Floor Joists

Floor Joists are a series of structural timbers that span from one load bearing wall to another, usually 400mm or 600mm apart. They essentially support the floorboards above and often the ceiling underneath.
There are various forms of floor joists in the use of modern construction that can be used for different purposes and often the structural engineer will advise on this selection to suit each requirement, depending on the length the joists are required to span and what loads the joists are required to support from above.

Traditionally floor joists would be solid timber, but modern engineered technologies have created options such as I- joists and steel web (Pozi) joists. These are often employed to span greater distances with other benefits, including a 360-degree service run potential within the depth of the floor joist zone. These engineered joist types are generally lighter in weight than traditional solid timber joists.

A series of parallel joists may be given additional rigidity by intermediate bracing running between them and perpendicular to the joists. Rigidity systems can include the use of noggins or herringbone struts to prevent joists twisting when under load.