An estimate is an anticipated or probable amount of construction which is usually made before the execution of the actual construction work.
Estimation is the scientific way of working out the appropriate amount of engineering project prior to the execution of work.
It is important to note that estimated amount may be different from the actual cost of the project. Estimated amount should not be differ than 5% to 10% of the actual cost of the project.
Estimation requires thorough knowledge of construction procedure, labor and material. It requires knowledge of drawing specifications and prevailing market rates.
Need for an estimate
The main purpose of an estimate is to know the probable amount before the work is executed.
The actual cost is always obtained after the completion of project. If the estimate is carried out with lot of accuracy. Then the actual cost will be near to the estimated amount. That is the reason why experienced person is employed for this purpose.
Estimate of a project will help us in following ways.
- It tells whether the project is suitable or not by considering the cost comparison.
- The quantity of major components of the project like cement, bricks, steel, sand etc and their cost to be entered by considering the prevailing market rates.
- It helps to invite tenders.
- It helps to monitor the contractor payment record.
- We can also check the contractor work being executed.
- It helps to experience the details of work to be executed.
- It helps to foresee the minor and major components of the project.
- Estimate will serve as the basis for developing job costing system.
- It will help to build construction schedule before execution.
Job costing system compares actual cost of project at specific time for particular item of estimate. This date tells which item needs more cost control during construction process.
- It helps to find out duration of work of various activities for construction schedule.
Duration of work = magnitude of work / standard output
- The essence of an estimate consists of forecasting future events in construction process. Then placing currency value on those events. Many additional factors can also affect the future events of construction.For example
- labor production
- material availability
- financial markets
- weather conditions
- construct ability issues
- equipment availability
- contract types
- quality issues
- project control system