Approximate Estimate is
made to find out an approximate cost in a short time and thus
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Approximate estimate is prepared with preliminary investigation and survey. It does not require detailed surveying design, drawing etc. It is basically done to evaluate feasibility of a project. If it is observed from approximate estimate that the cost of the project is very high then the project may be abandoned without preparing a detailed estimate. Thus the cost required for detailed surveying design or drawing required for preparation of detailed estimate is saved.
Purpose of Approximate Estimate
1. Approximate estimate provides an idea about the cost of the project, which enables the authority to check the feasibility of the projects considering the funds available for the project.
2. Approximate estimate does not require any detail investigation, design or drawing
and hence saves
both time and money.
3. If
several alternatives are available for the original works, a comparison is done from approximate
estimate and the decision is made to select the project according to this comparison.
4. Approximate
estimate is required for getting the administrative approval for conducting detailed
investigation, design and estimation.
5. Approximate
estimate for a property or project is required for insurances and tax scheduling.
Methods Of Approximate Estimate
There are
seven methods used for approximate estimate of the building
· Plinth
area or square meter method
· Cubic
rate or cubic-meter method
· Approximate
quantities with bill
· Service
unit or Unit rate method
· Bay
Method
· Cost
comparison method
· Cost
from materials and labor
a) Plinth area or square meter method :- This is prepared on
the basis of plinth area of the building. The rate for unit plinth area is deducted from the
cost of a building having similar specifications and dimensions in the locality. The
plinth area is calculated for the covered area by taking external dimensions of the
building at the floor level. Plinth area does not include the courtyard or any
other open spaces.
b) Cubic rate or cubic-meter method :- In this method the
cost is estimated by multiplying the cubical contents of the building (length × breadth ×
height) with the rate calculated in cubic meter which is deducted from a building having
similar specifications and dimensions in the locality.
c) Approximate quantities with bill :- In this method the
total length of walls is calculated from the plant. Length of different sections of the
wall like foundation including plinth and super structure and area of wood work, flooring and
roofing is calculated separately. These items are then multiplied by
their cost per
running meter length or area in sq. to obtain the total cost.
d) Service unit or Unit rate method :- In this method all
costs of a unit quantity such as per km. (highway), per meter (bridge), per classroom (may
be school or colleges), per bed (hospitals), per cubic meter (water tank) is
calculated and multiplied with the cost per unit deducted from similar
structures in the locality.
e) Bay Method :- The
rate for one additional bay is calculated. Then the approximate estimated cost
for the building is worked
out by multiplying the number of bays in the proposed building with the
cost of one such bay.
f) Cost comparison method :- When a number of
dwellings of similar specification and dimensions are constructed as a part
of a larger project for example staff quarters, the approximate estimates for
all such dwellings can be
estimated by multiplying the quantities of various items for a prototype
structure with
present market rates.
g) Cost from materials and labor :- Here approximate
quantities of materials and labor per sq. of plinth area are calculated with some
empirical equations or from past experience. This is then multiplied by total plinth
area of the building to calculate the total quantity of materials and labor
required Estimation and Professional Practices.
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