Kawara (English name) roof tile

Japanese: 瓦 - かわら（英語表記）roof tile

It is one of the most common roofing materials, and can be broadly divided into clay tiles and cement tiles, but there are also tiles made from other special materials. In recent years, new roofing materials other than the traditional clay and cement tiles have been manufactured using new materials, such as shingles (made by soaking asphalt roofing base paper in straight asphalt and attaching colored sand to the surface to form a certain shape. There is also a non-flammable shingle that does not use asphalt as a core material and is made from a mixture of glass fiber, synthetic resin, and mineral powder), asbestos slate (made by kneading cement and asbestos and compressing it into a corrugated or tile-shaped or flat shape like a shingle), glass tiles (made by casting glass into a tile shape for the purpose of letting in light), and metal tiles (made by forming a metal plate with a colored rust-proofing treatment on the surface into a tile shape). Compared to products made from these new materials, clay roofing tiles have drawbacks such as being heavy, less earthquake-resistant, and easily damaged by impact or frost damage, and so demand for them temporarily declined, but their superior properties such as appearance, water and fire resistance, insulation, and durability have begun to be reevaluated, and research into making them stronger, tougher, and lighter has become active, leading to an increase in their use in recent years. Currently, the most commonly used roofing tiles are clay roofing tiles and cement roofing tiles.

[Kishiyama Koichi]

Clay roofing tiles

The raw material is low-grade clay obtained by removing coarse sand, organic matter, and alkali from the subsoil obtained from ordinary fields. The collected raw soil is crushed into fine powder in a grinder, dissolved, sieved, dehydrated, and kneaded. The tiles are made by leaving the clay to sit in a dark room for a certain period of time, and then kneading it again. The tiles are then made in the following order: rough shaping, finishing, drying, firing, and cooling.

Clay tiles are called different names depending on the firing method and shape. They can be broadly divided into four types based on the firing method: (1) unglazed tiles (those that are simply fired after being molded and dried; red or brown in color), (2) smoked tiles (also called black or silver tiles; pine needles or wood are smoked in the final firing process, and carbonaceous matter is fixed to the surface), (3) salt-baked tiles (also called red tiles; salt is added at the end of the firing process, causing the decomposed sodium gas to react with the silicic acid components in the clay, forming a glassy substance on the surface; reddish brown in color), and (4) glazed tiles (those that are molded and dried, then coated with glaze and fired to form a glassy substance on the surface; there are many colors depending on the glaze).

They are also divided into Japanese-style tiles (Japanese roof tiles) and Western-style tiles according to their shape. Japanese-style tiles are classified according to the area and shape of use, such as (1) flat tiles (tiles with a slightly arc-shaped cross section, used between round tiles), (2) sangawara (tiles with a corrugated cross section, covering most of the roof surface), (3) noki tiles (also called arabesque tiles, used on the eaves), (4) maruki tiles (tiles with a semicircular cross section, used to connect tiles or to cover the ridge line), (5) oni tiles (tiles attached as decoration to the tops of the ridge, corner ridge, and descending ridge), (6) mendo tiles (tiles used to fill the gap between sanuki tiles and noshi tiles), and (7) mitsumata tiles (a type of round tile used at the point where the ridge lines of a hipped roof meet on three sides).

There are various types of Western-style tiles, such as flat tiles, S-shaped tiles, triangular crown tiles, Mission tiles, Italian tiles, Spanish tiles, Chinese tiles, Greek tiles, English tiles, French tiles, etc. Most Western-style tiles are glazed tiles, which have a glossy surface and low water absorption, making them highly waterproof and weather resistant.

[Kishiyama Koichi]

Cement roof tile

The raw material is mortar made by kneading cement and hard fine aggregate, and regular cement tiles are made by manually packing this into a mold, sprinkling cement powder on it to make the surface smooth, and then curing it. Recently, mortar with a large amount of cement has been molded using a high-pressure press, cured underwater and in the air, and then the surface is further baked with an electrostatic coating to produce tiles that have significantly improved strength, durability, and waterproofing compared to conventional cement tiles. The shape is almost the same as clay tiles.

