measurement beng. 010-1
TRANSCRIPT
1
MEASUREMENT
OF
BUILDINGS
AND
CIVIL WORKS (CEQ 216)
2
COURSE OUTLINE
Measuring the quantities of building works and the use of SMM (BW)
Measurement of Building services and the use of SMM (BW)
Measurement of Civil Works the use of CESMM
Preparation of bills of quantities
Importance, requirements, definition and pricing preliminaries
Integrated Method of Assessment
Written examination, Course work and Assignment
Continuous Assessment Components 40%
Final Examination 60%
1. Two Assignments
2. Two Tests
3. End Semester Examination
References
1. Seeley I. (1993), Quantity surveying, Mac Millan Education Ltd London
2. N.A. Shah (1988), Quantity Surveying & Valuation, Khanna Publishers. Delhi
3. Seeley. I (1974) Building Quantities explained, Macmillan Press Ltd. Great
Britain,
4. Drawings of different structures.
5. SMM for building works
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INTRODUCTION When a person wants to build a house, he goes to an Architect or a Consulting
Engineer and places his requirements before him. After the Architect prepares the
plans to the owner‟s requirements, the owner‟s question is, as to what the house will
cost. If one wants to find out exactly what a house will cost, he has to take out the
quantities of the different items of construction involved in the house, and then,
assuming suitable market rates he has to arrive at the cost of the proposed house. The
subject of taking out the quantities, assuming suitable rates and working out the costs
of a house or any other civil engineering structure, is known as quantity surveying. This
Module will deal with one part of taking out the quantities of the different items of
construction involved in the house and other civil engineering works assuming that
other jobs (preparation of drawings and assuming suitable rates and working out the
costs have already done or will be done by the concerned parties.
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CIVIL ENGINEERING WORKS AND BUILDING WORKS Civil Engineering Works Vs Building Works There are two separate and distinct practice of measurement operating for civil
engineering works and building works such as:-
(i) Building works are generally measured in accordance with Standard Method
of Measurement (SMM) FOR East Africa
(ii) Civil Engineering works are generally measured in accordance with Civil
Engineering Method of Measurement (CESMM)
Methods of measurement in Civil Engineering Works and Building Works.
The comparisons between the two types of works that necessitate different method of
measurement are as follows:-
(i) Details in measurement
The details of building works are usually in a far more precise stage at
the time of preparation of Bills of Quantities than in the case of Civil
Engineering works.
Building works cover more trade/works sections and in consequence
subject to more detailed measurement. Much large number of items
has to be measured separately with various labors and other
incidental works itemized but this is not in civil engineering works, e.g.
in building works, backfilling trenches, leveling and compacting bottom
trench can each be measured separately, whereas in civil works, most
of these items are included in excavation rates. In Civil Engineering
works, one big item is deemed to include different other smaller items.
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(ii) Small rates
Some rates in building works are very small as a result of small items
measured separately.
(iii) Risk in pricing
There is a greater risk in pricing civil works than building works due to the
uncertainty nature of the works involved.
(iv) Variations
In building works, no much variations since almost all the items can be
measured with certainty. In the absence of variations in design most
building works with the exception of sub-structure, drainage and external
works will not be subject to re-measurements and the contractor will be
paid for the quantities incorporated in the Bills of Quantities.
(v) Bills of Quantities
Building work Bills of Quantities full describes and accurately represents
the works to be executes. If this cannot be achieved the works is described
as provisional or given a bill of approximate quantities. In the Introduction to
BW – SMM state that more detailed information than is demanded in the
documents should be given where necessary in order to define the precise
nature and extent of the required. CE BOQ – a list of items giving brief
identifying description and estimated quantities of the woks comprised in
contract.
In building contracts the specification is not a contract documents hence
the BOQ in building works is lengthier and more detailed than CE BOQ as
it contained the specification / preamble.
