ESTIMATION IN INTERIOR DESIGNING

Defination: Estimation is a tool for planning and controlling the construction activity of any project with respect to quality, time and finance.

Estimation: There are two things involved in construction quality and quantity, these two things lead to govern the estimate of the work. By calculating quantity required and quality of that material you can find estimation.

Quantity can be find through the study and analyses of drawing which is prepared with respect to the design of the project.Thus the quantity decides the quantum of work involved in the construction and it help in finding out the quantities of various material required as well as the total labour necessary for the work.

Quality is governed through specifications for material and workmanship.

Estimation is a forecast of probable cost of any project. Before undertaking any work or project it is necessary to know the probable cost of the project which was found by the estimation. The primary object of an estimation is to enable to know the cost of work before the work start. The actual cost is known only after the work completed.

If estimate is prepared carefully and correctly by the person (estimator) who is experienced and fully know the method of work, then there will not be much difference between estimated cost and actual cost of the project.

The estimation is prepared by calculating the quantities required and then calculating the cost at suitable rates , to get the approximate cost of the projet. Provision of contingencies, 3% to 5% of the estimated cost, is made in the estimate to cover the miscellaneous expenditures which do not come under any item of work. Also added the work charged establishment at 1.55 to 2% of the estimated cost. The cost of the preliminary works and surveying, cost of land including cost of acquisition, cost of leveling and dressing of ground and the cost of other external services are required to be provided in the estimation besides the estimated cost of the different items of the main work. Provision for supervision of departmental charges 5 to 10% of the estimated cost is also made to get the estimated cost of the whole project.

The process of preparing an estimate is known an estimating and it includes two steps

• Taking out quantities
• Abstracting

Taking Out Quantities: The details of measurements of each item of work are taken out correctly form plan and drawings and quantities under each item are calculated in a tabular form named as details of measurement form as follows:

Item No.	Description or Particulars	No.	Length	Breadth	Height or Depth	Content or Quantity

Abstract Of Estimated Cost: The cost of each item of work is calculated in a tabular form from the quantities already computed and total cost is worked out in abstract of estimate form as shows below

Item No.	Description or Particulars	Quantity	Unit	Rate	Amount

Types Of Estimation:

1. Preliminary Estimate
2. Plinth Area Estimate
3. Cube Rate Estimate
4. Approximate Quantity Method Estimate
5. Detailed Estimate
6. Revised Estimate
7. Supplementary Estimate
8. Annual Repair or Maintenance Estimate

1. Preliminary Estimate:

It is also called as Approximate estimate or Abstract estimate or Rough cost estimate. It is required for studies of various aspects of a work to decide the financial position before the work starts. In such project which gives revenue income, income will be calculated and preliminary estimate is formed, by comparing this calculation it may be seen whether the investment on the work is justified or not.

2. Plinth Area Estimation:

This is a approximate estimation. This is prepared on the basis of plinth area of building, the rate being deduced from the cost of renovation of similar building having similar specification. Plinth area estimate is calculated by finding the plinth area of the building and multiplying by the plinth area rate. The plinth area should be calculated for the covered area by taking external dimensions of the building at the floor level. Courtyard and open spaces should not be included in this.

3. Cube Rate Estimation:

Cube rate estimation is a approximate estimation. It is prepared on the basis of cubical content of the building. This is calculated by finding the cubical contents length x breath x height and multiplied by cube rate. It is similar as plinth area but more accurate than plinth area estimate as height is also calculated.

4. Approximmate Quantity Method estimation:

In this method approximate total length of walls is calculated in running metre and its total length is multiplied with rate per running metre of wall. The running metre cost for structure and the interior should be calculated first and these running metre rates should be multiplied by the total length of the walls.

5. Detailed Estimation:

Detail estimate consists of working the quantities of each item of work and there working cost. Length, breadth, and height are taken out correctly and quantities of each item are taken out correctly from drawing and quantities of each item are calculated and biling are done.

Item No.	Description	No.	Length	Breadth	height	Quantity

By this chart Quantity of each item find detail of each item properly is necessary.

Item No.	Description	Quantity	Unit	Rate	Amount

After finding proper quantities there units put the value in this chart by applying proper rate of particular item you can find the amount. by adding your fees charges and other charges according to requirement of work the final estimation will be find.

6. Revised Estimate:

It is accurate estimate and is prepared when the original sanctioned estimate is exceeded by more than 5 %. Or expenditure on the work exceeds the amount of administrative sanction by more than 10%. Or material deviation from original proposal attached by statement showing the variation of each item.

7. Supplimentry Estimate:

It is a accurate estimate and is prepared when additional work are required. This is fresh detailed estimate of the additional work that can be during progress of work or further work after completing your previous work.

8. Annual Repair or Maintanance Estimate:

It is accurate estimate and is prepared to maintain the structure in proper order and safe condition. It include white washing, color washing, painting, minor repair etc.

9.  Supplementary and revised estimate: 

When a work is partially abandoned and the estimated cost of the remaining work is less than 95% of the original work, that is less than 95% of the original sanctioned estimate, or when there are material deviations and changes in the design which may cause substantial saving in the estimate, then the amount of the original estimate is revised by the competent authority. A supplementary and revised estimate is then prepared and fresh technical sanction of the competent authority is obtained.

If at any time either before or during the execution of original work, it is found that the original estimate is excessive, and then divisional officer may sanction a revised other higher authorities are informed.