Basis of estimate
In order to understand exactly what the schedule of works means it is very important to define the basis of figures, measures and prices. So for example in the case of fair faced brick work there would be he need to express the cost which may be the basic item plus the additional materials and the labour required to complete the installation. Conversely it could be a lump sum price to include all these component parts as a cost/m². It is a decision by the architect and quantity surveyor how the components of the schedule and listings are presented. Obviously it is important to know exactly what the presented item includes by means of a clear unambiguous description to enable a cost to be appended to the goods in question or services. Of course the foregoing relates to a specific item in the schedule for costing but the basis of estimate will also define variations to be disclosed and allowed for if required. This may allow in the quotation for provisional sums which may subsequently firmed-up the to allow for the variation in supply/cost/availability at the time of fulfilment for the basis of estimate. For example a poured concrete price may be $x per m³ based on a cement price of $y per tonne but at the time of supply there may be change which is allowed for. All the basis of estimate does it to remove ambiguity.