Different Types Of Estimates:
There are different types of estimates which are as follows:
1. Preliminary Or Approximate Or Rough Estimate:
This is an inexact estimate to find out a rough cost in a short time which enables the authority concerned to consider the financial aspect of the scheme, for according sanction to the same.
Such an estimate is framed after knowing the rate of similar works and from practical knowledge in various ways for various types of works such as:
- Plinth area or square-meter method,
- Cubic rate or cubic meter method,
- Service until or until rate method,
- Bay method,
- Aproximate quantities with bill method,
- Cost comparison method,
- The cost of materials and labor.
2. Detailed Estimates:
This consists of detailed particulars of the quantities, rates, and costs of all the materials required for satisfactory completion of a project.
Quantities of all materials of work are calculated according to their respective dimensions on the drawings on a measurement sheet.
Multiplying these quantities by their respective rates in a separate sheet, the cost of all items of work are figured out individually and then summarized, i.e abstracted (which is the detailed actual estimated cost of work).
All other expenses required for satisfactory completion of the project are added to the above cost to frame the total of a detailed estimate.
A detailed estimate is accompanied by
- Detailed drawings showing plans, different sections, Key or Index plan etc.
- Design data and calculations
- The basis of rates adopted in the estimate.
Such a detailed estimate is prepared for technical sanction, administrative approval and also for the execution of a contract with the contractor.
3. Quantity Estimates Or Quantity Survey:
This is a complete estimate or list of quantities for all materials of work required to complete the concerned project.
The quantity of each individual item of work is worked out from respective dimensions on the drawing of the structure.
To find the cost of an item its quantity is multiplied by the rate per unit for that item.
The purpose of the bill of quantities is to provide a complete list of quantities necessary for the completion of any engineering project and when priced gives the estimated cost of the project.