The slab is one item, not two
A slab fails at the interface between concrete and steel, so it is worth buying both from a supplier who has to answer for both. When cover blocks are wrong, or the bar diameter substituted, or the mix arrives with the slump gone, there is one desk to call.
Sequencing beats price by a mile
Steel that lands a week early sits in the mud. Concrete that lands an hour early sets in the drum. We plan the two against the same programme, so the tonnage and the cubic metres arrive against the same date, not against two separate order books.
Rates you can put in a BOQ
Basic rate, GST and freight are quoted as three separate lines for steel; basic rate, pumping and GST as three separate lines for concrete. Nothing appears on the invoice that was not on the quotation.