Short answer
Camber is a slight upward curve built into a steel beam so that, after the floor dead load is applied, the beam deflects down to level. It is specified in inches on the drawing or schedule, such as 3/4 in, and fabricators charge extra for it because the beam must be cold-bent or heat-cambered.
Why beams are cambered
Every beam sags under load. If a long beam carries a concrete slab, the dead-load sag can be visible and can cause ponding or an uneven floor. The engineer calls for a camber that approximately offsets the dead-load deflection, so the beam is high when delivered and flat once loaded. Camber is usually rounded to the nearest 1/4 inch and is seldom specified on short beams.
It is not a stress treatment and it does not add strength.
How camber shows up on drawings
Camber appears beside the beam size in the plan, as in W16x26 (C=3/4"), or in a column of the beam schedule. Some general notes say that beams over a given span are to be cambered unless noted otherwise. Read the notes and the schedule together.
The cambered beams must be tracked in the takeoff, because every one of them adds a charge. Count them by size and camber.
How does it affect the estimate?
Cambering adds shop labor or a subcontracted bending cost per piece, and it also affects handling and shipping because the beams must be set with the camber up. Some beams may not be cambered at all (cantilevers, short spans). When a schedule lists camber on a beam that is clearly too short for it, raise an RFI.
SteelFlo picks up camber callouts that sit beside members, so you can see which pieces carry one. See the camber estimating guide.
Which beams are cambered?
Typically longer composite floor beams and girders. Short beams, cantilevers and beams with moment connections are often left uncambered, and the engineer's general notes say so. Some engineers specify camber on every composite beam over a given span, and some limit it to a maximum size. When in doubt, read the notes and the schedule. If a short beam is marked with a camber, ask.
Camber and the shop
Fabricators camber beams cold by mechanical bending or with heat, and either method takes time. Some shops have a dedicated cambering machine, and others sub it out. The cost per beam depends on size and camber amount. When estimating, count cambered beams separately by size and add the shop's per-piece charge. Also account for shipping and erection: the beams have to be placed camber-up, so mark them clearly.
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