seated image of the Amida-Nyōrai contained in Ō-dō is designated...
's Ō-dō
Dō (architecture)
is a Japanese word for building. It is very often used in Japanese Buddhism as a suffix in the name of some of the many buildings that can be part of a Japanese temple compound. The prefix can be the name of a deity associated with it is a Japanese word for building. It is very often used in...
has a square roof over a rectangular footprint. Ways were also found to make use of the space between the two roofs. For example, at Jōruri-ji in Kyōto (1107) part of the Hon-dō's ceiling was raised above the rest to give space to the room. Later it would become common to raise the exposed roof above the entire core of a temple building.
The same evolution we have seen in Buddhist architecture can be seen in the roofs of several Shinto architectural styles it influenced. The kasuga-zukuri
Kasuga-zukuri
is a traditional Shinto shrine architectural style which takes its name from Kasuga Taisha's honden. It is characterized by the use of a building just 1x1 ken in size with the entrance on the gabled end covered by a veranda. In Kasuga Taisha's case, the honden is just 1.9 m x 2.6 m.Supporting...
, nagare-zukuri
Nagare-zukuri
The or is a traditional Shinto shrine architectural style characterized by a very asymmetrical gabled roof projecting outwards on one of the non-gabled sides, above the main entrance, to form a portico . This is the feature which gives it its name. It is the most common style among shrines all...
, hachiman-zukuri
Hachiman-zukuri
The is a traditional Japanese architectural style used at Hachiman shrines in which two parallel structures with gabled roofs are interconnected on the non-gabled side, forming one building which, when seen from the side, gives the impression of two. The front structure is called , the rear one ,...
, hie-zukuri all followed the evolution path we have seen. All extant examples of the ancient shinmei-zukuri
Shinmei-zukuri
is an ancient Japanese architectural style typical of Ise Grand Shrine's honden, the holiest of Shinto shrines. It is most common in Mie prefecture.-History:...
, taisha-zukuri
Taisha-zukuri
is the oldest Shinto shrine style. Named after Izumo Taisha's honden , like Ise Grand Shrine's shinmei-zukuri style it features a bark roof decorated with poles called chigi and katsuogi, plus archaic features like gable-end pillars and a single central pillar...
and sumiyoshi-zukuri
Sumiyoshi-zukuri
is an ancient Shinto shrine architectural style which takes its name from Sumiyoshi Taisha's honden in Ōsaka. As in the case of the taisha-zukuri and shinmei-zukuri styles, its birth predates the arrival in Japan of Buddhism.-History:...
styles however show no sign of a hidden roof.
Tsumakazari
Before the invention of the hidden roof the so-called were simply structural elements left visible by design. See for example Hōryū-jiHōryū-ji
is a Buddhist temple in Ikaruga, Nara Prefecture, Japan. Its full name is Hōryū Gakumonji , or Learning Temple of the Flourishing Law, the complex serving as seminary and monastery both....
's Denpō-dō in the photo to the right, where the brown elements within the gable are all part of the roof's support system. After the adoption of the hidden roof, the tsumakazari remained in use, albeit with a purely decorative role.
Nakazonae
Another of the repercussions of the invention of the hidden roof was the role change undergone by struts called . Nakazonae are intercolumnar strutsStrut
A strut is a structural component designed to resist longitudinal compression. Struts provide outwards-facing support in their lengthwise direction, which can be used to keep two other components separate, performing the opposite function of a tie...
provided in the intervals between bracket complexes (tokyō
Tokyō
The Dougong in Chinese is a system of and supporting the eaves of a Japanese building, usually part of a Buddhist temple or Shinto shrine. The use of tokyō is made necessary by the extent to which the eaves protrude, a functionally essential element of Japanese Buddhist architecture. The system...
) at religious buildings in Japan.
In origin they were necessary to support the roof above, however at the end of the 10th century the invention of the hidden roof, which had its own hidden supporting structure, made them superfluous. They remained in use, albeit in a purely decorative role, assuming a variety of forms, and are typical of the Wayō
Wayō
is the name given to a style developed in art and architecture in Japan during the Heian period, mainly by the esoteric sects Tendai and Shingon. Together with Zenshūyō and Daibutsuyō, it is one of the three most significant styles developed by Japanese Buddhism on the basis of Chinese models.The...
style.