Estimation and costing in civil engineering is one of the most important subjects. It helps engineers calculate the quantity of materials, labour cost, and total project cost before starting construction work. Proper estimation and costing ensure that construction projects are completed within budget and without material shortage. Every civil engineer, diploma student, and site supervisor must have good knowledge of estimation and costing.
What is estimation in civil engineering?
Estimation is the process of calculating the quantity of materials and labour required for construction work. It helps in determining how much cement, sand, steel, bricks, and other materials are needed for a project. Estimation also helps in calculating the total cost of construction before starting the project.
Estimation is done based on drawings and specifications of the building. It plays a very important role in planning and execution of construction work.
What is costing?
Costing is the process of calculating the total cost of construction work. It includes cost of materials, labour charges, equipment cost, transportation, and other expenses. Costing helps in preparing the budget for construction projects.
Without proper costing, construction projects may face financial loss and delays. Costing ensures that the project is completed within the planned budget.
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Importance of estimation and costing in civil Engineering
Estimation and costing are very important for successful completion of construction projects. It provides many advantages:
- Helps in planning construction work
- Determines total project cost
- Helps in material procurement
- Avoids wastage of materials
- Helps in tender process
- Controls project budget
- Ensures proper management
Proper estimation and costing help engineers to complete projects efficiently and economically.
Types of estimates in civil engineering
There are different types of estimates used in construction projects depending on project stage and requirements.
Preliminary estimate
Preliminary estimate is prepared at the initial stage of project planning. It gives an approximate cost of construction based on plinth area or cubic rate. It helps the owner to decide whether the project is feasible or not.
Detailed estimate
Detailed estimate is prepared using detailed drawings and specifications. It includes exact quantity and cost of each material required for construction. Detailed estimate is prepared before starting construction work.
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Revised estimate
When the cost of project increases due to changes in design or material rates, revised estimate is prepared. It shows the updated cost of the project.
Supplementary estimate
Supplementary estimate is prepared when additional work is added to an existing project. It includes cost of extra items not included in original estimate.
What is BOQ (Bill of Quantities)?
BOQ stands for Bill of Quantities. It is a document that contains detailed quantity of materials and cost required for construction work. BOQ is used for tendering and billing purposes. Contractors use BOQ to quote rates for construction work.
BOQ helps in comparing contractor quotations and selecting the best contractor for the project.
What is rate analysis?
Rate analysis is the process of determining cost per unit of work. It includes material cost, labour cost, equipment charges, transport cost, and contractor profit. Rate analysis helps in fixing the rate of construction items like brickwork, plastering, concrete, and excavation.
Proper rate analysis helps in accurate costing and budgeting of construction projects.
Methods of estimation
There are different methods used for estimation in construction:
Centre line method
In this method, total centre line length of walls is calculated to find quantity of excavation and masonry work. It is suitable for symmetrical buildings.
Long wall and short wall method
In this method, length of long walls and short walls is calculated separately to determine quantity of work. It is commonly used for building estimation.
Plinth area method
Plinth area method is used for approximate cost calculation. Cost is calculated based on plinth area of building and rate per square meter.
What is contingency in estimation?
Contingency is an extra amount added in estimation to cover unexpected expenses during construction. Usually 3% to 5% of total cost is added as contingency. It helps in managing unforeseen costs.
Factors affecting construction cost
Construction cost depends on many factors:
- Quality of materials
- Labour charges
- Location of project
- Transportation cost
- Design complexity
- Market rate of materials
Engineers must consider all these factors while preparing estimation and costing.
Tips for accurate estimation
To prepare accurate estimation and costing, follow these tips:
- Study drawings carefully
- Use correct formulas
- Check material rates
- Include labour cost
- Add contingency amount
- Avoid calculation mistakes
Accurate estimation helps in smooth execution of construction projects without financial problems.
Conclusion
Estimation and costing in civil engineering is essential for planning and execution of construction projects. It helps in calculating material quantity, total cost, and project budget. Every civil engineer and diploma student should have strong knowledge of estimation and costing. Proper estimation ensures quality construction, cost control, and successful completion of projects.
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