Types of Estimate

Types of Estimate

Estimating is an essential aspect of quantity surveying and costing. It involves determining the approximate costs and quantities of materials, labor, and resources required for a construction project. Estimates play a crucial role in project planning, budgeting, and decision-making. In this topic, we will explore the different types of estimates used in the construction industry.

I. Introduction

Estimating is a fundamental process in quantity surveying and costing. It involves predicting the costs and quantities of materials, labor, and resources required for a construction project. Estimates are essential for project planning, budgeting, and decision-making. They help in determining the feasibility of a project and assist in resource allocation.

A. Importance of estimating in quantity surveying and costing

Estimating is crucial in quantity surveying and costing for several reasons:

1. Project Planning: Estimates provide a basis for project planning by determining the resources required and their associated costs.
2. Budgeting: Estimates help in developing accurate budgets for construction projects.
3. Decision-making: Estimates assist in making informed decisions regarding project feasibility, resource allocation, and cost control.

B. Fundamentals of estimating

Before diving into the types of estimates, let's understand the fundamentals of estimating:

1. Definition of estimate: An estimate is an approximation of the quantities and costs of materials, labor, and resources required for a construction project.
2. Purpose of estimating: The primary purpose of estimating is to determine the approximate costs and quantities involved in a construction project.
3. Role of estimates in project planning and budgeting: Estimates provide the foundation for project planning and budgeting by determining the resources required and their associated costs.

II. Estimates for Different Projects

Different types of estimates are used for different types of projects. Two commonly used types of estimates are:

A. Plinth Area Rate

The plinth area rate is a method of estimating the cost of a building based on its plinth area. The plinth area is the total built-up area of a building at the floor level. This method is suitable for residential and commercial buildings.

1. Definition and explanation

The plinth area rate is the cost per unit area of the plinth area. It is calculated by dividing the total cost of construction by the total plinth area of the building.

2. Calculation method

The plinth area rate can be calculated using the following formula:

Plinth Area Rate = Total Cost of Construction / Total Plinth Area

3. Application and suitability for different types of buildings

The plinth area rate method is suitable for residential and commercial buildings where the cost of construction is directly proportional to the built-up area.

4. Advantages and disadvantages

Advantages of the plinth area rate method include:

• Simple and easy to understand
• Suitable for residential and commercial buildings

Disadvantages of the plinth area rate method include:

• Does not consider the complexity of the design
• May not be accurate for buildings with irregular shapes or non-standard features

B. Cubical Content Rate

The cubical content rate is a method of estimating the cost of a structure based on its volume. This method is suitable for structures such as bridges, dams, and tanks.

1. Definition and explanation

The cubical content rate is the cost per unit volume of the structure. It is calculated by dividing the total cost of construction by the total volume of the structure.

2. Calculation method

The cubical content rate can be calculated using the following formula:

Cubical Content Rate = Total Cost of Construction / Total Volume of the Structure

3. Application and suitability for different types of structures

The cubical content rate method is suitable for structures where the cost of construction is directly proportional to the volume, such as bridges, dams, and tanks.

4. Advantages and disadvantages

Advantages of the cubical content rate method include:

• Suitable for structures with irregular shapes or non-standard features
• Takes into account the volume of the structure

Disadvantages of the cubical content rate method include:

• More complex calculation method
• May not be accurate for structures with complex designs or unique features

III. Types of Estimates

In addition to the plinth area rate and cubical content rate, there are several other types of estimates used in the construction industry. These include:

A. Preliminary Estimate

The preliminary estimate is an initial estimate prepared at the early stages of a project. It helps in determining the feasibility of the project and assists in project initiation and feasibility studies.

1. Definition and purpose

The preliminary estimate is an approximate estimate prepared based on limited information available at the early stages of a project. Its purpose is to provide a rough idea of the project cost and assist in project initiation and feasibility studies.

2. Components and factors considered

The preliminary estimate takes into account various components and factors, including:

• Site investigation and survey
• Preliminary design and drawings
• Cost of materials and labor
• Contingencies and allowances

3. Importance in project initiation and feasibility studies

The preliminary estimate is crucial in project initiation and feasibility studies as it helps in determining the feasibility of the project and assists in making informed decisions regarding project viability.

