Lec - 2.ppt ganbella university quantity estimta

Chapter II: Specification
Contract, Specification and
Quantity Surveying (CEng5101)

Specifications
Defn: Specification is a statement giving
 clear and concise description of the work
required,
 quality of materials and workmanship to be
employed in the execution of any project and
 the methods of work execution and testing to be
adopted to ensure compliance, precautions etc,
required.
 Instrument to understand the nature of the work
and what the work shall be 2

Cont’d…
 The specifications should clearly specify: -
 1) Design and drawing
 2) Labor employment
 3) Materials to be used
 4) Construction method
 5) Equipments used
3

Cont’d…
 The information that is needed for
construction is usually conveyed by two basic
communication lines. They are:
 Drawings (pictorial) and
 Specifications (written).
4

Cont’d…
 The drawings should generally show the
following:
1) Dimensions, extents, size, shape, and location of
component parts.
2) Location of materials, machineries, and fixtures
3) Interaction of furniture, equipments and space
4) Schedules of finishes, windows and doors
5

Cont’d…
 Specifications generally describe the following: -
1. Type and quality of materials, equipments, labor or
workmanship
2. Methods of fabrication, installation and erection
3. Standards, codes and tests
4. Allowance, submittals and substitutions
5. Cost included, insurance and bonds
6. Project records and site facilities.
6

CEng 511, Specifications 7
Comparison of Drawing and specifications
Show the arrangement of
the rooms and various parts,
and the dimensions-length,
breadth, and height, with
very brief descriptions of
different parts.
Combinations of drawings and specifications define completely the structure.
Furnish the details of
different items of work, the
quality of materials,
proportion of mortar and
workmanship which are
required to execute tasks.
Specification Drawing of Building

8
Purposes of specification
 It serves as a contract agreement document between
the owner and contractor.
 It serves as a guide to bidders at the time of tendering
 It is helpful for the guidance of supervision
 Guide the contractor for the purchase of materials.
 It serves as a guide to the manufacturing agencies.
 Serve as a part of contract document to limit and
describe the rights and obligations of each contracting
parties.

Cont’d..
 Guide the contractor for the purchase and/or hiring
of equipments.
 Serve as fabrication and installation guide for
temporary and permanent works.
 Serve for the owner to know what he/she is entitled
to receive
 During day to day execution of the works,
specifications will be used to administer the
contract, supervise the works and certify payment
certificates and finally handing over the project. 9

Broad classification of specifications
 Specifications can be broadly classified into
four categories as follows:
1. Manufacturer’s specification:
Manufacturers prepare specification of their
product for the guidance of their users,
which may include property description and
installation guide lines.
10

Cont’d..
2. Guide Specification :
 Specifications prepared by an individual or
group of individuals based on manufacturer’s
specifications, established trends of
workmanship, service and laboratory tests
and research findings to be used as guide
lines for preparation of contract
specifications.
11

Cont’d..
3. Standard Specification:
 Specifications which are intended to be used
as a reference standard in the construction
of a project. The guide specification which
has been standardized by a recognized
authority is considered as standard
specification.
12

Cont’d..
4. Contract (Project) Specification:
 the specification prepared for a
particular project to accompany the
drawings and other contract
documents.
13

Cont’d..
 The specifications described above can be
prepared following the format which has
general and specific parts:
1) general specification and
2) specific specification).
14

15
Cont’d…
A. General Specification
 It is a short description of different parts of
the work specifying materials, proportions,
qualities, etc.
 Specifies the nature and class of the work
and materials in general terms.
 Gives general idea of the whole work and
is useful for preparing estimates.

……..Contd
Examples of General Specification
 20 cm thick HCB wall both sides left for plastering.
Price shall include cement mortar 1:3 bed,
 2mm thick best quality PVC floor tiles stuck to floor
with approved type adhesive. Price includes adhesive.
 Reinforced concrete quality C-25, 360kg of cement/m3,
filled in to formwork and vibrated around rod
reinforcement. (formwork and reinforcement measured
separately)

…. contd
B. Particular/Detailed Specification
 Specifies the qualities and quantities of materials,
the proportion of mortar, workmanship, the method
of preparation and execution and the methods of
measurement.
 Describes what the works should be and how they
shall be executed and constructed

18
Examples: Detailed Specifications
 Material Specification (grades of material: C-
25, S-400, mild, pre-stressing tendon, marble
from Wollega, ordinary Portland cement form
Muger etc.
 Workmanship Specification (quality of
workmanship: for instance, in steel works
qualified welder)
 Performance specification
 Manufacturers Specification

technical specifications.
 There are the following types of technical
specifications.
1. Proprietary Specifications: This
specifications call for desired materials,
producers, systems, and equipments by their
trade names and model numbers. For
detailed descriptions reference should be
made to manufacturer’s specifications.
19

2. Performance Specifications:
specifications which define products based
on desired end results which are
performance oriented; most appropriate
when new or unusual products or systems
are required or when innovation is necessary.
20

Cont’d…
 Example: traditional specifications for
asphalt pavement specifies the composition
of the asphalt material, the asphalt
temperature during paving, and compacting
procedures. In contrast, a performance
specification for asphalt would detail the
desired performance of the pavement with
respect to impermeability, strength etc.
21

