10 Methods of Estimation and Costing Works in Civil Engineering Field

1. Preliminary or Rough Cost Estimate:

This is like giving a ballpark figure when someone asks you, "How much will it cost to build a house?" You don’t go into deep details here. You just use general data like cost per square foot and come up with an approximate cost.

Example: If you are asked to estimate the cost of constructing a 3BHK house in Telangana, and the average construction cost is ₹2000 per sqft, and the total area is 1500 sqft, you’d say:
1500 sqft × ₹2000 = ₹30 lakhs (approximate).

2. Plinth Area Method:

This is a slightly detailed version of the preliminary estimate. Here, you calculate the cost based on the plinth area, which means the total built-up area on the ground floor. You multiply the plinth area by the current rates per square foot.

Example: Let’s say a shopping mall is being built in Tamil Nadu with a plinth area of 50,000 sqft, and the rate per sqft is ₹2500. The cost would be:
50,000 sqft × ₹2500 = ₹12.5 crore.

3. Detailed Estimate:

This is the most accurate form of estimation. Here, every single thing is measured, priced, and calculated. You prepare detailed quantities for each item (like bricks, cement, steel, etc.), and then estimate the cost for each one.

Example: For a residential project in Mumbai, you calculate the total number of bricks, bags of cement, steel, tiles, and labor needed for each floor. You add up the cost of materials and labor to get the total.

4. Cube Rate Method:

This is used for multi-storeyed buildings where you calculate the cost based on the total volume (length × breadth × height) of the structure. The total cubic volume is multiplied by the cube rate per cubic meter.

Example: If a high-rise building in Gujarat has a volume of 1,00,000 cubic meters and the cube rate is ₹3000 per cubic meter, the cost would be:
1,00,000 × ₹3000 = ₹30 crore.

5. Item Rate Estimate:

This method breaks down the project into individual items like foundation work, walls, roof, plastering, painting, etc. Each item has its rate, and you calculate the cost for each one and then add them up.

Example: In Kerala, if you are estimating a house and have separate rates for excavation, RCC work, brickwork, plastering, and painting, you’ll estimate the cost for each separately and then total it up.

6. Approximate Quantity Method:

This method is often used for roads or infrastructure projects. You take the approximate quantities of materials like cement, aggregates, bitumen, etc., and multiply them by their unit costs.

Example: For a 5-kilometer road in Maharashtra, you estimate how much aggregate, cement, and bitumen will be required and then multiply by their rates.

7. Unit Rate Method:

This is a method where you calculate the cost per unit of work done. It could be per square foot of a building, per kilometer of road, or per meter of pipeline. The unit rate is multiplied by the number of units to get the total cost.

Example: For a 2 km water pipeline project in Goa, if the rate per meter of pipeline is ₹500, the total cost would be:
2000 meters × ₹500 = ₹10 lakh.

8. Percentage of Project Cost Method:

This is mainly used for professional fees, like an architect or engineer’s fee. You calculate their fee as a percentage of the total project cost.

Example: For a hospital project in Telangana, if the architect’s fee is 5% of the total cost, and the project cost is ₹20 crore, the fee would be:
5% of ₹20 crore = ₹1 crore.

9. Revised Estimate:

This is used when there is a change in the scope of the project or if the original estimate is outdated. The revised estimate includes new prices or additional work.

Example: If a bridge project in Gujarat initially cost ₹50 crore but later changes to ₹55 crore due to increased material costs, the revised estimate reflects this new amount.

10. Supplementary Estimate:

This method is used when additional work is required that wasn’t included in the original plan. It’s like an add-on to the original estimate.

Example: If you’re constructing a school in Tamil Nadu and, halfway through, the client asks for additional classrooms or a parking area, you prepare a supplementary estimate for the additional costs.

Each method of estimation depends on the stage of the project and the level of detail required. For smaller projects, a rough estimate may be enough to start. But for larger projects like highways, buildings, or industrial plants, a detailed estimate or item rate method would be more accurate and reliable.

So, whether you’re working in Maharashtra, Gujarat, or anywhere else, knowing these methods helps you plan and manage the construction budget effectively. Let me know if you want more details on any of these!

Wed Sep 4, 2024