4. Real-world examples and applications

Real-world examples of preliminary estimates include:

• Estimating the cost of a new residential development based on initial site survey and design
• Estimating the cost of a new bridge based on preliminary design and drawings

B. Original Estimate

The original estimate is a detailed estimate prepared at the beginning of a project. It serves as the baseline for project planning and budgeting.

1. Definition and purpose

The original estimate is a comprehensive estimate prepared based on detailed information available at the beginning of a project. Its purpose is to provide an accurate estimate of the project cost and serve as the baseline for project planning and budgeting.

2. Factors and considerations in preparing the original estimate

The original estimate takes into account various factors and considerations, including:

• Detailed design and drawings
• Quantity takeoff of materials
• Labor rates and productivity
• Equipment and machinery costs
• Contingencies and allowances

3. Role in project planning and budgeting

The original estimate plays a crucial role in project planning and budgeting as it provides an accurate estimate of the project cost and serves as the baseline for developing project schedules and budgets.

4. Step-by-step walkthrough of preparing an original estimate

The process of preparing an original estimate involves the following steps:

1. Gather detailed design and drawings
2. Perform quantity takeoff of materials
3. Determine labor rates and productivity
4. Calculate equipment and machinery costs
5. Add contingencies and allowances
6. Sum up all the costs to obtain the total project cost

C. Revised Estimate

The revised estimate is an updated estimate prepared during the course of a project. It takes into account changes and variations that occur during the construction process.

1. Definition and purpose

The revised estimate is an updated estimate prepared to reflect changes and variations that occur during the construction process. Its purpose is to provide an accurate estimate of the project cost considering the changes and variations.

2. Factors and considerations in revising the estimate

The revised estimate takes into account various factors and considerations, including:

• Changes in design and scope
• Variations in quantities of materials
• Changes in labor rates and productivity
• Additional costs and expenses

3. Importance in project changes and variations

The revised estimate is crucial in managing project changes and variations as it helps in assessing the impact of changes on the project cost and assists in making informed decisions regarding project modifications.

4. Real-world examples and applications

Real-world examples of revised estimates include:

• Estimating the cost of additional work requested by the client
• Estimating the cost of design changes during the construction process

D. Supplementary Estimate

The supplementary estimate is an additional estimate prepared to account for unforeseen circumstances and additional work that arises during the course of a project.

1. Definition and purpose

The supplementary estimate is an additional estimate prepared to account for unforeseen circumstances and additional work that arises during the course of a project. Its purpose is to provide an accurate estimate of the additional costs and assist in project cost control and management.

2. Factors and considerations in preparing the supplementary estimate

The supplementary estimate takes into account various factors and considerations, including:

• Unforeseen circumstances and events
• Additional work requested by the client
• Changes in material prices and availability
• Changes in labor rates and productivity

3. Role in project cost control and management

The supplementary estimate plays a crucial role in project cost control and management as it helps in assessing the additional costs and assists in making informed decisions regarding project modifications and resource allocation.

4. Advantages and disadvantages

Advantages of the supplementary estimate include:

• Provides an accurate estimate of additional costs
• Helps in project cost control and management

Disadvantages of the supplementary estimate include:

• Increases the overall project cost
• Requires additional time and effort to prepare

IV. Conclusion

In conclusion, estimating is a fundamental process in quantity surveying and costing. It involves determining the approximate costs and quantities of materials, labor, and resources required for a construction project. Different types of estimates, such as the plinth area rate, cubical content rate, preliminary estimate, original estimate, revised estimate, and supplementary estimate, are used in the construction industry. Each type of estimate serves a specific purpose and plays a crucial role in project planning, budgeting, and decision-making. Understanding the different types of estimates and their applications is essential for professionals in the construction industry.

Summary

Estimating is an essential aspect of quantity surveying and costing. It involves determining the approximate costs and quantities of materials, labor, and resources required for a construction project. Different types of estimates, such as the plinth area rate, cubical content rate, preliminary estimate, original estimate, revised estimate, and supplementary estimate, are used in the construction industry. Each type of estimate serves a specific purpose and plays a crucial role in project planning, budgeting, and decision-making.

Analogy

Estimating can be compared to planning a road trip. Before embarking on a journey, you estimate the distance, fuel consumption, and other expenses to determine the feasibility and plan your budget. Similarly, in construction projects, estimating helps in determining the costs and quantities of materials, labor, and resources required for a project, assisting in project planning and budgeting.