Quantity
Survey
Modern quantity surveyors
provide services that cover all aspects of procurement, contractual and project
cost management. They can either work as consultants or they can be employed by
a contractor or sub-contractor.
The main role of Quantity
Surveyors is to estimate the building cost. Each building can be divided into
different parts, cost of each part can be estimated and by adding cost of all
parts of building together will
give contractors an estimated cost for the whole work. It's been proved in
practice that by adding cost of quantities, material used for project and
labour will provide us with the total cost of the project. We must not forget that
the bill provided by quantity surveyor is an estimate and it is prepared before
any work starts to give a contractor estimated cost. Contractor then agrees to
do the work based on the estimated cost that represents the proposed work.
Position of Quantity
surveyor came available after builders realized how much work it requires to do
all the measurements and calculations and it would be much more cost effective
for them all to employ one person to do it. As soon as they implement this in
practice architects and employers soon realized the effectiveness of quantity
surveyors.
As we've already learned
above the estimated cost of construction work prepared by quantity surveyor is
used for tendering. Each builder can therefore price the work that needs to be
done based on same bill of quantities and this is what gives building industry
a healthy competition.
Every good quantity
surveyor must have a good knowledge of building materials and construction.
Surveyor must be very systematic and careful to provide correct calculations as
well as be able to visualize drawings and details. To make sure that the
quantity bill is accurate, surveyor needs to be sure of all requirements of
architects. Arranged bill needs to be clear and easily understood to prevent
any costly misunderstandings.
There is basically two method's
1) Rough cost estimate
2) Detailed cost estimate
Requirements for Estimation:-
1) Drawings, i.e Plans, elevation, sections etc.
2) Specifications.
3) Rates.
1) Rough Cost estimate :-
A Rough cost estimate is the approximation of the cost of a program, project, or operation. The Rough cost estimate is the product of the cost estimating process. The Rough cost estimate has a single total value and may have identifiable component values.
2) Detailed cost Estimate:-
The preparation of detailed estimate consists of working out quantities of various items of work and then determines the cost of each item. This is prepared in two stages.
I) DETAILS OF MEASUREMENTS AND
CALCULATION OF QUANTITIES.
The complete work is divided into various items of work such as earth work concreting, brick work, R.C.C. Plastering etc., The details of measurements are taken from drawings and entered in respective columns of prescribed preformed. The quantities are calculated by multiplying the values that are in numbers column to Depth column as shown below:
Details of measurements form
In detailed estimate :-
1) Long and Short Wall Method
2) Centre Line
Method
3) Partly centre line & partly
cross wall method.
4) Graphical Method
1). Long & Short Wall Method:-
In this method, the wall along the length
of room is considered to be long wall while the wall perpendicular to long wall
is said to be short wall. To get the length of long wall or short wall, calculate
first the centre line lengths of individual walls. Then the length of long
wall, (out to out) may be calculated after adding half breadth at each end to
its centre line length. Thus the length of short wall Measured into in and may
be found by deducting half breadth from its centre line
length at
each end. The length of long wall usually decreases from earth work to
brick work
in super structure while the short wall increases. These lengths are
multiplied by
breadth and depth to get
quantities.
2) Centre Line Method:-
This method is suitable for walls of
similar cross sections. Here the total centre line
length is multiplied by breadth and depth of respective item to get the
total quantity
at a time. When cross walls or partitions or verandah walls join
with main
all, the centre line length gets reduced by half of breadth for each
junction.
Such junction or joints are studied carefully while calculating total centre
line length.
The estimates prepared by this method are most accurate and quick.
3) Partly centre line & partly cross wall method:-
This
method is adopted when external (i.e., around the building) wall iSOFT
one
thickness and the internal walls having different thicknesses. In such cases,
centre line
method is applied to external walls and long wall-short wall method issued
to
internal walls. This method suits for different thicknesses walls and different
level of
foundations. Because of this reason, all Engineering departments are
practicing this
method.
4) Graphical Method:-
Graphical method is mostly use for
Cutting and Filling in Road and Cannel project’s.
In
this method we use Grap
paper for finding cutting and filling.
Thanks!
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