Kawara (tile) (瓦)
A tile named Kawara is a material mainly used to cover roofs with.
The name "Kawara" originally refers to a clay tile, and in Germany, for example, a tile made of clay is called Ziegel (tile) to distinguish it from the other tiles made of different materials. General understanding in Japan is that a word "Kawara" refers to a clay roof tile in a certain shape, such as Hongawara (formal tile) and pantile. There are various categorization methods such as by style, purpose, burning method, color, grade and production region, therefore, when classified, there are more than 1000 kinds of Kawara. Especially 'Onigawara' (Japanese gargoyle roof tile), to which a devil face is applied, has also a good reputation as a work of art.
The biggest roof-tile kiln currently in service in Japan is a tunnel kiln whose dimensions are 110m in length and one line and 12 rows of flat-type tiles in width. The longest tunnel kiln is 125m in length (one line and nine rows of flat-type tiles in width).
A roof covered with Kawara tiles is also called 'Karawabuki,' 'Kawarabuki-yane' or 'Iraka.'
The "Iraka" roof in Japan is often horizontal at the top. Laying Kawara tiles on a roof is called "Kawara wo fuku," and workmen who are in charge of tile roofing are sometimes called "Kawara buki" workmen.
Tiles, which are made of material other than clay and have a Kawara shape, are also named Kawara with the material name added at the head of the names. The names such as stone roof tile and copper tile were used in the history. Kawara tiles made of cement or metal are still used today instead of clay tiles if normal clay tiles can not be used because of cold climate or depending on personal preference.
As described above, Kawara is a material used to cover roofs with (See also "Kawarabuki" (Tiled roof)). Not only for the purpose of roof material, Kawara tiles are also used as wall materials, such as 'Namakokabe' (a wall with square tiles jointed with raised plaster) and 'Neribei' (daub wall), on which tiles or stones are put and fixed with clay, and sometimes used as tiles on a stylobate of temples and as a part of drainage canals.
There are applications other than civil engineering and architecture, such as breaking (Kawara-wari (smashing roof tiles)) in Karatedo (traditional Japanese martial art) and Chinese martial art. In addition, the term 'Kawara-wari' stands for a work to carry out roof allocation for laying out tiles in roofing industry. This is also called 'Jiwari' (distribution of space).
Kawara made of materials other than clay
If the Kawara tiles made of material other than clay have a shape similar to the Japanese clay Kawara, they are also named Kawara with the material name added at the head of the names, and manufactured and used. The Kawara tiles made of materials other than clay are used today under the names of such as metal roof tile, cement roof tile and glass roof tiles. There is also Kawara made of cement, which is originated in Europe.
Metal roof tile
In ancient times, a thin copper or lead plate was put on a wooden form in a shape of a flat tile, concave tile or yakugawara tile (roof tiles with a special purpose), and this tile was laid on a roof in the same manner as a clay tile. Today, metallic forms made of such as steel and aluminum are used without wooden forms. This tile is believed to have started when Ieyasu TOKUGAWA put them on the roof of the top floor, such as Nagoya-jo Castle large keep and Edo-jo Castle keep. It is believed that this type of tiles were used to reduce the tile weight for tall buildings. These tiles are sometimes substituted for clay tiles in cold areas, where clay tiles may be cracked.
Cement roof tile
This is literally a tile made of cement. This is made of mortar mixed with a ratio of three parts sand to one part cement. This is relatively inexpensive and has a variety of shapes. The methods to give colors to the tiles are to knead pigments or to apply coating after dried out. The tiles were weathered by the passage of time, and lost the color and surface luster, therefore maintenance works such as spray coating were required.
Glass roof tile
This is a tile made of glass. This tile is not transparent but is obscured like a soda glass. Some of them have a pantile shape, and are used often instead of a skylight window.
Stone roof tiles
This is a tile made of stone. One of the old examples is the tiles laid on the existing Maruoka-jo Castle keep, and these tiles are made of tuff. This was originated as a substitute of clay tile in cold areas, where clay tiles were unusable. Old type stone roof tiles are heavy and not easy to make. Other than tuff, some tiles are made of clay stones (slate).
