## What is Estimate in Building Construction

Construction estimate in building construction are used for the estimations of costs of a construction project so that contractors can execute the projects with smart planning of each and every activity. With the help of construction estimates contractors can make a plan of each and every activity, can predict the overall costing of the project by accurately preparing the cost estimates everything involved in the project. One more thing which helps the contractors is that estimates helps the contractors in predicting their profit margins even before the starting of the project so that they can decide whether or not they should opt for the project.

These are the 6 smart ways of preparing estimate for building construction which are used by contractors to predict construction costs.

**1) Plinth Area Estimate Method**

The plinth area estimate is prepared by considering the cost per plinth area of a similar type of construction in the locality. Plinth area cost estimate is prepared on the basis of plinth area of building which is the area covered by external dimensions of building at the floor level and plinth area rate of building which is the cost of similar building with specifications in that locality. Open areas, courtyards, etc. are not included in the plinth area. If the building is multi-storied, the plinth area estimate is prepared separately for each floor level.

For example, if the plinth area of the proposed building is about 100 sq.m in a particular locality and the plinth area rate of a building in the same locality is 2000 per sq.m then,

The cost of the building by plinth area estimate is 100 X 2000 = 200000.

**2) Cube Rate Cost Method**

The cube rate cost estimate method is more accurate than the plinth area estimate. The cubical rate of construction is obtained by dividing the total construction cost by its cubical content. Cube rate cost estimate of a building is obtained by multiplying plinth area with the height of building.

Height of the building should be considered from floor level to the top of the roof level. It is more suitable for multi storied buildings. Suppose, the cubic rate in an area is Rs. 5000 / m3 and the area of the proposed construction is 1000m3.

Approximate cost of construction = 5000 x 1000 = Rs. 50, 00,000.

**3) Service Unit Method**

In the Service Unit Method, the Service Unit indicates the most important unit in a structure. The entire structure is divided into a number of service units. For example, in a school building, the service unit is in the classroom. Then, the approximate cost of structure = Number of service units in the structure x cost of service units in a similar existing structure.

The approximate estimate of the school building is prepared on the basis of the service unit and the service unit for the school building is the classroom.

**4) Floor Area Method**

The floor area is calculated by deducting the area of the wall from the plinth area.

Floor area = Plinth area – Area of wall

In the calculation of the area of walls, the thickness of the wall shall be inclusive of finishes and dado if the height of such finish is more than 1 m from floor finish.

i) Door area another opening in the wall.

ii) Built-in cupboard, almirah, etc. appearing within a height of 2.2 m from the floor.

iii) Flues that are within the wall.

In the calculation of the area of walls, the thickness of the wall shall be inclusive of finishes and dado if the height of such finish is more than 1 m from floor finish.

**5) Carpet Area Method**

Carpet area means the floor area of an apartment, excluding the area covered by the external walls, areas under services shafts, exclusive balcony and exclusive terrace area. Still, it includes the area surrounded by the internal partition walls of the apartment.

The carpet area is the floor area less the area of the followings portions (as per IS 3861)

1) Verandah

2) Corridor, Passage

3) Entrance hall and Porch

4) Staircase

5) Bathroom and W.C.

6) Kitchen and Pantry

7) Store, Machine Room for lift

8) Shaft for sanitary pipes etc.

Estimated Cost = Plinth area x plinth area rate

**6) Typical Bay Method**

This method is useful in the case of a building that has several similar bays. A bay is a space from the center to the center of two successive columns. A typical interior bay is selected and its total cost is worked out. Then,

Approximate cost of proposed building = numbers of bays x cost of one bay

**Conclusion**

These are the methods that are used for the preparation of estimates in building construction, Accurate estimates are the keys for winning a tender but one thing a person should always remember while preparing estimates is that the accuracy of costs is the most crucial part of the process. A contractor should always rec-check his/her calculations twice in the estimates. Read and learn **tips about the accurate cost estimation process** on the internet and books to master it.