ESTIMATING AND COSTING

CHAPTER 1
INTRODUCTION TO
ESTIMATION
&
MODE OF
MEASUREMENTS
PREPARED BY: NAMRATA AGNIHOTRI
5/22/2016

Estimate
Estimate for any construction work may be
defined as the process of calculating the quantities
and costs of the various items required in
connection with the work.
It is prepared by calculating the quantities from
the dimension on the drawings for the various
items required to complete the project and
multiplied by unit cost of the item concerned.
5/22/2016 AITS-DS CIVIL DEPT

NEED FOR ESTIMATION
 To ascertain the necessary amount of money
required by the owner to complete the proposed
work.
 Requirements of controlled materials, such as
cement and steel can be estimated for making
applications to the controlling authorities.
 To assess the requirement of tools, plants and
equipment required to complete the work
according to the programme

 To fix up the completion period from the volume
of works involved in the estimation.
 To draw up the construction schedule and
programme and also to arrange the funds
required according to the programming.
 To invite tenders and prepare bills for the
payment.
 An estimate for an existing property is required
for valuation.

DATA REQUIRED FOR
ESTIMATION
 To prepare an estimate, drawing consisting of
the plan ,the elevation and the section through
important points , along with detailed
specification giving specific description of all
workmanship, properties and proportion of
materials are required.

Quality of a good estimator
• In preparing an estimate, the Estimator must have
good knowledge regarding the important rules of
quantity surveying.
• He must thoroughly understand the drawings of
the structure, for which he is going to prepare an
estimate.
• He must also be clearly informed about the
specifications showing nature and classes of works
and the materials to be used because the rates at
which various types of works can be executed
depend upon its specifications.

 A knowledge of the details of construction work.
Experience in construction work.
Having information regarding the materials
required, machinery needed, overhead problems, and
costs of all kinds.
Good judgment with regard to different localities,
different jobs and different workmen.
Selection of a good method for preparing an
estimate.
Ability to be careful, thorough, hard working and
accurate.

Before preparing the estimate, the
estimator should visit the site and make a
study of conditions, there. For example, if
the construction of a large building is
planned, the estimator or his
representative should visit the site and:
 Note the location of the proposed building.
 Get all data available regarding the soil.
 Make a sketch of the site showing all important
details.

 Obtain information concerning light, power,
and water.
 Secure information concerning banking
facilities.
 Note conditions of streets leading to railway
yards and to material dealers, and
 Investigate general efficiency of local
workman.

Types of estimates
Detailed estimate
A preliminary or approximate or rough estimate
A quantity estimate
Revised estimate
A supplementary estimate

 Detailed estimate
 This includes the detailed particulars for the
quantities rates and costs of all the items
involved for satisfactory completion of a project.
Quantities of all items of work are calculated
from their respective dimension on the drawing
on a measurement sheet. Multiplying these
quantities by their respective rates in a separate
sheet the cost of all items of work are worked
out individually and summarized.

All other expenses required for satisfactory
completion of the project are added to the above
cost to frame the total of detailed estimate. This
is the best and most accurate estimate that can be
prepared.
A detailed estimate is accompanied by REPORT,
SPECIFICATION, DETAILED DRAWING
SHOWING PLANS, DIFFERENT SECTION,
KEY PLAN, BASIS OF RATES.

PRILIMINARY
ESTIMATE
This is an approximate estimate to find out an
approximate cost in a short time and thus and
thus enables the authority concerned to consider
the financial aspect the scheme.

A Quantity Estimate
This is a complete estimate or list of quantities for
all items of work required to complete the
concerned project. The quantity of each individual
item of work is worked out from respective
dimensions on drawing of the structure.

Revised Estimate
A revised estimate is a detailed estimate for the
revised quantities and rates of items of works
originally provided in the estimate without
material deviation of structural nature from the
design originally approved for a project.

It is accompanied with a comparative statement
abstract form showing the probable variation for
quantity, rate and amount for each item of work
of the project as compared with the original
estimate side by side stating the reason of
variation.

It is required for the
following reason
When a sanctioned estimate is likely to exceed
by more than 5% either from the rates being
found insufficient.
When the expenditure of work exceed or is likely
to exceed by more than 10% of the
administrative approval
When it is found that the sanctioned estimate is
more than the actual requirement.

A Supplementary
Estimate
While work is in progress some changes or
additional works due to material deviation of
structural nature from the design originally
approved may be thought necessary for the
development of a project. An estimate is then
prepared to include all such work

How to prepare a detailed
estimate
In this method the rates per unit work of one item
including profit are considered first and the total
cost for the item is found by multiplying the cost
per unit of the rate by the number units.
the procedure for the preparation of a
detailed estimate is divided into two parts.
1) detail measurement.
2) abstract of estimated cost

1. Measurement form
The details of measurements of each item of
work are taken out
and quantities of each and every
item is computed in a prescribed
form known as measurement form as under

Item No. Description No. Length Breadth Height Quantity
Measurement Form:

2. Abstract of cost form
The cost under each item of the work is
determined from the quantities and total cost is
worked out in a prescribed form called abstract of
cost form as shown on next slide

Cont.
item no Description quantity unit of payment Rate Amount
Cost Form:

Definitions
Contingencies :
The term “contingencies”
indicates the incidental expenses of a
miscellaneous character which can not be
reasonably predicated during preparation of the
estimate and to meet such unforeseen expenses an
additional amount of 3% to 5% of the estimated
cost of works is provided in the total estimate.

For example, suppose there is an item in an
estimate for cement plastering 1:4 with neat
cement finish but during execution it is desired to
provide nosing at the end of steps. As there is no
allocation of funds for this small work, the cost of
such work may be met up from the contingency
fund.

 Lump-sum item:
This is the item of work which
is very difficult to measure or assess during its
execution and a lump sum rate is provided in the
estimate. The work of site cleaning dewatering
from a small diameter tube well till sand free
water is obtained, removing roots of a tree etc.

 Prime cost:
It is the net cost or the purchase cost
of articles at shop and refers to the supply of the
articles only and not to the carrying out of work.
During preparation of an estimate it is not always
possible to specify the exact type or brands of
materials required as in the case of doors and
window or water supply and sanitary fitting
according to the choice of the owner.

The owner may supply such articles or may
instruct a contractor to purchase such articles for
the work. The fitting and fixing charges are paid
separately. In order to execute such item of work
a reasonable amount is provided in the estimate
as prime cost.

 Day work:
During execution of a project there
may be certain type of work which are not
included in the schedule and can not be paid by
measurement. Those are paid for on the basis of
the actual quantity of materials and labour hours
required to complete the work is called as day
work.

Provisional sum:
It is an amount arbitrarily
provided by an experienced estimator in the total
estimated cost of a project to carry out some
special type of work whose detail can not be
known at the time of estimate such special work
as installation of lifts, shifting of water lines,
sewer lines or cable connection etc. for which full
information may not known at the time of
preparing estimate a reasonable amount is
provided in the estimate as provisional sum.

Provisional quantities:
these are the additional
quantities against schedule items but uncertain in
execution and provided separately in the estimate.
During preparation of an estimate when it is
apprehended that additional quantities against
some item may be required due to variation of site
condition then those quantities are estimated
separately from the dimension of the drawing and
kept separate in the bill of quantities with a
heading provisional quantities.

 Over head charges:
This includes such item as office
rent and depreciation of its equipment , salaries of
staff, lighting, travelling etc. included in the
overhead charge. This is usually 2.5% of the net
cost of a unit of rate and may rise up to 5%

ESTIMATING AND COSTING

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