What okiyane means
Okiyane is a roof arrangement used on clay-walled storehouses in which a separately framed timber roof is set on top of a roof whose underlayer has been sealed with clay and lime plaster, and the upper roof is then covered with tiles or sheet metal. A storehouse resists fire by coating not only its walls but also its roof deck in clay, yet a plastered surface does not stand up well to rain. The usual explanation is that okiyane separates the two tasks: the sealed layer resists fire and the roof above it sheds water.
The upper roof is generally not fixed directly to the sealed layer but raised on short posts. Air can move between the two layers, which is said to keep heat from building up in the roof space. If a fire burns the upper roof and brings it down, the sealed layer beneath can still protect the goods inside.
Most such roofs are gabled, and besides pantile roofing, sheet metal is common in cold regions. Registration records for a group of storehouses around Hirakawa in Aomori Prefecture repeatedly describe gabled okiyane roofs covered in sheet iron.
Reading the records and the building
Records phrase it in several ways. A rice storehouse of the Iida family is described as gabled with an okiyane pantile roof, its pawn storehouse as having an okiyane roof that is gabled and tiled, and a rice storehouse of the Hatakoshi family as gabled in the okiyane manner. The Iida record adds that even the tiled lean-to on the east side was treated the same way, with its rafters plastered over before the upper roof was set on.
From outside, look at the junction of the eaves and the wall. On an okiyane storehouse the timber roof sits slightly clear of the thick plaster band at the top of the wall, and from the gable end a gap or separate members may be visible between the sealed roof and the one above. Deep eaves with exposed timber on their undersides are another sign that the upper roof was framed separately.
Many such roofs have been replaced in repairs. The record for the Hatakoshi family's miso storehouse states that the roof was renewed in recent years while keeping the traditional okiyane form, so the form and the age of the materials need to be read separately.
References
- 飯田家住宅米蔵｜国指定文化財等データベース（文化庁）
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00005174
- 飯田家住宅文庫蔵・隠居屋｜国指定文化財等データベース（文化庁）
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00005169
- 波多腰家住宅米蔵｜国指定文化財等データベース（文化庁）
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00001699
- 佐藤義秋家住宅土蔵｜青森県
- https://www.pref.aomori.lg.jp/soshiki/kyoiku/e-bunka/torokuyukei_35.html
Last verified: 2026.09.26