Tile production is carried out almost throughout the country, mainly by small and medium-sized industries, but clay tiles are concentrated in Aichi Prefecture (Sanshu tiles), Kyoto Prefecture (Kyoto tiles), Osaka Prefecture (Senshu tiles), Ishikawa Prefecture (Noto tiles), Shimane Prefecture (Sekishu tiles), and other areas where high-quality clay can be extracted. There are also tiles that are rooted in the local climate, such as Okinawa's Ryukyu tiles, which have a unique feel.

[Kishiyama Koichi]

Japanese roof tiles

There are two types of tile roofing in Japan: honkawarabuki (roof tiles with tiled roofing) and sankawarabuki (roof tiles with tiled roofing). Honkawarabuki (roof tiles with tiled roofing) is a style in which flat and round tiles are laid alternately, and has been used since the technique was introduced from Baekje in the first year of the reign of Emperor Sushun (588) during the Asuka period. Round tiles are usually cylinders with a diameter of about 15 to 17 centimeters, divided into two, while flat tiles are usually squares with sides of about 30 centimeters, and are usually slightly curved. Round tiles are usually arranged with a beaded edge on the overlapping part and butted together, but there are also round tiles that are narrowed into a cone shape, and this method of laying round tiles by overlapping them is called Gyokibuki (roofing with tiled roofing). There are very few surviving examples of Gyoki roofing, such as Gokurakubo at Gangoji Temple in Nara, Hoto-ji Temple in Kyoto, Jodo-do Hall at Jodo-ji Temple in Hyogo, and Fuki-ji Temple in Oita. Flat tiles are laid on top of each other, offset slightly. Sangawara-buki is a style of roofing using only one type of sangawara, invented during the Edo period. Sangawara is a type of roofing using only one type of sangawara. Sangawara is a type of roofing using flat tiles, with one side of the tiles used in hon-kawara roofing folded in the opposite direction to the curve, and two diagonal corners missing. This reduces the amount of overlap when laid, and reduces the weight by not using round tiles. In addition, hook-type sangawara, which have protrusions on the back side, are laid by hanging them on battens hammered into the roof boards, eliminating the need for clay that had previously been laid on the roof boards to stabilize the tiles, making the roof even lighter. From the end of the Edo period to the present, hook-type sangawara has been the most common style of tile roofing.

In addition to the basic tiles mentioned above, there are also noshi tiles, ganburi tiles, wachigai tiles used to make the ridge, toribusuma tiles, onigawara tiles, shibi tiles that decorate the edge of the ridge, abumi tiles and noki tiles that decorate the eaves, as well as mendo tiles, tarukisaki tiles, sumikisaki tiles, and sumikibuta tiles.

Of these, onigawara (rice roof tiles), shibō (ridged tail), stirrup (big eaves) and ugawara (ridged roof tiles) characterize roofs with their shapes and patterns. Onigawara (rice roof tiles) and shibō (ridged tail) have both been used since the Asuka period, but up until the Hakuho period, lotus flower patterns were the main decorative motif for onigawara (rice roof tiles), and it was not until the Tenpyo period that onigawara (rice roof tiles) with demon face patterns first appeared. Shibō (ridged tail) were widely used on the main buildings of temples during the Asuka and Hakuho periods, but onigawara (rice roof tiles) gradually became more common, and from the Middle Ages onwards, they were almost never used, except for the use of shachi (roof ornamental fish) in early modern castle architecture. In ancient times, lotus flower patterns were the most common motif for stirrup (eaves round) tiles, but circles alone, such as jukenmon (juuken pattern) and hōsōge (hosoge) patterns, were also used occasionally. In the Heian period, comma shaped flowers, five-ringed pagodas, wheel jewels and characters came to be used as motifs, and family crests were used in early modern castles and palaces. Arabesque patterns were the mainstream for eaves tiles at first, but as time went on, they became more diverse.

