A joist, in architecture and engineering, is one of the horizontal supporting members that run from wall to wall, wall to beam or beam to beam, to support a ceiling, roof (or floor). It may be made of wood, steel or concrete. Typically a beam is bigger than a joist and thus is distinguished from a joist. Joists will often be supported by beams. Joists support the sub-floor (floor deck) directly.

Cf rafter.

Ceilings

تیرچه | Solive | Legar