Different
types of estimate
1.
Preliminary or approximate estimate or
abstract estimate – is required for preliminary studies of various aspects of a
work or project, to decide the financial position and policy for administrative
sanction by the competent administrative authority. In case of commercial
projects as irrigation projects, residential building project and similar
projects which earn revenue income, the probable income may be worked out, and
from the preliminary estimate the
approximate cost may be known and then it may be seen whether the investment,
on the project is justified or not.
For non commercial
projects or for projects giving no direct return, their necessary utility,
availability of money etc, may be considered before final decision is taken.
The approximate estimate is
prepared from the practical knowledge and cost of similar works. This estimate
is prepared showing separately the approximate cost of all important items of
work as cost of land, cost of each building, cost of roads, water supply,
sanitary works, etc.
2.
Plinth area estimate for building –
prepared on the basis of plinth area of building, the rate being deducted from
the cost of similar building having similar specifications, heights and
construction in the locality.
The plinth area should be
calculated for the covered area by taking external dimension of the floor
level. Courtyard and other open area should not be included in the plinth area.
Plinth area estimate is only approximate and is a preliminary estimate, to know
the approximate cost beforehand.
3.
Cube rate estimate for building - is a
preliminary or an approximate estimate and prepared on the basis of the basis
of cubical contents of the building, the cube rate being deducted from the cost
of the similar building having similar specifications and construction in the
locality.
Cube rate estimate is most
accurate as compared to the plinth area estimate as the height of the building
is also compared.
4.
Approximate quantity method - in this
method, approximate total length of walls is found in running meter and this
total length multiplied by the rate per running meter of wall gives a fairly
accurate work. For this method, structure may be divided into two parts; i)
foundation including plinth and ii) superstructure.
5.
Detailed or item rate estimate – is an
accurate estimate and costs of working out the quantities of each item of
works, and working the cost. Detailed estimate is prepared for technical
sanction of the competent authority, for arranging, contract and for the
execution of work.
If in the abstracts of estimate form the
columns of rates and amounts are left blank (to be filled by contractor) it is
then known as bill of quantity. For detailed estimate, report, Specifications,
drawing, design charts, rates, updated mode of measurement, standard circulars
for taxes and insurances etc are required.
6.
Revised estimate – is a detailed estimate
and is required to be prepared under any one of the following conditions.
a.
When the original sanctioned estimate is
exceeded or likely to exceed by more than 5%.
b.
When the expenditure on a work exceeds or
likely to exceed the amount of administrate sanctioned amount.
c.
When there are materials deviations from
the original proposal, even though the cost may be met from sanctioned amount.
d.
When the expenditure on a work exceeds or
likely to exceed the amount of administrative sanction by more than10%.
7.
Supplementary estimate – is a detailed
estimate and is prepared when additional works required supplementing the
original works, or when further development is regularly during the progress of
work. This is a fresh detailed estimate of the additional works in addition to
the original estimate.
8.
Supplementary and Revised estimate – when
a work is partially abandoned and the estimated cost of the remaining work is
less than 95% of the original work, i.e. less than 95% of the original
sanctioned estimate or when there are material deviations and changes in the
design which may cause substantial saving in the estimate, then the amount of
the original estimate is revised by the competent authority. It is prepared and
fresh technical sanction of the competent authority is obtained.
9.
Annual repair or Maintenance estimate – is
detailed estimate and is prepared to maintain the structure or work in proper
order and safe condition.
10. Extension
and improvement estimate – when some changes and extension are required to be
made in the old work, the cost of which cannot be met out of annual maintenance
estimate, a detailed estimate of the additional work is prepared, called the extension and improvement estimate.
