What Is Estimate?
- An estimate is an anticipated or probable cost of job & is generally prepared before the development order is taken up.
- An estimate is actually a computation or calculation or evaluation of the amounts of materials required & expenditure generally included in the development of a structure.
- The original cost is known only after the completion of the job.
- If the estimate is prepared attentively & properly there’ll be least deviation from the estimated cost & the original cost.
- It is essential to realise its probable cost, which might be attained by computing, prior to undertaking the scheme.
- The estimators must be experienced & aware of the design techniques for reliable estimation.
- The estimate can be supplied roughly to know the estimated cost or rough cost.
- The work is disseminated into various modules for an intensive computation, & hence the amounts from each item are measured & also estimated expense is analysed.
- In the budget, allowance towards contingencies, 3-5% of the aggregate expense, is meant to accommodate miscellaneous minor costs.
- The quantities of various materials & labors required can be estimated from a detailed estimate. It additionally denotes a time required for all the job to be performed.
- The price of land & the cost of leveling & dressing the land, as well as other costs must be included within the calculation for the complete estimate.
- To attain the aggregate expense, 5-10% of the estimated cost is paid for supervision or departmental costs.
What Is Actual Cost in Estimate?
Actual cost – The Actual cost of a job is understood after the completion of the job. The account of all expenditure is maintained day to day during the execution of work in the account section & at the end of the completion of the work when the account is completed, the aggregate cost is known.
Types of Estimate
Mainly 8 kinds of cost estimates are given subsequently:-
1. Preliminary Cost Estimate
- The preliminary cost estimate is additionally known as an abstract cost estimate or approximate cost estimate or budget estimate.
- This is usually prepared in initial stages in order to realise approximate cost of the project.
- With the completion of this estimate, the sanctioning authority can fix the financial position & policy required for administration.
- Preliminary estimate charts are prepared regarding the price of identical type of projects.
- During this estimate, the approximate prices of every important objects required for work is displayed discretely in order to realise the requirement & workability of each item of work like the land costs, road costs, electricity & water supply costs, building costs, etc.
- Then the investment in the project must be justified. About 5% is 10% is added as contingencies.
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2. Plinth Area Cost Estimate
- Plinth area = plinth area of building x plinth area price. e.g., if a plinth area estimate of 100 m2 is required in a very specific locality & plinth area price of a building in same locality = 2000/m2.
- Therefore, plinth area estimate = 100 X 2000 = 200000.
- The plinth area is actually computed as, the covered area by considering external dimensions of the building at the ground level without the addition of a Courtyard and other open areas.
- In the case of a multi-storied building, the plinth area estimate is made ready distinctly for every floor level.
3. Cube Rate Cost Estimate
- Cube rate cost = plinth area x the height of building. It is generally utilized in case of multi storied buildings.
- This method of estimation is more precise.
- The price per m3 is assumed on the basis of prices of identical style of buildings located nearby.
- The length & breadth should be assumed from ground level to loft of the roof.
4. Approximate Quantity Method Cost Estimate
- In this method, first entire wall length of the structure is measured
- This length is multiplied by the price per running meter.
- Distinct evaluation is done for the foundation & superstructure.
- In case of foundation, rate per running meter is assumed by considering quantities such as excavation cost, brick job cost up to plinth.
- While, on the contrary, just in case of superstructure quantities like brickwork for wall, wood jobs, floor finishing & so on are taken into consideration for deciding rate per running meter.
5. Detailed Cost Estimate
- This chart is made ready when administrative authority sanctioned the preliminary estimates.
- This is more precise form of estimate.
- Amounts of objects of job are measured & hence the price of each item required for work is computed distinctly.
- The prices of several objects are supplied as per the current workable rates & aggregate estimated cost is evaluated.
- 3 to 5 % of cost for contingencies are included.
- The detailed Estimate is given below subsequently:-
- General Specifications
- Detailed Specifications & Calculation of Quantities
- Drawings/Plans – Layout Plans, Elevation, Sectional Views, Detailed Drawings & so on.
- Designs & Calculations – Required for Buildings, Design of Foundations, Beams, Slab & so on.
- Schedule of Rates & Abstract of Estimated Cost
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6. Revised Cost Estimate
This is a detailed estimate & is required to be prepared under any subsequent circumstances:-
- If the initial sanctioned estimate surpasses over 5%.
- If the expenditure surpasses the quantity of administrative sanction over 10%.
- If there is a material deviation from the first proposal while the price could also be met from the permitted amount.
- The rise is because of sudden surge in materials cost, transportation cost & so on.
7. Supplementary Cost Estimate
- This is actually a detailed estimate & is made ready when additional jobs are required to supplement the first jobs, or when further development is required.
- This is often a new detailed estimate of extra works required along with the original estimate.
8. Annual Repair Cost Estimate
- This is a detailed estimate & is made ready to keep up the structure or job in proper order & secured condition.
- Whitewashing, painting, minor repairs, etc. are assumed while preparing annual repair estimate required for a building.
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Advantage of Estimate
- When this practice continues, estimates (i.e. schedule, timeline, etc.) become more practical since vital problems are discovered soon.
- It can manage the (almost inevitable) improvements that are typically required for the development of software.
- Engineers may begin to work sooner on a project by themselves.
- It aids an organization to seek out the maximum productive method of capital application.
- Engineers fix the rules for effective utilization.
- Operation monitoring is performed by matching real findings with anticipated outcomes.
- Much more reliable predictions aids to effortless project execution.
- Converting more bids.
- Projects are completed quickly & at a cheap price.
- Effortless & quick process.
- Customer partnerships attain a strength of loyalty & continuity as Engineers execute quality projects more efficiently & at diminished costs.
- Working collaboratively is possible.
Disadvantage of Estimate
- This is actually not an efficient operation.
- Significant variation from the specific value is observed.
- This is not developed on drawings or specifications.
- This is an extremely customizable re-usability constraints.
- Interpreted inconsistently with each order.
- There is always a chance of exceeding the budget or schedule.
- It is a cost effective process since it requires professionals.
- It is inefficient for specific kinds of overhead costs which are required to be managed.
- In non-manufacturing processes, it is strenuous to apply it as the link between cost & production cannot be computed.
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Method of Building Estimates
The length, breadth, & height or depth are to be computed from the drawing – plan, elevation, & section. From the study of the drawing, the building is to be pictured within mind & hence the dimensions are to be taken out correctly. The 2 methods of estimation are given subsequently:-
1. Separate or Individual Wall Method –
- Finding out the external length of walls running within the longitudinal direction generally the long walls, out to out, & also the internal lengths of walls running within the transverse direction to in.
- For long wall – for lengthy walls raise the middle length one breadth of wall, which supplies the length of the wall out to out multiply this length by the breadth & the height to get the quantities.
- Long-Wall Length (out to out) = Centre to Centre Length + 1/2 Breadth on one side + 1/2 Breadth on other side = Centre to Centre Length + Breadth
- For short walls – for brief walls subtract from the middle length one breadth of the wall which supplies the length in to in and repeat the process for lengthy walls, subtracting one breadth rather than adding.
- Short-Wall Length (in to in) = Centre to Centre Length – Breadth
2. Centreline Method –
- Sum total length of centre lines of walls, long and short required to be found out.
- Find the entire length of centre lines of walls, of the identical type, long & short having the identical sort of foundation & footing & then find the quantities by multiplying the whole centre length by the respective breadth & the height.
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