JAPANESE CULTURE, EXPLAINED
合掌造り
Gassho-zukuri farmhouses in Shirakawa-gō and Gokayama have steep thatched gable roofs. Their attics once provided space for raising silkworms, linking the roof’s form to household production as well as snow.
A gable roof has two slopes meeting at a ridge, with triangular ends. Gasshō means palms joined in prayer; in architecture, it names the paired, inverted-V form. Inclined timbers form the framework: they meet at the top and rest on transverse members below. Horizontal members can divide the tall attic into working levels for silkworm rearing.
Gable openings admit light and ventilation. The roof structure leaves a broad interior without closely spaced upright posts. Diagonal bracing helps address weakness along the ridge direction.
Level land in the valleys was limited. A separate silkworm building would use land and add another roof to maintain in winter. Attic floors allowed living and production to occupy the same building, while thatch and ventilation helped manage conditions.
The heritage centre illustrates an eaves-entry house with ground-floor rooms for reception, daily living and cooking, a Buddhist altar and a stable; silkworm work took place above. The hearth gave heat for cooking, warmth and light. Smoke rose into the timbers and thatch, which Shirakawa-gō’s open-air museum explains helped dry the upper space and discourage insects and decay.
| マヤ | Stable for farm horses |
|---|---|
| ミンジャ | Household work area |
| オエ | Living and reception room |
| ダイドコ | Room with a cooking hearth |
| デエ | Tatami room before the Buddhist altar |
| チョウダ | Bedroom |
The Toyama house in Miboro, built around 1850 and inhabited until 1967, combined three uses. Silkworms occupied the attic; domestic, altar and reception spaces were on the ground floor, where a corridor separated the kitchen, bath and workroom. Beneath the floor was a saltpeter pit. Straw, soil, mugwort and silkworm waste fermented there over years to produce an ingredient for gunpowder, linking sericulture with another household industry.
Floor uses in the former Toyama house. Japan Tourism Agency: Toyama house
Entrances in Shirakawa-gō are commonly along the eaves, a form called hirairi. In Gokayama, gable-end entrances, or tsumairi, are more common. Both regions also have exceptions.
Carpenters built the lower post-and-beam structure with worked joints. Roof assembly and thatching traditionally relied on yui, reciprocal labour, with rope and flexible wooden ties connecting the roof framework. The heritage centre’s yui account books record labour and materials contributed, along with obligations to return the help.
Kaya refers to the plants used for thatching. They must be gathered, dried and stored before roof work begins. Workers remove old thatch, align new bundles on the slope and secure them with retaining timbers and ties. People inside and outside pass cord with long needles to fasten the roof covering.
In Shirakawa-gō, rethatching commonly covers half a roof at a time. Gokayama traditions also renew smaller sections as material supplies allow; old thatch can be reused or returned to fields. The heritage centre records a decline in reciprocal roof work there from the late 1950s, followed by greater reliance on specialists.
The heritage centre traces the form represented by surviving houses to around the late seventeenth century, with enlargement as production expanded in the eighteenth and nineteenth centuries. Postwar changes in sericulture, population and housing reduced their numbers. Ogimachi residents organised preservation in 1971; local ordinance and national preservation-district selection followed in 1976, and the three villages entered the World Heritage List in 1995.
Wood and thatch require continuing fire prevention. In Ogimachi, an elevated reservoir supplies fire-fighting installations that can form curtains of water against spreading flames. Residents take turns checking intakes and join an annual drill. Preservation also protects the fields, roads and woodland around the houses.
No. Attic space, daylight and ventilation for silkworm rearing also matter.
No. A building type is broader than the particular settlements included in the inscription.
Silkworm rearing.
It also requires fire prevention, working water supplies and protection of the surrounding settlement.