In Unit, estimating was defined as "careful and correct measurement of various quantities involved in a construction project as reflected in contract documents and drawings and the subsequent calculation and application of accurate unit prices to these quantities". Principles involved in such estimating were also described in detail therein.
In this unit, typical examples of structures will be taken up for quantification. One example of a structure is given a complete treatment including costing whereas in other examples, only quantification of items of work (without costing) is given. This curtailing is made to primarily make the size of the unit concise; the secondary reason, of course, is that while quantities of items of work remain unaltered as long as the drawings/ specifications are not altered, cost varies from site to site and time to time.
It is emphasized that the availability of detailed, precise and well-dimension ed drawings form an essential prerequisite for accurate estimating on the one hand. On the other, the estimator or the quantity surveyor is expected to possess adequate knowledge to correctly read the drawings, interpret abbreviations and specifications, infer any missing data and correctly apply appropriate formula using principles of mensuration. At times, the estimator may have to make independent decisions without consulting the architect or the engineer in order to complete the job on hand in time. There is a vast array of codes, standards, regulations and legislation which apply to construction processes and cause either opportunities or restraints in the use of specific materials, methods or systems. A general knowledge of these is invaluable to the estimator in making independent decisions. More importantly, the estimator should have intimate knowledge of the working procedures, strengths and limitations of phisher company or organisation in order to have access to reliable data on labour productivity, equipment utilization and material costs including transportation so that the cost estimates prepared by higher are accurate.
Objectives
After studying this unit, you should be able to
- apply the principles learnt in previous unit to estimate actual structures,
- describe precisely the procedure of costing structures as a "three-component" exercise,
- determine the cost of any structure/project,
- conceptualize that the degree of accuracy of the estimate critically depends upon the degree of detail with which drawings, specifications and cost data are furnished,
- gain confidence to take up any structure for estimating,
- seek any missing relevant drawings/data, if you are given an exercise of estimating,
- appreciate the commonly stated principle that "practice makes things perfect" and try out more examples on your own, and
- have a feel for the applications of programs designed for construction estimating using personal computers (PCs).
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