Green-glazed tiles have been excavated from the East Precinct of Heijo Palace, Toji Temple in Kyoto, and Heian Palace, and tri-colored glazed tiles have been excavated from Toshodaiji Temple in Nara, making it clear that glazed tiles were used in Japan, albeit in small numbers.

In addition to the ceramic tiles mentioned above, wooden tiles are used on the Golden Hall of Chusonji Temple and stone tiles are used on the main tower of Maruoka Castle in Fukui. Metal tiles are also known, such as the copper tiles on Nikko Toshogu Shrine and the lead tiles on Kanazawa Castle's Ishikawamon Gate, but these are not made from metal tiles, but rather a base made of wood in the shape of real tile roofing, on which copper or lead sheets are laid to make it look like tiled roofing. Most of these non-ceramic tiles are used in cold regions or for fire prevention purposes.

Ceramic tiles have been used since ancient times in mainland China, the Korean Peninsula, and also in Europe. There are records that tiles were made in mainland China during the Xia dynasty, and relics can be found from the Spring and Autumn Period and Warring States Period. Furthermore, images and Ming wares make it clear that palaces and castles were covered with tiles during the Han dynasty. During the Tang dynasty, they were widely used for temples, palaces, and capital cities, and palaces and tombs built during the Ming and Qing dynasties were decorated with tiles glazed in yellow, blue, indigo, and other colors. Furthermore, ridge ornaments were more commonly used than onigawara (demon tiles), and many types of running animals can be seen on the ridges of roofs.

In Europe, tiles are widely used in areas bordering the Mediterranean Sea, including Spain, southern France, and Italy.

[Hirai Sei]

Types of tiles (Japanese style tiles)
©Shogakukan ">

Types of tiles (Japanese style tiles)

Type of tile (Western-style tile)
©Shogakukan ">

Type of tile (Western-style tile)

Roofing methods and names of tiles (sangawarabuki)
©Shogakukan ">

Roofing methods and names of tiles (sangawarabuki)

Roofing methods and names of tiles (honkawarabuki)
©Shogakukan ">

Roofing methods and names of tiles (honkawarabuki)

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

Japanese:

代表的な屋根葺(ふ)き材料の一つで、粘土瓦とセメント瓦に大別されるが、ほかに特殊な材料によるものもある。近年、従来の粘土瓦、セメント瓦以外の新しい屋根葺き材料としてシングル（ストレートアスファルトをアスファルトルーフィング用原紙に浸透させ、表面に着色した砂を付着させ一定の形にしたもの。ほかに芯(しん)材にアスファルト系材を用いず、ガラス繊維と合成樹脂、鉱物粉末混合材からつくられる不燃性のシングルもある）や石綿(せきめん)スレート（セメントと石綿を混練し、波形や瓦形、あるいはシングルのように平形に圧縮成形したもの）、ガラス瓦（採光を目的とし、ガラスを瓦状に鋳造成形したもの）、金属瓦（表面に着色防錆(ぼうせい)処理を施した金属板を瓦形にしたもの）など、新素材を使用した製品が製造されている。粘土瓦は、これらの新素材によってつくられた製品に比べ、重量が大きく耐震性に劣り、衝撃や凍害によって破損しやすいなどの欠点があり、一時需要が減少していたが、外観や耐水・耐火性、断熱性、耐久性など優れた点が見直され始め、また高強度化と靭性(じんせい)化、軽量化などの研究も盛んに行われるようになり、最近ではその使用も増大している。現在、瓦として多く用いられているものは粘土瓦とセメント瓦である。

［岸谷孝一］

粘土瓦

原料は、通常の田畑で得られる下層土から粗粒砂や有機物、アルカリ分などを除いた低級粘土で、採取した原土を粉砕機にかけて微粉砕し、これを溶解し、ふるい→脱水→混練の各工程を経てつくられる。瓦は暗室中で一定期間ねかせ、成熟させた粘土を再混練し、荒地成形→仕上げ→乾燥→焼成→冷却の順で製造される。

