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Introduction to Quantity
Surveying
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QUANTITY SURVEY???
Introduction
 Once a construction project is completed or depending on the form of
contract upon completion of certain parts of the work, the contractor must
be paid for appropriately completed works.
 This would then require that the actual works done be somehow
estimated or measured for payment purposes.
 On the other hand to estimate how much a civil engineering project may
cost, the actual quantities of materials, labor, equipment etc. that is needed
for the construction work must be calculated at the beginning of the
work.
 Such work of calculating the amount of materials and other
incidentals necessary for the realization of the work is called quantity
surveying.
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QUANTITY SURVEY???
Introduction Cont.
 Quantity surveying is a term or processes used in the construction
industry to take measurements of civil works, prepare
specifications, and estimate the cost of works either for each trade of
work or for the whole project.
 The term “surveying” means to inspect, study, review, investigate,
asses, and hence “to measure” therefore the term “quantity
surveying” means “quantity measuring” as applied to civil
engineering projects.
 Quantity surveying is the application of standard methods of
measurement to quantify the amount of various items in a
construction project, for the undertaking of valuation, and certifying
payments.
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QUANTITY SURVEY???
Introduction Cont.
 The following tasks are covered in quantity surveying.
1. Preparation of Specification
2. Taking measurements of civil works (Taking off quantities and
preparing BOQ)
3. Preparation of approximate (preliminary) cost estimate at the
very early stage of the project
4. Preparation of detail cost estimate at different stages (taking as
built measurements and preparing payment certificates or
approval of payment certificates prepared by taking
measurements)
5. Valuation of property
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QUANTITY SURVEY???
Pur pose of Quantity Sur veying
 The purpose of quantity surveying hence the preparation of Bill of
quantities is:
i. Assist the client to have an accurate estimate of the volume of
work as well as the required budget.
ii. To assist in the accurate preparation of tenders, by providing
uniform measurement of quantities.
iii. To give an accurate checklist of work accomplished
iv. To assist in the certification of payments
v. To give insight into the required variation work amounts.
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ESTIMATE???
a. to judge tentatively or approximately the value, worth,
or significance of
b. to determine roughly the size, extent, or nature of
c. to produce a statement of the approximate cost of
Merriam - Webster
“It is a valuation based on opinion or roughly made from imperfect
or incomplete data, a calculation not professedly exact, an
appraisement; also a statement, as by a builder, in regard to the
cost of certain work.”
Max B. Fajardo
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“Estimating is the most important of the practical aspects of
construction management and the subject deserve a closest
attention of one aspiring to a career in the profession. It is
comparatively simple subject to understand, however, as it
bring one up against practical work, methods and
procedure, knowledge of it cannot be acquired without close
application.”
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Purpose of Estimating
To give a reasonably accurate idea of the cost
An estimate is necessary to give the owner a reasonably accurate idea of the cost to
help him decide whether the work can be undertaken as proposed or needs to be
curtailed or abandoned, depending upon the availability of funds and prospective
direct and indirect benefits. For government works proper sanction has to be
obtained for allocating the required amount. Works are often let out on a lump sum
basis, in which case the Estimator must be in a position to know exactly how much
expenditure
he
is
going
to
incur
on
them
1. Estimating Materials
2. Estimating Labor
3. Estimating Equipment
4. Estimating Time
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Types of Construction Estimates
1. Estimates for Conceptual Planning
Based on very general parameters of facility size,
anticipated quality of construction and use of facility.
Conceptual Estimate – is prepared based from only a
conceptual description of the project.
-Is done before plans, specifications and other
project details have been developed.
- ±15 – 20 % accurate
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Types of Construction Estimates
2. Estimates for Feasibility
Using preliminary design information and after project
scope is completely defined.
An estimate of project cost that is prepared before
complete construction documents are available.
±15 – 20 % accurate
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Types of Construction Estimates
3. Estimate During Engineering and Design
Based on schematic level design documents, it is probable
that major quantities can be quantified, concrete, steel based
from type of construction.
The designer and owner may use the estimate to evaluate
expected total project cost but for the purpose of reviewing
design cost drivers and performing value engineering
Value Engineering – a evaluation of a project objective
function for the purpose of bettering the objectives in terms
of cost and functional parameters
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Types of Construction Estimates
4. Estimates for Construction
Itemized cost computation based on complete set of contract documents
(incl. plans and specifications)
Bid estimate submitted to the owner either for competitive bidding or
negotiation consists of direct construction cost including field supervision,
plus a mark-up to cover general overhead and profits. The direct cost of
construction for bid estimates is usually derived from a combination of the
following approaches.
•Subcontractor quotations
•Quantity takeoffs
•Construction procedures.
5% accuracy
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Types of Construction Estimates
5.Control Estimates.
For monitoring the project during construction, a control estimate is
derived from available information to establish:
Budget estimate for financing
Budgeted cost after contracting but prior to construction
Estimated cost to completion during the progress of construction.
