How to prepare a detailed Estimate

How to prepare a detailed Estimate
The preparation of detailed estimate consists of working out quantities of various items of work and then determines the cost of each item. This is prepared in two stages:

Details of measurements and calculation of quantities
The complete work is divided into various items of work such as earth work concreting, brick work, R.C.C. Plastering etc., The details of measurements are taken from drawings and entered in respective columns of prescribed proforma. The quantities are calculated by multiplying the values that are in numbers column to Depth column as shown below:

Measurement form.png

Abstract of Estimated Cost :
The cost of each item of work is worked out from the quantities that already computed in the details measurement form at workable rate. But the total cost is worked out in the prescribed form is known as abstract of estimated form. 4% of estimated Cost is allowed for Petty Supervision, contingencies and Unforeseen items. A percentage of 1.5% to 2% is also added to meet the expenditure of work-charged establishment. The grand total thus obtained is estimated cost of the work.
abstract form.png

The detailed estimate should be accompanied with:
Report, specification, Drawings (plans, elevations, sections), designs charts and calculations, standards schedules of rates.

Factors to be considered During Preparation of Detailed Estimate
Quantity and transportation of materials:

For bigger project, the requirement of materials is more. Such bulk volume of materials will be purchased and transported definitely at cheaper rate.
Location of site:
The site of work is selected, such that it should reduce damage or in transit during loading, unloading, stocking of materials.
Local labour charges:
The skill, suitability and wages of local labors are considered while preparing the detailed estimate.
Units of dimensions for materials and works and mode of measurement for different items of works and materials.

UNITS OF MEASUREMENTS:

  • Single units work like doors, windows, trusses etc., is expressed in numbers.
  • Works consists linear measurements involve length like cornice, fencing, hand rail, bands of specified width etc., are expressed in running meters (RM)
  • Works consists area surface measurements involve area like plastering, white washing, partitions of specified thickness etc.
  • Works consist of cubical contents which involve volume like earth work, cement concrete; Masonry etc. are expressed in Cubic meters(m3)(cu m).


The units of measurements are mainly categorized for their nature, shape and size and for making payments to the contractor.
The principle of units of measurements normally consists the following:

Single units work like doors, windows, trusses etc., is expressed in numbers.
Works consists linear measurements involve length like cornice, fencing, hand rail, bands of specified width etc., are expressed in running meters (RM)
Works consists area surface measurements involve area like plastering, white washing, partitions of specified thickness etc.
Works consist of cubical contents which involve volume like earth work, cement concrete; Masonry etc. are expressed in Cubic meters(m3)(cu m).