Dictionary Meaning and Definition on 'Joist'
n : beam used to support floors or roofs
- Joist \Joist\, n. [OE. giste, OF. giste, F. g[^i]te, fr. gesir
to lie, F. g['e]sir. See Gist.] (Arch.)
A piece of timber laid horizontally, or nearly so, to which
the planks of the floor, or the laths or furring strips of a
ceiling, are nailed; -- called, according to its position or
use, binding joist, bridging joist, ceiling joist,
trimming joist, etc. See Illust. of Double-framed floor,
under Double, a.
- Joist \Joist\, v. t. [imp. & p. p. Joisted; p. pr. & vb. n.
To fit or furnish with joists. --Johnson.
Wikipedia Meaning and Definition on 'Joist'
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, and is thus distinguished from, a joist. Joists are often supported by beams and are usually repetitive.
The wider the span between the supporting structures, the deeper the joist will need to be if it is not to deflect under load. Lateral support also increases its strength. There are approved formulas for calculating the depth required and reducing the depth as needed; however, a rule of thumb for calculating the depth of a wooden floor joist for a residential property is half the span in feet plus two inches; for example, the joist depth required for a 14-foot span is 9 inches. Many steel joist manufacturers supply load tables in order to allow designers to select the proper joist sizes for their projects.[See more about Joist at Dictionary 3.0 Encyclopedia]