Cont’d…
3. Reference Specifications: Specifications
which refer to levels of quality established by
recognized testing authority or standards set
by quality control authorities. These
specifications are also used in conjunction
with other types of specifications.
22

Cont’d…
4. Descriptive Specifications :
Specifications which describe all components
of products, their arrangements and methods
of assembly, physical and chemical
properties, arrangement and relationship of
parts and numerous other details. The
specifier shall take total responsibility for the
function and performance of the product.
23

Cont’d…
5. Cash Allowance Specifications:
Specifications meant to direct bidders to set
aside a specified amount of money to be
applied to the construction work at the
direction of the specifier.
24

Specification Writing
 Basically specifications are not to be created;
they are prepared based on existing
standards, codes, guidelines, and laws.
 Professionals involved could be qualified
Architects, Engineers, Quantity Surveyors,
Manufacturers etc.
 When specifications are to be written, the
following shall be taken into consideration:
25

Considerations:
a) Specification writing require:
1. Visualization (having clear picture of the
system)
2. Research (to know the legal impact
correctly)
3. Organizing (organizing what we know to
write the specification)
26

Cont’d…
b) Specification writing require professional
ability to read drawings.
c) Specification writing require wide
knowledge of the:
 construction materials,
 various levels of workmanship,
 different construction equipments and
 method of construction to be employed
27

Cont’d…
d) Specifications use simple and clear
language such that it can readily be
understood.
e) Specifications shall be brief and short as
much as possible (avoid long sentences
without punctuations)
f) Specifications shall include all items
affecting the cost of the work
28

Cont’d…
g) Specifications shall be fair
h) Specifications shall avoid repetition of
information shown on drawings to avoid
mistakes and duplications within the
specifications and drawings.
i) Specifications shall not include inapplicable
text and do not specify the impossible or
anything not intended to be enforced.
29

Cont’d…
j. Standard sizes should be compatible with
the market: ø 11
k. Specifications are written as in a language
that indicate what the work should be and
words “shall be” or “should be” are used.
l. As far as possible, the clauses of the
specification should be arranged in the same
order in which the work will be carried out.
30

useful references in specification writing?
1. Codes and ordinances of governments,
cities, or municipalities. For example, EBCS
2. Standards prepared by distinct societies and
government agents. For example, ACI
3. Standards or model specifications prepared
by manufacturers, professional
Societies, and government bodies.
31

4. Master specifications and previously
written specifications.
5. Information or experience acquired by
personal observation and contact with
trained or experienced people in the
construction industry.
32

Specification language
 The specification writer should present his
instructions in such a manner that: -
a) The drawings are more clearly interpreted,
not duplicated.
b) Rights, obligations, and remedial measures
shall be designated without ambiguity.
c) Clearly express the extent of works under
consideration.
33

Cont’d…
 the word choice used in this regard shall be: -
i) Judged by its quality not its length
ii) Should be concise and short and written with
commonly used words
iii) Punctuations are important but their usage
shall be limited to few
34

Cont’d…
iv) Capitalizing the first letters is mandatory for
the following expressions: -
a) Parties to the contract; e.g. Employer/Client
/Contractor/ Engineer
b) Space within the building; e.g. Bed Room,
Toilet, Living Room
c) Contract documents; e.g. Bill of Quantity,
Working Drawing, Specification
35

Cont’d…
v) Minimize pronouns, better to
repeat nouns
vi) Minimize the use of symbols
vii) Do not use foot notes, do not
underline within a sentence for
emphasis
36

37
….. contd
Substructure Super Structure
1. Excavation and Earth
works
2. Concrete works
1. Concrete works
2. Masonry works
3. Roofing works
4. Steel structures
5. Carpentry &joinery
6. Metal works
7. Finishing
8. Glazing
9. Painting

38
Who checks the Specifications
 When each job specification has been written, it must be
checked carefully to detect possible discrepancies,
deficiencies and errors. In doing so the consultant should
pay attention to the following:
 Does the scope of the work clearly define the extent and
limits of the work described in the specification?
 Are the references to the relevant drawings complete and
accurate?
 Are all the technical requirements clearly covered?

Cont’d…
 Do the requirements stated comply with all
statutory (or constitutional) rules and
regulations?
 Are all referenced standards correctly
identified?
 Is there any conflict or overlap with other job
specifications, particularly those prepared for
other disciplines?
39

Cont’d…
 Does the specification comply with the
overall criteria for the project?
 Does the bill of quantities prepared for
tendering completely cover the work under
the contract?
 Is the quality of presentation and the
completeness and clarity of the text
satisfactory?
40

41
Specification Faults
 Accuracy and clarity are the most
important in writing the specifications
since faulty specifications are the
frequent sources of dispute.
 Faulty specifications can be a cause for
extra expenditures or delays in
project implementation.

Cont’d…
 How can a faulty specification be a cause
for claims?
  When the specifications are not
prepared carefully, the contractor will
always find a way to claims.
42

Lec - 2.ppt ganbella university quantity estimta

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