How to make an estimate?

Estimate

Before understanding the construction of a project, it is necessary to know the probable cause required to complete the proposed work.

Does an estimate for any construction work may be defined as the process of calculating the quantities and cost of the various items required in their connections with the outcome.

The estimate is prepared by calculating the quantities from the dimensions on the drawing for the various items required to complete the project and multiplied by the unit cost of the article concerned.

An estimate of a project is, therefore, a forecast of its probable cost.

QUANTITY SURVEYING

For any construction work, calculating the quantities of various items of work is called quantity surveying.

COSTING

the process of determining the probable cost of the project after knowing the amounts of various objects and their unit rate is called costing.

Data required for preparing an estimate

1. Plan, elevation, section
2. Specifications
3. Item rates

Plans, hills, and section

From the plans, elevations, and sections of the building, quantities of various items are calculated.

Specifications

An Engineering specification provides detailed descriptions of all artistry and materials required to complete the project by its drawing and details.

Specifications of the total cost of the project. If specification demand for high-quality artistry, the cost of the project will increase.

Item rates

To prepare an estimate, the rate of various items into,lved in the project is required.

cost of an item =to the quantity of item × rate for items

The rate of an object depends on various factors that are:

• material cost
• labor cost
• machinery cost
• transportation cost
• overhead charges
• contractors profit etc.

Types of estimate

1. Approximate estimate or preliminary estimate
2. Detailed estimate
3. Quantity estimate
4. Revised estimate
5. Supplementary estimate
6. The supplementary and revised estimate
7. Annual repair or maintenance estimate

Qualities of a good estimator

1. He must possess the ability to read and interrupt drawings accurately and efficiently.
2. He must have construction experience in the field
3. He must know Constructions rules and regulations
4. He must have good knowledge of measurement and simple trigonometry
5. He must have her understanding of construction methods and procedures materials of construction labor problems specifications etc.
6. He must have good knowledge of the measurement of various items of construction.
7. He must possess accuracy in calculations and cost
8. He must have good general knowledge
9. He must possess excellent Personal qualities such as common sense, skills, experience, foresight, good judgment, etc.

Duties of a reasonable quantity surveyor or estimator

1. To prepare an estimate
2. To prepare specifications
3. To survey buildings and land
4. To carry out rate analysis
5. To finalize the final accounts
6. To supervise engineering structure during execution.
7. To prepare a work execution schedule
8. To work as an arbitrator
9. To carry out valuations of the property
10. To advise the architect and the local authorities but estimate the cost of the project and the construction of the structure

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For actual cost exceeding the estimated cost

1. Proper care is not taken while preparing an estimate.
2. Increase in material rates and labor charges after preparation of estimate.
3. It is missing some items while preparing an estimate.
4. Change in design during the execution of work.
5. Increase in the depth of the foundation during execution.

Methods of preparing an approximate estimate

1. Service unit method
2. Plinth area method
3. Floor area method
4. Carpet area method
5. Percentage method
6. Cubical content method
7. Typical bay method
8. Empirical equations of C.B.R.I
9. Approximate quantities method
10. Cost comparison method