　粘土瓦は、焼成方法と形状により呼び名が異なる。焼成方法によって、(1)素焼瓦（成形乾燥したものを単に焼き締めたままのもの。色は赤および褐色）、(2)いぶし瓦（黒瓦、銀色瓦ともいい、焼成の最終工程に松葉や松木をたいていぶし、表面に炭素質を固着させたもの）、(3)塩焼(しおやき)瓦（赤瓦ともよばれ、焼成末期に食塩を投入し、分解したナトリウムガスと粘土中のケイ酸成分を反応させ、表面にガラス質を形成させたもので赤褐色）、(4)釉薬(ゆうやく)瓦（成形乾燥させたものに釉薬をかけて焼き、表面にガラス質を形成させたもの。釉薬により多種の色がある）の4種に大別される。

　また形状により和型瓦（日本瓦）と洋型瓦とに分けられる。和型瓦は使用箇所や形に応じ、(1)平瓦（断面がわずかに円弧状をなすもので、丸瓦と丸瓦との間に葺く瓦）、(2)桟瓦(さんがわら)（横断面が波形をしており、屋根面の大部分を覆う瓦）、(3)軒(のき)瓦（唐草(からくさ)瓦ともいい、軒端に葺く瓦）、(4)丸瓦（断面が半円状のもので、瓦と瓦をつないだり、棟線を葺くときに用いる）、(5)鬼瓦（大棟、隅棟、下り棟などの先端に装飾としてつける瓦）、(6)面戸(めんど)瓦（桟瓦とのし瓦とのすきまを埋める瓦）、(7)三つ叉(みつまた)瓦（寄棟屋根の棟線が三方からぶつかる点に用いる丸瓦の一種）などがある。

　洋型瓦には、平板瓦、S型瓦、三角冠瓦、ミッション瓦、イタリア瓦、スペイン瓦、支那(しな)瓦、ギリシア瓦、イギリス瓦、フランス瓦などの種類がある。洋型瓦はほとんどのものが釉薬瓦で、表面には光沢があり吸水性が低く、防水性、耐候性に富む。

［岸谷孝一］

セメント瓦

原料は、セメントと硬質細骨材とを混練したモルタルで、通常のセメント瓦は、これを型に手詰めし、表面を平滑にするためセメント粉末を振りかけたのち養生を行い製造される。最近では、セメント量の多いモルタルを高圧プレス成形し、水中・気中養生したものの表面にさらに焼付け静電塗装を行い、従来のセメント瓦に比べ耐力・耐久・防水性を大きく向上させたものも製造されている。形状は粘土瓦とほぼ同じである。

　瓦の生産は中小工業が主体に、ほぼ全国で行われているが、粘土瓦については、良質の粘土が採取できる愛知県（三州瓦）、京都府（京瓦）、大阪府（泉州瓦）、石川県（能登(のと)瓦）、島根県（石州瓦）などに集中している。独特な味わいをもつ沖縄の琉球(りゅうきゅう)瓦のような風土に根づいた瓦もある。

［岸谷孝一］

日本の瓦

日本で使われてきた瓦葺きの屋根葺きの形式には、本瓦葺きと桟瓦葺きとがある。本瓦葺きは平瓦と丸瓦を交互に並べて葺く形式で、飛鳥(あすか)時代崇峻(すしゅん)天皇元年（588）に百済(くだら)からその技術が伝えられて以来使われてきた。丸瓦は直径15～17センチメートル程度の円筒を二分した形、平瓦は1辺30センチメートル程度の方形で、やや湾曲した形が普通である。丸瓦は重なり部分に玉縁をつけ、突きつけて並べるのが普通であるが、全体を円錐(えんすい)形に細めた丸瓦もあり、この丸瓦を重ねながら葺く葺き方をとくに行基(ぎょうき)葺きとよんでいる。行基葺きの遺例はきわめて少なく、奈良の元興寺(がんごうじ)極楽坊、京都の宝塔寺、兵庫の浄土寺浄土堂、大分の富貴寺にみられるくらいである。平瓦は少しずつずらしながら重ねて葺いている。桟瓦葺きは、江戸時代に発明された桟瓦1種類だけで葺く形式である。桟瓦は、本瓦葺きの平瓦の1辺を湾曲とは反対に折り曲げ、二つの対角を欠いた形で、葺くときの重なり部分が少なく、丸瓦を使わないため重量を軽減することができた。また、桟瓦の裏面に突起をつけた引掛け桟瓦は、野地板に打った桟に掛けて葺き、それまで瓦を安定させるため野地板の上に敷いていた粘土が要らなくなり屋根がいっそう軽くなった。幕末から現在に至るまで引掛け桟瓦が瓦葺きのもっとも一般的な形式になっている。