(vi) Mixed types of works
In some larger civil engineering contracts, there are also some building
works, take for example a large Power Station contract. The best
procedure would appear to measure the main superstructure, the
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supplementary buildings and probably the chimneys in accordance with the
SMM for building works. The reminder of the power station comprising
heavy foundation of piling, cooling towers, roads, sewers etc. are best
measured in accordance with CESMM.
(vii) Administration.
The structure of the team concerned with the construction of a civil
engineering project is similar to that for building works. In Civil engineering
works, the head of construction team is an engineer assisted by Resident
engineer while for buildings is an Architect assisted by the clerks of works.
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MEASUREMENT OF BUILDING WORKS
HISTORICAL BACKGROUND Measurement of building works is also known as quantity surveying. According to the
records available, the earliest quantity surveying firm to operate was in 1785 in the
United Kingdom (UK). In 1802, a number of Scottish quantity surveyors met and
produced the first method of measurement. Up to the middle of 19th century it was the
practice to measure and value the building work after it had been completed.
The architect was responsible for the creation of buildings as well as their design, and
he/she employed a number of master craftsmen who performed the work in each trade.
On completion each master craftsmen submitted an account for the materials used and
labor employed on the work.
The need of quantity surveyors became obvious for the following reasons:-
(i) Building work increased in volume.
(ii) Building owners became dissatisfied with the method adopted for settling the
costs of the work.
(iii) Some craftsmen were not conversant on the preparation of these cost
accounts and hence they engaged surveyors or measurers.
(iv) There were problems on making reconciling the amount of materials listed on
invoices with the measured quantity on the completed job.
(v) Some of the craftsmen made extravagant claims for the waste of material on
being worked on the site.
Due to the above reasons, general contractors became established during the period of
the industrial revolution and they submitted inclusive estimates covering the work of all
trade. Furthermore, they engaged surveyors to prepare bills of quantities on which their
estimates were based.
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As competitive tendering became more common the general contractors began to
combine to appoint a single surveyor to prepare a bill of quantities, which all the
contractors priced.
In addition, the architect on behalf of the building owner usually appointed a second
surveyor, who collaborated with the surveyor for the contractors in preparing the bill of
quantities, which was used for tendering purposes.
In later years, it became the practice to employ one surveyor only who prepared an
accurate bill of quantities and measured any variation that arose during the progress of
the job. This was the origin of the independent and unbiased quantity surveyor as he
operates today.
COMMON TERMS:-
1. Standard Method of Measurement (SMM) - This is document which provides a
Uniform basis for measuring building works and it represent the essentials of
good practice. It provides the rules of measuring all items in building works. Also
provides the units of items such as cubic, square, linear etc.
2. Taking off – measuring of quantities in which the dimensions are scaled or read
from drawings and entered in a recognized form or specially ruled paper, called
“dimension paper”.
3. Quantities – refers to the estimated amounts of labour and materials required in
the execution of the various items of the work and together these items give the
total requirements of the building contract.
4. Contractor – Is a person or corporate body whose bid to carry out the works
has been accepted by the employer and eventually engaged to undertake the
works.
5. Employer - Is the party who employs the contractor to carry out the works.
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6. Provisional Sums – works which cannot be measure accurately during taking
off. It is a sum provided for work or for costs which cannot be entirely foreseen,,
defined or detailed at the time tendering documents are issued. Examples are
such as testing of materials, progress photographs and contingencies. The sum
is to be used under instruction.
7. Prime Cost Sum (P.C) – Cost for works provided by nominated sub contractors
for example, electrical installations, telephone installation, lifts installation etc.
Since this is a specialist work carried out by persons other than the general
contractors provision is to be made for profit to the general contractor and for
attendance.
8. Preliminaries - items in the bill of quantities entered for the purpose of setting
out all general liabilities and obligations of the contractor. These are items
required to be executed pre-commencement of the actual required work, during
the work and after the work completion.
9. Variations- the alterations or modifications of the design, quality or quantity of
works as shown upon the contract drawings and described by or referred to in
the contract bills. This includes the additions, omissions or substitution of any
work or the alteration of the type of standard or any materials.
