Category: Structure & materials
Prepared by Eng. Ahmed Fathy, Projects Manager ·
Definition
Reinforcement is ribbed steel bars placed in concrete to carry tension. Bar sizes, numbers and positions are set on the structural drawings and bent to the bar bending schedule.
Why it matters on a project
Rebar is usually the largest cost item in a concrete frame, and any excess or shortfall against the design is either wasted money or a safety risk.
Measurement and pricing
Measured in tonnes from the bar bending schedule, plus cutting waste and laps according to the method of work.
Worked example
One metre of 12 mm bar weighs 0.00617 × 12² = 0.888 kg, so one tonne of this size gives about 1,126 linear metres.
Common mistake
Adding more steel than the drawings show in the belief that it is safer; congested bars can stop concrete flowing around them and weaken the element.
Frequently asked questions
How do I find the weight of a metre of rebar?
Weight per metre in kg = 0.00617 × diameter squared in mm.
Which bar sizes are common in villas?
Mostly 8 to 25 mm: small sizes for links and slabs, larger ones for columns, beams and footings.
Related terms
- Bar bending schedule (BBS)A schedule listing the diameter, length, shape and number of reinforcement bars per element.
- Reinforced concreteConcrete containing steel reinforcement to resist the tensile forces concrete alone cannot carry.
- Shop drawingsDrawings prepared by the contractor or fabricator showing how items are made and installed, approved by the consultant before execution.
- Waste allowanceA percentage added to material quantities to cover cutting, damage and site loss.
Read next
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