Estimation and Costing

 INTRODUCTION TO THE SUBJECT

DEFINITION OF ESTIMATING AND COSTING

Estimating is the technique of calculating or Computing the various quantities and the expected Expenditure to be incurred on a particular work or project.

In case the funds available are less than the estimated cost the work is done in part or by reducing it or specifications are altered, the following requirement are necessary for preparing an estimate.

a ) Drawings like plan, elevation and sections of important points.

b)Detailed specifications about workmanship & properties of materials etc.

c)Standard schedule of rates of the current year.

NEED FOR ESTIMATION AND COSTING

1.Estimate give an idea of the cost of the work and hence its feasibility can be determined i..e whether the project could betaken up with in the funds available or not.

2.Estimate gives an idea of time required for the completion of the work.

3.Estimate is required to invite the tenders and Quotations and to arrange contract.

4.Estimate is also required to control the expenditure during the execution of work.

5.Estimate decides whether the proposed plan matches the funds available or not.

PROCEDURE OF ESTIMATING OR METHOD OFESTIMATING.

Estimating involves the following operations

1.Preparing detailed Estimate.

2.Calculating the rate of each unit of work

3.Preparing abstract of estimate

DATA REQUIRED TO PREPARE AN ESTIMATE

1.Drawings i.e. plans, elevations, sections etc.

2.Specifications.

3.Rates.

1.4.1 DRAWINGS

If the drawings are not clear and without complete dimensions the preparation of estimation become very difficult. So, It is very essential before preparing an estimate.

SPECIFICATIONS

a) General Specifications: This gives the nature, quality, class and work and materials in general terms to be used in various parts of wok. It helps no form a general idea of building.

b) Detailed Specifications: These gives the detailed description of the various items of work laying down the Quantities and qualities of materials, their proportions, the method of preparation workmanship and execution of work.

RATES:

For preparing the estimate the unit rates of each item of work are re-quired.

1. For arriving at the unit rates of each item.

2. The rates of various materials to be used in the construction.

3. The cost of transport materials.

4. The wages of labour, skilled or unskilled of masons, carpenters, Mazdoor, etc.,

COMPLETE ESTIMATE:

Most of people think that the estimate of a structure includes cost of land, cost of materials and labour, But many other direct and indirect costs included and is shown below.

LUMPSUM:

                While preparing an estimate, it is not possible to workout in detail in case of petty items. Items other than civil engineering such items are called lumpsum items or simply L.S. Items.

The following are some of L.S. Items in the estimate.

    1. Water supply and sanitary arrangements.

    2. Electrical installations like meter, motor, etc.,

    3. Architectural features.

    4. Contingencies and unforeseen items.

                In general, certain percentage on the cost of estimation is allotted for the above L.S. Items

Even if subestimates prepared or at the end of execution of work, the actual cost should not exceed the L.S. amounts provided in the main estimate.

WORK CHARGED ESTABLISHMENT:

            During the construction of a project considerable number of skilled supervisors, work assistance, watch men etc., are employed on temporary basis. The salaries of these persons are drawn from the L.S. amount alloted towards the work charged establishment. that is, establishment which is charged directly to work. an L.S. amount of 1½ to 2% of the estimated cost is provided towards the work charged establishment.

EXERCISE

Short Answer Questions

    1. State the requirements of an estimate?

    2. Briefly Explain need for estimation?

    3. What is work charged establishment?