ESTIMATION OF CIVIL WORK
ESTIMATION
Estimate is a calculation of various items of an engineering works so as to know its approximate cost and quantities of various kinds of materials required with labour involved for its satisfactory completion.
Purpose of Estimating
1-To ascertain the necessary amount of money required by the owner/contractor to complete the proposed work.
2-For public construction works, estimates are required in order to obtain administrative approval, allotment of funds and technical sanction.
3-To ascertain quantities of materials required in order to program their timely procurement.
4-To calculate the number of different categories of workers that are to be employed to complete the work within the scheduled time of completion.
5-To assess the requirements of Tools, Plants and equipment required to complete the work according to the program.
6-To fix up the completion period from the volume of works involve in the estimate.
7-To draw up a construction schedule and program and also to arrange the funds required according to the programming.
8-To justify the investment from benefit cost ratio. (For ideal investment, this ratio should be more than one).
10-To invite tenders and prepare bills for payment.
11-An estimate for an existing property is required for valuation.
DATA FOR ESTIMATE
DRAWINGS
SPECIFICATION
RATES
DRAWINGS
Fully dimensioned and to the scale drawings are required for finding dimensions while doing measurements.
Following drawings are required
PLAN -AT A SCALE OF 1 CM = 1 METRE
ELEVATION AND SECTIONAL ELEVATION -AT A SCALE OF 1 CM = 1 METRE
ETAILED DRAWINGS -AT A SCALE OF 1 CM = 20 CM
SPECIFICATION
GENERAL SPECIFICATIONS
DETAILED SPECIFICATIONS
RATES
Rates per unit of various items of work include
a. The rate of various materials which are used in
construction
b. Labour wages and categories
c. Location of work its distance from source of material and cost of transport
Rates can be obtained from P.W.D. schedule of rate book or can be calculated by “ Analysis of Rates” method.
ESTIMATE
IN PUTS | PROCESS | OUT PUTS |
DRAWING | CALCULATION OF | REPORTS |
SPECIFICATION | LABOUR (SKILLED, UNSKILLED) | PRELIMINARY ESTIMATE |
RATES | MATERIAL (Course FINE) | OR |
CARRAIGES | DETAIL ESTIMATE |
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