Hello there, Welcome In today's post, you will learn about the many construction estimating approaches, such as the Long Wall - Short Wall Method and the Center Line Method.
You will explore the approaches mentioned above to develop estimates in depth.
So, let's get started.
Estimation of Building.
Estimation is the art of calculating the quantities and costs of different materials used in a building before its construction.
The first type of building estimate is known as a rough cost estimate.
This estimate will not describe the exact cost of the building, but it will provide you with an approximate cost value that will help you manage money for the installation.
Rough Cost Estimation is carried out in various ways for various types of buildings.
Before beginning any project, an estimate of its fruitfulness and cost is made.
Rough cost estimation is done in different ways for different types of projects.
The Detailed Cost Estimate is another well-known method of building estimation.
Each project item is determined and multiplied by its unit of rate to obtain the cost in this method of building estimation.
The Detailed Estimate includes every cost type. As a result, it is thought to be a better estimation method.
A detailed Estimate is performed to obtain Technical Sanction approval for the related project.
Technical Terms used in Building Estimation.
Different Technical terms are used for making building estimate. A few essential technical terms are described below.
1. Plinth Area.
The plinth area is the built area above the floor surface. It also includes the veranda and other passageways with a roof over them.
The area of the plinth is measured up to the outer edges of the walls.
2. Floor Area.
The internal area of all rooms is included in the floor area. A kitchen, bathroom, and stairwell are among the rooms. It excludes any area surrounded by walls.
3. Carpet Area.
The carpet Area is the size of a residential room. It does not include the kitchen, bathroom, or stairwell.
4. Market Rate.
Market Rate is the per-unit price of various marketable objects. It also includes conveyance charges, waste charges, and object taxes.
5. Schedule of Rates.
Engineering departments prepare rates for payments based on market rates, which are known as the Schedule of Rates.
It includes cement, sand, gravel, and steel bar rates, among other things. However, it also displays labor or material rates.
Labor rates are also known as wage rates. Composite Rates, abbreviated as C.S.R., are labor and material rates combined.
A rate schedule is issued regularly, taking into account market rate fluctuations.
It is issued at the beginning of each year and is valid for at least three months. Which is known as the Market Rates Schedule, which is uploaded to the Internet and abbreviated as M.R.S.
6. Premium.
Rates are subject to increase even after the Schedule of Rates is issued, which is why additional rates are agreed upon during the agreement with the contractor.
This is referred to as Premium.
7. Rebate.
The rebate is subject to reduction even after the Schedule of Rates is published.
Reduced rates are agreed upon during the Rebate agreement with the contractor.
8. Contingencies.
Estimates will include some items that are not listed under specific headings.
3 to 5% of the overall budget is set aside to cover the cost of these items, known as Contingencies Charges.
9. Petty Items.
Certain items cannot be precisely determined during the estimate preparation process.
These are referred to as Petty Items.
10. Bill of Quantity.
A bill of quantity is a list of the items of work. This statement will include item names, a description of the work, and the quantity of work.
However, the contractor leaves empty cells for related rates and amounts submitted as B.O.Q.
Once the rates and amounts are filled in, this statement will be known as the Abstract of Cost.
11. Capital Cost.
The total cost paid out throughout the project is the capital cost.
Construction costs include survey costs, design and supervision costs, water supply costs, sanitary costs, electrification costs, gasification costs, and plot price costs, among other things.
12. Prime Cost.
The amount is set aside during the estimation process and will be spent on specific items with the approval of the owner, project manager, or site engineer.
It may include payments for door and window fittings, water supply, and sanitary and electrical fittings, among other things.
This is referred to as the Prime Cost.
13. Provisional Sum.
During the preparation of the estimates, an amount is set aside to cover undetermined items.
This is known as a Provisional Sum, and it includes the cost of installing telephones, gas, or Internet, as well as installing air conditioners or lifts, among other things.
14. Work Charge Establishment.
Staff is temporarily enlisted during the project's construction, known as Work Charge Establishment.
This staff consists of secretaries, mates, and security guards, among other things.
They are only enlisted for a limited time. Their salaries or wedges are paid 1.5 to 2 percent of the total cost.
15. T. and P. Charges.
During the estimation process, 1 to 1.5 percent of the total cost is set aside for tools and giants, known as T. and P. Charges.
T. represents Tools, and P. represents Plants.
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Methods of Estimation of Building.
Estimation of a building can be done by different methods as follow.
So, Let's discuss the methods of estimation of the building.
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1. Longwall – Short wall Method.
The external wall along the room's length is designated as the Longwall, while the wall perpendicular to the Longwall is designated as the Short wall.
First, determine the length of a long or short wall and its center-line lengths.
The length of the long wall (from end to end) can then be measured by adding half a width at each end to its center-line length.
Thus, the length of a short wall is measured into in and may be calculated by subtracting half of its center-line length at each end.
The short wall's length normally grows from Earthwork to brickwork in the superstructure, while the long wall's length reduces.
To get amounts, multiply these lengths by depth and breadth.
The wall along the room's length is regarded as a long wall in the short wall and long wall approach, whereas the wall perpendicular to a long wall is known as a temporary wall.
2. Center Line Method.
The Center Line technique of estimating takes measurements of the wall up to the center. In most cases, internal measures are taken.
Internal measurements of the thickness of one-half wall and the thickness of the other half wall are summed to establish the length of the room walls' Center Line.
If all of the steps are symmetrical in the wall's cross-section, the total length of the Center Line will be uniform for all wall elements.
If these steps are not symmetrical, each step's length will be computed independently.
Regardless of whether the wall design is consistent throughout the building, determining the length of the Center Line is simple.
The Center Line method is easily applied to circular and polygonal structures.
Despite this, this method is also appropriate for use in small buildings with few rooms.
3. Crossing Method.
If the thickness of the external walls is the same as the thickness of the overall building and the thickness of the internal walls is also the same, they are not the same.
This method is then used for estimating.
In such cases, the center line method is used for external walls, and the long-short wall method is used for internal walls.
Estimation of Single storied residential building with several rooms (load-bearing type structure)
Let's take a practical problem of a building to understand the concepts more clearly and faster technique for calculation. Here, we will only determine Earthwork in excavation and brickwork in the foundation.Center-line lengths foundation details of the building with are shown in the drawing.
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C/C length of short wall (SW) = 4*3.0 + 2*2.5 = 17.0 m
Number of T junctions in the drawing (J) = 4
Total length (L) = LW + SW - J*(breadth/2)
From the foundation drawing, the breadth of the foundation = 0.625 m, and the depth of the foundation = 0.60 m
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Sir, you are sharing your best knowledge about civil engineering, specifically building construction.
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