The action or profession of a person who estimates the cost of the materials and labour necessary for a construction job
The estimation and costing of any structure is defined as the process of determination of quantities of items of work, and its cost for completion.
Purpose of estimation
1.From the estimate of a work it is possible to determine what materials and in what quantities will be required for the work so that the arrangements to procure them can be made.
2.The number and kind of workers of different categories who will have to be employed to complete the work in the specified time can be found out from the estimate.
3.An estimate will help in determining amount and kind of equipment needed to complete the work.
4.The estimate of a work and the past experience enable one to estimate quite closely the length of time required to complete an item of work or the work as a whole.
Types of estimates
1. Approximate or Preliminary Estimate
The estimate which prepared using any rough method to get the approximate cost construction anticipated in a project is called an approximate or rough estimate. Since this estimate is normally prepared in the preliminary estimate.
2. Plinth Area Estimate
It is defined area of a building measured at floor level. It is measured by taking external dimensions excluding plinth offset if any. 28.What are the methods of taking out estimates
3. Cubical Content Estimate
The cube method estimating is a single rate method of estimating based on the cubic content of a building. Cost per cubic metre method is specific for building projects and aims to overcome the current criticism floor area method that does not take into account possible variations of the storey height.
4. Detailed Estimate
The estimate, which provides the itemwise quantities of works, item wise unit rates and itemwise expenditure anticipated in thre project/construction, is called a detailed estimate .
A detailed estimate is accompanied by
Detailed drawings showing plans, different sections, Key or Index plan etc.
Design data and calculations
The basis of rates adopted in the estimate.
5. Revised Estimate
The estimate, which is prepared
• When any major change or alteration is made in the plan / structural arrangement, with or without affecting the estimate cost, and
When the estimated cost is likely to exceed by more than 5% during execution, due to increase in the cost of materials and labour or due to increase in the cost of materials and labour or due to alterations in the items of works to get the revised quantities /rates/ amount is called a revised estimate .
6. Supplementary Estimate
This is required due to supplementary works which are fairly independent of the work at first sanctioned. So, supplementary estimate is due to material deviation of a structural nature from the design originally approved.
No comparative abstract form is required. This is an estimate for additional works only. The abstract shows the original estimate and total amount of the sanction required including supplementary amount
Supplementary estimate is required due to some new works or due to change of design, so additions or revisions of drawings may be necessary.
7. Annual Repair of Annual Maintenance Estimate
In order to keep building and roads in perfect condition, annual repairs should be carried out as follow:-
In case of a building-white washing, oiling and painting of doors and windows, cement plaster repairs (inside & outside), repairs of floors etc. In no case this annual repair amount should increase more that 11/2% to 2% of the capital cost of the building.In case of a road-filling patches, maintenance of berms etc.