Abstract:
Involvement of the cost advisers -in the early stage of the building design process (briefing
stage) for the forecasting of probable cost of projects is often minimal.
The traditional pre tender estimating techniques such as unit method, cost per unit floor area
method, cube method, approximate quantities method and the like used to forecast the
probable cost of projects are not satisfactory. This bars the cost adviser to make the fullest
contribution in the early design stage decisions.
The surveys conducted in this research revealed the fact that local design practice with
respect to design stage estimating is limited to unit method, cost per unit floor area method
and later stage approximate quantities method and elemental cost method. The use of
computer facility to automate tasks in local practice is very low. Quantity surveyors in design
offices use spreadsheet software for calculations. Use of database software or other
programming languages in the process of cost advice was not evidenced.
This research is, thus, aimed at establishing a computer aided cost model based on bill of
approximate quantities properly linked to Standard Method of Measurement (SMM) with the
flexibility in application during briefing, sketch plan and working drawing stages. Being
linked to SMM, the proposed model ensures transformation of design and cost data into a
BOQ prepared in accordance with SMM.
The current practice of using bill of approximate quantities for cost forecasting is limited to
later stages of the design process since the method requires design information to work upon.
This difficulty has been overcome in the proposed model by incorporating design and cost
data libraries with computer manipulation.
.. A case study was used to generate quantities, compile historical design data, and provide
causal relationships to the model. These data coupled with solution neutral design
information were used to develop design data library and cost data library of the model which
provide sufficient information to make professional judgements at the briefing stage.
