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Types of Approximate Estimate

Approximate Estimate:

Approximate estimate is also called as preliminary estimate. It is an approximate or rough estimate prepared to obtain the cost of a project in short time, without taking out actual quantities.

 Purpose of Approximate Estimate:

1. For government project approximate estimate is required for              administrative approval.

2. Due to approximate estimate it is easy to check/ study feasibility        of project.

3. Whether the new project is beneficial and to study cost- benefit           ratio approximate estimate is necessary.

4. When one has to fix the rent for the property it is necessary to             know the approximate estimate.

5. This type of estimate is helpful to fix the tax.

6. For existing building if valuation has to be done approximate              estimate plays the important role.

 Types of Approximate Estimate:

1.   Plinth Area Method

2.   Cubical Content Method

3.   Service Unit Method

4.   Typical Bay Method

5.   Approximate Quantity Method 


1) Plinth Area Method:

Ø  This method is also known as square meter method

Ø  In this method, plinth area of proposed building is worked out in m2 from plan of proposed building by multiplying length and breadth (outer dimensions  of building)

Ø  Then approximate cost of proposed building is worked out by multiplying total plinth area calculated in m2 with plinth area rate

Ø  i.e. Approximate Cost of

Proposed Building   = Total Plinth Area of Proposed Building in m2 X  Plinth Area Rate

Ø  Here plinth area rate is obtained from the cost of similar existing building having similar specification, height & construction, in the locality.

i.e. Plinth Area Rate = Cost of Construction of Existing Building/ Plinth Area of Existing Building 

Hence,

Approximate Estimate for

       Proposed Building  = Plinth Area of Proposed Building X Plinth Area Rate of Existing Building

 Eg. For proposed building having plinth area 100 sq.m at 1000 sq.m plinth area rate of existing building, approximate cost of a proposed building works out as 1,00,000/-


 2) Cubical Content Method:

Ø  This method is generally used for multi-storied buildings.

Ø  It is more accurate that the other two methods viz., plinth area method and unit base method.

Ø  The cost of a structure is calculated approximately as the total cubical contents (Volume of buildings) multiplied by Local Cubic Rate.

Ø  The volume of building is obtained by Length x breadth x depth or height. The length and breadth are measured out to out of walls excluding the plinth off set.

Ø  The cost of string course, cornice, corbelling etc., is neglected.

Ø  The cost of building = volume of building x Rate per unit volume.

Eg. For proposed building of cubic content of 500 m3 at 200 per m3 works out as 1,00,000/-


 3) Service Unit Method:


Sr. No.

Building

Service Unit

01

School

Class Room

02

Hospital

Bed

03

Theatre

Seat

04

Bridge

Meter of Span

05

Stadium

Seat

06

Hostel

Student

07

Water Tank

Litre

Ø    In service unit method no. of service unit is decided for calculating approximate estimate, such as per kilometer for a highway, per meter of a span for a bridge, per classroom for school building, per bed for hospital, per liter for water tanks, per seat for cinema hall etc.

Ø    These units are considering first then approximate cost is calculated by multiplying the cost per service unit by the no. of service unit in the structure.

Ø    Approximate estimate = No. of service unit x Cost per service unit

 

 4) Typical Bay Method:

Ø  This method is used for the buildings have similar column spans

Ø  Over a larger area such as factory buildings, go-downs, railway platform.

Ø  Cost of each bay is found out by using other method of estimation. Then the cost of whole factory building is worked out by multiplying the total number of bays by the cost of construction for each bay.

Ø  Approximate cost = No. of bays x Cost of one bay

 

 5) Approximate Quantity Method:

Ø  In this method, various quantities are worked out with the help of many short-cuts. For instance, the wall foundations are measured in linear measurements i.e., in running meters.

Ø  The approximate quantities of items such as excavation, foundation concrete, brickwork up to plinth level and damp-proof course are computed per running length and with the help of rates of these items, a fairly accurate rate per running meter.

Ø  This rate when multiplied by the total running measurement gives the approximate cost of the building up to plinth level.

Ø   Similarly, the superstructure is measured in running measurements and a suitable rate per running meter is built-up including brickwork, inside and outside finishing, woodwork, etc.

 

 

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