10. Preambles – able clauses inserted at the head of each work section bill
covering matters relating to the specific work section that should be brought to
the attention of the estimator as they will affect the rates that he inserts against
billed items of measured work.
11. Bills of quantities – a fully described and accurately representation of the
works to be executed. Bills of quantities consist of preliminaries, prime cost
sums, provisional sums and measured works.
12. Ditto/do: that which has been said before/above.
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MEASUREMENT PROCEDURES In any measurement there are a number of essential factors that should always be
considered and applied to follow good established practice as follow:-
1. Examine the drawing carefully to become familiar with the work and to identify
any parts where information is lacking.
2. Interpret carefully and apply in a sound and logical way of provisions in Standard
Method of Measurement of building works. (SMM).
3. Ensure a high standard of accuracy in dimensions.
4. Make full use of sub-headings throughout the dimensions to facilitate
identification and waste to preliminary calculations, explanatory notes and
location description.
5. All descriptions should be adequate, concise and written in a logical and easily
understood format following the sequence adopted in SMM.
6. Adopt a logical sequence of items so that each one following the preceding one
in a natural progression.
7. Seek to achieve a good standard of presentation.
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GENERAL PRINCIPLES OF TAKING – OFF
1. General rules:-
Bills of quantities shall fully describe and accurately represent the works
to be executed. The billed description is to be comprehensive and
sufficient to enable the estimator to fully understand what is required and
to give a realistic price. Those works whose extent cannot be
determined with reasonable degree of accuracy should be described as
“Provisional”.
Works are to be measured net as fixed in position each measurement are
to be taken to the nearest 10mm i.e > 5mm regarded as 10mm while <
5mm are disregarded.
Openings under the measured area shall be deducted.
The order of stating dimensions in descriptions shall be consistent and
generally in the sequence of length, width and height.
Billed items are generally “deemed to include” i.e. without the need for
specific mention of labour; materials unloading, storing handling, fixing,
use of plant, waste of materials, square cutting, establishment charges
and profit – it is essential that the estimator is fully aware of all these
items as he must include for them when building up unit rates.
Work under water shall be so described stating where canal, river or sea water and the levels of high and low water.
Work in compressed air shall be so described.
2. Dimension paper:
Measured items, scaled or taken from drawings are entered on a special paper
known as „dimension paper‟. This dimension sheet is split into two identically
ruled parts each consisting of four columns as follows:-
1
2
3
4
1
2
3
4
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Key: Column 1 – “Timesing column” Multiplying figures are entered when there
is more than one of the particular items being measured.
3/ 5.00
This means that the length of 5.00m of the same item appears three times in the measured drawing
Column 2 – “dimension column”. Actual dimension as scaled or taken direct
from the drawing are entered here.
5.00
The length 5.00m is in “dimension column”.
Column 3 - “Squaring column”. The length, area or volume obtained by
multiplying the figures in columns 1 & 2 is recorded.
3/ 5.00 15.00
15.00m is in Squaring column”. This is the result of multiplying column 1 and 2
Column 4 – “Description column”. In which the right description of each
item is entered. Also, the right hand side of this column is used
to accommodate preliminary calculations and other important
information.
3/
5.00
15.00
3.00 1.50 0.50 5.00 Hor. Dpc. 110mm wide of single layer of Hessian base bit. to B.S. 743 Lapped 100mm at jts and bedded in c.m (1:3)
Hor. Dpc……………….. are in “Description column”.
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1. Entering of Dimensions:- (a) Order of Dimensions- For convenience a constant order of entering
dimensions should be maintained throughout i.e (i) length, (ii) breath or width,
(iii) depth or height.
For example: Concrete item is measured in cubic meter. Say concrete with 10m
long, 690mm wide and 230 deep will be entered as follows:-
10.00 0.69 0.23
Conc. Grade 20 in foundations
(b) Spacing of items - It is essential that ample space is left between all items
on the dimension sheets so that it is possible to enable any items which may
have been omitted when the dimensions were first taken off to be
subsequently inserted without cramping the dimension disproportionately.
