Estimating is the technique of calculating or computing the variousquantities and the expected Expenditure to be incurred on a particular work orproject. In case the funds available are less than the estimated cost the work isdone in part or by reducing it or specifications are altered, the following requirementare necessary for preparing an estimate.
1. Drawings like plan, elevation and sections of important points.
2. Detailed specifications about workmanship& properties of materials etc.
3. Standard schedule of rates of the current year.
UNITS OF MEASUREMENTS
The units of measurements are mainly categorized for their nature, shape and size and for making payments to the contractor and also. The principle of units of measurements normally consists the following:
a) Single units work like doors, windows, trusses etc., is expressed in numbers.
b) Works consists linear measurements involve length like cornice, fencing, hand rail, bands of specified width etc., are expressed in running meters (RM)
c) Works consists areal surface measurements involve area like plastering, white washing, partitions of specified thickness etc., and are expressed in square meters
Works consists cubical contents which involve volume like earth work, cement concrete, Masonry etc are expressed in Cubic metres.
RULES FOR MEASUREMENT
The rules for measurement of each item are invariably described in IS- 1200. However some of the general rules are listed below.
1.Measurement shall be made for finished item of work and description of each item shall include materials, transport, labor, fabrication tools and plant and all types of overheads for finishing the work in required shape, size and specification.
2. In booking, the order shall be in sequence of length, breadth and height or thickness
3. All works shall be measured subject to the following tolerances.
I) linear measurement shall be measured to the nearest 0.01m.
II) Areas shall be measured to the nearest 0.01 sq.m
4.Cubic contents shall be worked-out to the nearest 0.01 cum
4. Same type of work under different conditions and nature shall be measured separatelyunder separate items.
5.The bill of quantities shall fully describe the materials, proportions, workmanships and accurately represent the work to be executed.
6.In case of masonry (stone or brick) or structural concrete, the categories shall be measured separately and the heights shall be described:
a) From foundation to plinth level
b) From plinth level to first floor level
c) From Fist floor to second floor level and so on.