6.Estimate for Change Order
Performed on the project site in response to an owner – directed
change in the project.
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Estimating Techniques
Approximate Estimates
An approximate estimate is an approximate or rough estimate prepared
to obtain an approximate cost in a short time. For certain purposes the
use of such methods is justified.
Detailed Estimate
A detailed estimate of the cost of a project is prepared by determining the
quantities and costs of every thing that a contractor is required to provide
and do for the satisfactory completion of the work. It is the best and most
reliable form of estimate. A detailed estimate may be prepared in the
following two ways
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Qualification of an Quantity Surveyor
1. A thorough understanding of architectural drawings.
2. A sound knowledge of building materials, construction
methods and customs prevailing in the trade.
3. A fund of information collected or gained through experience in
construction work, relating to materials required, hourly output
of workers and equipment, overhead expenses and costs of all
kinds.
4. An understanding of a good method of preparing an estimate.
5. A systematic and orderly mind.
6. Ability to do careful and accurate calculations.
7. Ability to collect, classify and evaluate data that would be
useful in estimating.
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Data Required for Preparing an Estimate
1. Plans, sections and other
relevant details of the
work.
2. Specifications indicating
the exact nature and class
of materials to be used.
3. The rates at which the
different items of work are
carried out.
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Steps in Preparing Estimates
1 . Taking out quantities
- Measurements are taken off from the drawings and entered on measurement
sheet or dimension paper. The measurements to be taken out would depend upon
the unit of measurement.
2. Squaring out
- Working out volumes, areas, etc. and casting up their total in recognized units.
3. Abstracting
- In the third step all the items along with the net results obtained in the second
step are transferred from measurement sheets to specially ruled sheets having
rate column ready for pricing.
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Work Breakdown Structure
Work Breakdown Structure (WBS)– provide a common
hierarchical framework for summarizing information and for the
quantitative reporting to customers (client/owner) and management.
Purpose of Work Breakdown Structure
1.Provide an organized manner of collecting project cost data in
a standard format for estimating, cost reporting and cost tracking
2. Provide a checklist for categorizing cost
3.Provide a means to maintain historical cost data in a standard
format.
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Basics for Preparation of Estimates
Review Contract Documents
Thoroughly examine the constructions documents
Drawings and Specifications
General Conditions – part of the contract documents that defines the
rights, responsibilities and relationships of all parties to the construction
contract.
It is appropriate to make notes of anything that can affect construction
duration and the cost to perform the work or add indirect and overhead cost to
the work
Prebid Conference – a meeting held prior to bid opening for the purpose of
explaining the project and answering questions that bidders have with respect to
the contract documents and the work.
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Basics for Preparation of Estimates
Planning The Work
Thoroughly understand the scope of work and the project environment.
A detailed review enables the estimator to formulate a construction sequence
and duration.
A site visit is strongly recommended to enable the estimator to relate the
physical site characteristics to the available design parameters and details.
Quantities
Quantity Take-off – must be as accurate as possible and should be based on all
available engineering and design data.
Quantities should be shown in standard units of measure and should be
consistent with the design units.
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Basics for Preparation of Estimates
Types of Cost
Direct Cost – all cost elements that can be associated with a specific item of
project work e.g. cost of labor, cost of materials, cost of equipment
Indirect Cost – cost that cannot be attributed to a single task of construction
work e.g. overhead, profit, and bonds.
Profit – amount of money, if any that a contractor retains after completing a
project and paying all cost for materials, labor and overhead.
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Basics for Preparation of Estimates
Productivity and Price Resources
Historical production and cost data from similar past work are excellent
resources of when adequate details have been saved and adjustments to
project specifics can be defined.
Development of Specific Task
Developed task descriptions must describe the scope and material
requirement.
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Basics for Preparation of Estimates
Unit Cost
Labor Unit Cost – cost based on a defined crew that performs the task
at an assigned production rate.
Equipment Unit Cost
Material Unit Cost – developed using vendor quotes , historical cost
commercial pricing sources and component calculations.
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Basics for Preparation of Estimates
Cost and Pricing
cost for each task is developed by summing up the direct cost elements
for labor, equipment, materials, supplies and subcontractors.
Indirect cost and other markups associated with each task or work item
should be identified and considered properly.
When using historical pricing, adjustment must be made for location,
work methodology, quantity of work, and other dissimilarities that affect
prices.
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Basics for Preparation of Estimates
Supporting Documents
Should always remain mindful of the documentation necessary to
support the estimates.
Narratives of Contract Cost – contains discussion, considerations
and the developed construction plan.
Project Narrative
Construction Schedule
Equipment and Material Utilization
Labor Discussion and Utilization
 Estimate Backup Data – backup documentation
Quotations
Drawing and Sketches
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Reference:
Introduction to Estimates by Engr. Cyrus D. Esguerra
http://pmbook.ce.cmu.edu/05_Cost_Estimation.html
http://www.misronet.com/estimating.htm
Construction Management Fundamentals by Knutson, Schenayder,
Fiori, Mayo
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