10.00 0.69 0.23
4.00 0.69 0.23
Conc. Grade 20 in foundations
(c) Waste - The right hand side of the description column is used for
preliminary calculations, built up lengths, explanation notes, location of
measured work etc. This should not be overlooked. All steps that have been
taken in arriving at dimensions, no matter how elementary or trivial they may
appear should be entered in the waste section.
(d) Timesing – If there were five such items, then this dimension would be
multiplied by five in the timesing column:-
5/ 10.00 0.69 0.23
7.94
Conc. Grade 20
in beds
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(e) Grouping of Dimensions
(i) Where the same dimension applies to more than one item the best
procedure is to segregate each of the separate description by & sign and to
bracket the descriptions.
100.00 50.00
Site clearance by removing up bushes, shrubs and the like including grubbing up their roots & Exc. O`site av. 150m deep to remove all veg. matter wheel 20m then spread and level.
20.00 18.00
100 mm thick bed of conc. (1:2:4/20 mm apg) laid on ashes (m/s)
& 50m thick bed of ashes laid and consolidated to rec. cons. bed incl. levllg and compactg grd.under
(ii) Where more than one set of dimensions relate to the same
description, the dimensions should be suitably bracketed.
25.00 3.50 17.00 3.50 15.00 3.50 10.00 3.50
21.10 20.30 15.10 12.50 18.75 10.00
230 mm bwk laid &
jtd in c.m (1.3)
Exc o’site av.
150mm db to
revome all
veg. matter
wheel 20m
then s &l
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(f) Abbreviations
Abbreviations are used in the description space in order to save space and time.
There are standard and acceptable abbreviations used in measurement such as
follows:-
conc. - Concrete a.b - as before a.b.d - as before described n.e - not exceeding bldg - building B.S - British Standard Bwk - Blockwork Ddt - Deduct
b & j - bed and joint bott. - Bottom (g) Deductions
After measuring an item of construction it is sometimes necessary to deduct for
voids or opening in the main area or volume.
When measuring areas of excavation, concrete oversite, blockwork etc the best
practice is to measure the full area in the first instance and, subsequently adjust
for any voids or openings. e.g Adjustment for blockwork are done when “taking
off the windows & door openings.
21.30 20.30
5.00 4.50 2.00 2.00
Exc. o`site av. 150m dp to remove all veg. matter wheel 20m then S & L
Ddt ditto
Note: underline the word Ddt
3/ 2.10
0.90
Ddt: solid bllockwall
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2. Measurement of Irregular figures It is often necessary to measure the areas of triangles and circles, the
circumferences of circles and volumes of cylinders, etc., and the usual method
of entering the dimensions is illustrated in the following examples:
½/ 22 7 ½ /2/ 22
7
22 7
4.00 3.00
2.00 2.00
2.00
0.50 0.50 3.00
3. Alterations to dimensions
It is sometimes necessary to substitute amended dimensions in place of those
which have already been entered on the dimension paper. It is advised never to
alter the original figures, as apart from looking most untidy it is often extremely
difficult to read between the lines the correct figures. If it is necessary to amend
figures the better procedure is to cross out the original figures and neatly write
the new figures above them.
Where it is required to omit dimensions which have previously been recorded
the easiest method is to write the word “nil” in the squaring column as shown in
the following example.
Area of triangle with a base of
4m and a height of 3m
(area=½base x height)
Area of circle with 2 m radius
(area = πr2)
Circumference of semi-circle
with 2 m radius (circumference
of whole circle = 2πr) Volume of cylinder, 1 m
diameter and 3 m high.
(area of circle x height of
cylinder)
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23.50 0.75 0.80
8.20 0.75 0.80
|
Nil
|
Exc. fdn. tr. n.e. 1.50m dp.comm.at stripd.level
&
Backfill exc. mat. ard. fdns
4. Figured Dimensions
When taking-off it is most desirable to use figured dimensions on the drawing in
preference to scaling, as the drawing are almost invariably in the form of prints,
which are not always true-to-scale. It is sometimes necessary to build-up overall
dimensions from a series of figured dimensions and this work is best set down in
“waste” on the right-hand site of the description column.
