ProCalc calculates the mid-point then adds/subtracts 10% as our goal is to mimic the market place.
We do this for three reasons:
a. Design is highly conceptual at this stage so + or – 10% provides a sensible range,
b. Truly competitive tenders typically generate a range whereby the lowest price is 20% below the highest price (reinforcing the + or – 10% differential)
c. Builders apply margins of 13% to 33% (which ProCalc’s range caters for)
GST is included in ProCalc’s figures
OPC, Opinion of Probable Cost, Margin, Mark up