An abbreviation for rolled steel joist, which is a structural beam with an I-shaped or H-shaped cross section. These heavy beams carry structural loads over wide spans, typically supporting floors or roof structures in masonry and framing construction. The shape provides high stiffness and bending resistance for its weight.
The structural engineer called for a heavy RSJ to carry the load across the new open-plan living room.
Though the term originates from early steel manufacturing techniques, builders in many regions still use it as a catch-all name for any standard I-beam.
Also heard as
- I-beam
- H-beam
Related terms
Steel
Structural steel components used to frame or reinforce a building.
Steelwork
The complete assembly of structural steel components in a building.
Span
The unsupported distance between two structural supports.
Dead load
The permanent, stationary weight of a building's structural elements and fixed equipment.