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Explain briefly various types of Estimates

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Before undertaking a construction project it is necessary to know the expected cost and it is worked out by estimation. It is a computation of the quantities required and expenditure likely to be in the construction of the work.

The following are the different types of estimates:

1. Preliminary or Approximate Estimate:
This estimate is prepared to decide the financial aspects,policy and to give the idea of the cost of the proposal to the competent sanctioning authority.The calculation for approximate estimate is done in many ways. There are three types of approximate estimate

(a) Unit Rate estimate:
In this method, all the cost of a unit quantity of work such as per kilometer for a highway,per bed of a hospital,per classroom of a school building, per litre for water tank etc are considered first and estimate is prepared by multiplying the cost per corresponding unit by no of units in the structure.

(b) Plinth Area Estimate:
This estimate is prepared if various building are to be considered.It is prepared on the basis of plinth area.Plinth area means length X breadth area of roof portion excluding plinth offset.

(c) Cube Rate Estimate:
It is prepared on the basis of cubic content of the building.Cubic content means plinth area X height of the building.

2. Detailed Estimation:
Since preliminary estimate doesn’t contain broad information about the work,after getting administrative approval on the rough work estimate, detailed estimates are prepared.This includes the quantities and cost of completion of the work.it includes-

(i) Report

(ii) Specification

(iii) Detailed drawings showing plans, elevation, sections etc.

(iv) Design data and calculations

(v) Rates adopted.

3. Annual Repair estimate:
Repairing is done for roads and buildings to keep them in perfect condition. For example,in case of building white washing, oiling,painting,cement plaster repairs,repairing of floors etc. For these type of repairing,annual repair estimates are prepared.In no case,the annual repair amounts should be increased greater than 45% of the capital cost of building.

4. Revised Estimate:
When the sanctioned amount exceeds more than 5% either due to rates being found insufficient or due to some other reasons, a revised estimate is prepared.A comparative statement is attached on the last page.It includes reasons for increase in cost in case of each items. Revised estimate should shows the variation of each items of works, its quantity rate and cost under original and revised.

5. Supplementary Estimate:
While a work is in progress, some additional works may become necessary for the development of the project which was not included when the original estimate was prepared.For this reason,a fresh detailed estimate in addition to the original sanctioned estimate prepared describing the additional work which we called as the supplementary estimate. The abstract of cost should show the amount of original sanctioned estimate as well as the supplementary amount.

6. Complete Estimate:
This is an estimated cost of all items which are related to the work in addition to the detailed estimate.It includes-

(i )The cost of the preliminary works

(ii) The cost of land acquisition and legal expenses.

(iii) Cost of improvement of land

(v) Cost of building of structure

(vi) Cost of temporary accommodation

(vii) Cost of maintenance and repair work

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