Translation guide
A horizontal structural member used in framing to support a floor or ceiling. In Japanese, this is typically expressed with specific architectural terms depending on the context.
A horizontal beam that supports the floorboards and distributes the load to the main beams or walls.
The standard term for floor joists in Japanese construction. These are smaller beams laid across larger beams (大引) to support flooring.
根太の間隔は30センチです。
The joist spacing is 30 centimeters.
A horizontal beam that supports the ceiling finish and may also tie the walls together.
Specifically refers to ceiling joists. In traditional Japanese architecture, these are often visible and decorative.
天井根太に断熱材を入れる。
Put insulation between the ceiling joists.
A generic term for a horizontal structural member, not necessarily floor or ceiling specific.
A general term for a horizontal beam. Can be used for joists in a broader sense, but less specific than 根太.
横梁で床を支える。
Support the floor with horizontal beams.
A secondary beam that spans between main beams, similar to a joist in function. More common in steel or large timber structures.
The English word 'joist' does not have a single perfect equivalent in Japanese. The correct term depends on whether it is for a floor (根太), ceiling (天井根太), or a general horizontal member. Using the wrong term can cause confusion in construction contexts.
In traditional Japanese wooden floor framing, 大引 (おおびき) are the larger main beams, while 根太 (ねだ) are the smaller joists laid across them. This is similar to the distinction between 'girder' and 'joist' in English.
大引の上に根太を渡す。
Lay the joists across the girders.
根太を大引の上に固定する。
Fix the joists onto the floor beams.
Explicitly 'floor joist', used when distinction from ceiling joists is needed.
床根太が腐っている。
The floor joists are rotten.
Lightweight ceiling joists or furring strips used to attach ceiling boards. Common in modern drywall or traditional wood ceilings.
野縁を組んでから石膏ボードを張る。
After installing the ceiling joists, attach the drywall.
小梁の上にデッキプレートを敷く。
Lay the deck plate on the secondary beams.