　以上の基本的な瓦のほかに、棟をつくるためののし瓦、雁振(がんぶり)瓦、輪違(わちがい)瓦、棟の端を飾る鳥衾(とりぶすま)、鬼瓦、鴟尾(しび)、軒先を飾る鐙(あぶみ)瓦、宇(のき)瓦、そのほかに面戸(めんど)瓦、棰先(たるきさき)瓦、隅木先(すみきさき)瓦、隅木蓋(すみきぶた)瓦などがある。

　これらのうち鬼瓦、鴟尾、鐙瓦、宇瓦は、形状や文様によって屋根を特徴づけている。鬼瓦、鴟尾はともに飛鳥時代から使われているが、鬼瓦の文様は白鳳(はくほう)時代までは主として蓮華(れんげ)文が装飾として使われ、天平(てんぴょう)時代になって初めて鬼面文の鬼瓦が現れる。鴟尾は飛鳥時代、白鳳時代には寺院の主要な建物を中心に盛んに使われているが、鬼瓦がしだいに多くなり、中世以降になると近世の城郭建築に鯱(しゃち)が使われたほかは、ほとんど使われなくなった。鐙瓦（軒丸瓦）の文様は古代には蓮華文がもっとも一般的であったが、円だけを描いた重圏文、宝相華(ほうそうげ)文などもわずかに用いられていた。平安時代になると巴(ともえ)、五輪塔、輪宝、文字などが文様として用いられるようになり、近世の城郭や宮殿などでは家紋が使われている。宇瓦（軒平瓦）の文様は初め唐草文が主流であるが、時代が下るとともに多彩になる。

　平城宮東院や京都の東寺、平安宮からは緑釉のかかった瓦が出土し、また奈良唐招提寺(とうしょうだいじ)からは三彩釉の瓦が出土しており、わずかではあるが日本でも釉(うわぐすり)のかかった瓦が用いられていたことが明らかである。

　以上の陶製の瓦のほかに、中尊寺金色堂などには木製の瓦が、福井の丸岡城天守などには石製の瓦が使われている。また、日光東照宮などの銅瓦葺き、金沢城石川門などの鉛瓦葺きなど、金属を用いたものが知られているが、これらは、金属で瓦をつくって葺いたのではなく、木で本瓦葺きのような形の下地をつくり、その上に銅板や鉛板を張って瓦葺きにみせたものである。これらの陶製以外の瓦は多くは寒冷地で用いられるか、防火の目的で使われている。

　陶製の瓦は、中国大陸、朝鮮半島はもとより、ヨーロッパにおいても古代から使われている。中国大陸では夏(か)の時代に瓦がつくられていたという記録があり、春秋戦国のころになれば遺品がみられるようになる。さらに漢代には、画像や明器(めいき)によって宮殿や城郭などが瓦葺きであったことが明らかである。唐代には寺院、宮殿、都城などに広く用いられ、明(みん)・清(しん)代につくられた宮殿、陵墓などは黄色、碧(へき)色、藍(あい)色などの釉を施した瓦で飾られている。また、棟の飾りは、鬼瓦よりは鴟尾が多く用いられ、下り棟には何種もの走獣がみられるものが多い。

　ヨーロッパでは、瓦は、スペイン、南フランス、イタリアなどをはじめ、地中海に面した地域に多く用いられている。

［平井　聖］

瓦の種類（和型瓦）

瓦の種類（洋型瓦）

瓦の葺き方と名称（桟瓦葺き）

瓦の葺き方と名称（本瓦葺き）

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