Originally a word "slate" refers to clay stone, however, the word "slate roof tile" means not a tile made of clay stone, but means a cement tile made of cement mortar prepared in the ratio of one part of cement to two parts of sands.
It is believed that Kawara first appeared in the history about 2800 years ago in China. Kawara was introduced into Japan together with Buddhism from Baekje in 588, about 1420 years ago. It is believed that Kawara was first applied to Asuka-dera Temple. At that time, the roof was covered with plane tiles at first, and then concave tiles were laid at each joint, which is nearly the same as the present-day Hongawarabuki (a style of tile roofing in which round and square tiles are laid down alternately). In the Asuka period, application of Kawara was allowed for temples only. The oldest existing Kawara tiles in Japan were made in the Asuka period, and they are the ones on Gokuraku-bo Hondo (main hall) and Zenshitsu (room for Zen sitting meditation) of Gango-ji Temple.
It has been archaeologically proved that the roofs of the palaces such as Daigokuden (Council Hall in the Imperial Palace) were covered with Kawara tiles in the Fujiwara Capital, which was constructed at the end of the 7th century, therefore it is believed that Kawara was first used for the buildings other than temples at that time. One of the tile kiln remains from this time is the No. 17 kiln of the Muneyoshi roof-tile kiln (in present-day Yoshizu, Mino-cho, Mitoyo City, Kagawa Prefecture).
In the Nara and Heian periods, Kawara tiles have started to be used not only for temples and palaces, but also for Kanga (government offices). Especially Kawara tiles have started to be applied to buildings that symbolized the state power, such as Kokufu (provincial office) and provincial monasteries. According to the historical picture materials, however, the residences of nobles had Hiwadabuki (construction with the bark of hinoki, Japanese cypress), therefore it can be said that Kawara was used only for public buildings. The governmental offices called Gaoku were located throughout the country for producing and supplying Kawara tiles, and they supplied Kawara tiles to predetermined temples and government offices.
In medieval times, the roofs of buildings other than temples, such as Gosho (Imperial Palace) of emperors and Seii taishogun (literally, "great general who subdues the barbarians") were often covered with Hiwada (bark of Japanese cypress) again.
In recent times, Kawara has started to be used for castles, which were formerly temporary buildings in most cases. Especially in the Azuchi-Momoyama period, gilded Shachigawara (Shachihoko tile), Onigawara and eaves-end tiles were used (gilded tiles). Around the Edo period, metal tiles made of such as copper and lead have started to be used to reduce the roof weight. It is believed that a Kawara workman, Hanbe NISHIMURA has developed a pantile in 1674, which needs no concave tiles. Thanks to his development, the amount of Kawara tiles used has been reduced, therefore Kawara has become available for weaker buildings. In addition, fire prevention was one of urgent tasks for Bakufu (Japanese feudal government headed by a shogun) and each domain in peaceful time, therefore application of Kawara tiles was encouraged and spread among general houses. However, in regions with heavy snowfalls and in cold areas, tile roofing was not popular. This tendency is true at the present days, so more houses in northern Japan have metal plate roofing (a roof tile bar (semi-circular battens used for roofing) and flat roof tile (such as a straight line), etc.) and slate roofing.
In the Meiji period, western-style roof tiles have started to be developed and imported, and Hikkake sangawara (hanging tiles), an improved type of pantile have also been developed. Since 1926, Hikkake sangawara has been used as a standard tile for roofing due to encouragement by the prewar Ministry of Home Affairs of that time, and they are still used today.
Gakai' (tumbling of tiles) means a collapse of an organization.
According to the Kojien dictionary, Gakai describes a situation that if a part of Kawara collapses, most of the other will also fall down. In this case, Kawara refers to Chinese unglazed earthware such as 'Kawarake' (unglazed earthenware), therefore this idiom does not describes roof tiles falling down, but an unglazed clay pot broken into pieces (according to 'Bushu no hanashi' (a story about radicals) published by Cyuko new book).