5. Number & titles of dimension Sheets
a. Sheets should be suitably headed with the title and section of the job at
the top and numbered at the bottom. Example Drawing 10, doors section
can be seen as below.
CONSTRUCTION OF PHYSCIS LABORATORY –Drwgs,,,,,,,,,,,,,,,,,,,,,,,,,
.
Site Clearance
1.1
.
Doors
10.1
b. At the top of the first dimension sheet for a job, it is good practice to enter
a list of the drawings from which the measurements have been taken with
the precise drawing number of each contract drawing carefully recorded.
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6. Order or “Taking – off”
The order of “taking off mostly follows the order of construction. In simple
building the order of taking off would probably be as follows:-
a. Site clearance
b. Foundations
c. Blockwork
d. Floors
e. Roof
f. Finishing (Plaster, ceiling & floors )
g. Windows
h. Doors
i. Fittings
j. Plumbing installation
k. Drainage work
l. Other services (electrical etc)
m. External works (roads, paths, fences and grassed areas)
7. Descriptions
a. General requirements – description must abide with or cover all matters
detailed in the SMM and include all information which the estimator will
require to build-up a realistic price for the item in question.
b. Order of wording – the first few words of a description should clearly
indicate the nature of the item being described.
c. Number of units – in some cases it necessary to give the number of units
involved in a superficial or linear item, in order that the estimator can
determine the average area or length of unit being priced.
4/
20.00 3.00
230mm Thick c&s solid blockwall ……...
excavations
concrete footing
blockwork
hard core
Concrete bed
cover bed
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8. Query Sheet
When “taking – off” any doubt/queries will be forwarded to the architect on
query sheets normally divided down the centre to accommodate the queries on
the left-hand side and the answers on the right hand side. During examinations
the candidate will have to decide the queries as they arise, but it will often be
desirable for him/her to indicate briefly in “waste” why the has adopted a
certain cause of action.
QUERY SHEET
S/N QUERY ANSWER
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SUBSTRUCTURES
The Substructure of any building is a base or the underneath or the foundations of that
building. Building construction can be divided into two faces namely,- the Substructure
and the Superstructure. The constructions after the foundations are of the
Superstructure.
MEASUREMENT OF EXCAVATION & FOUNDATIONS
It is very important to that the „taking off‟ process is done in logical order. This simplifies
the process and reduces the risk of omission of items.
A. EXCAVATIONS
In a small building, a satisfactory order of items would be as follows:-
1. Site clearance/site preparation this will include:-
(i) Site preparation generally including anti-termite treatment if any. This is
given in square meters.
(ii) Excavating vegetable soil - This normally forms the first item in the
„Excavation‟ section of the Bill. The area is measured in square meters to
the extremities of the foundations and the average depth, often 150mm, is
included in the description together with the method of disposal on the
site.
15.00 12.00
Exc. veg. soil, av.150mm dp. & dep. on site in spoil heaps, av. 20 m from excavn
(iii) Removing trees and hedges SMM D4
(iii)(a) Cutting down trees and grubbing up their roots shall be enumerated in
groups stating their girth starting with 600mm. girth and in further
stages of 300mm.
10
Cutting down small trees n.e 600mm girth and grubbing up their roots
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(iii)(b) Cutting down hedges and grubbing up their roots shall be given in
linear meters stating the nature and height of each hedge or its location.
15.00
Cutting down Michongoma hedges and grubbing up their roots.
(iii)(c) Clearing site of bushes, scrub, undergrowth and the like and grubbing
up their roots shall be given in square meters or hectares.
15.00 12.00
Clearing site of bushes, scrub, undergrowth and the like and grubbing up their roots.
2. Excavation and Earthworks:- SMM D5 – D15
(i) Excavation to reduce levels - Where the site is sloping and further
excavation is required to reduce the level of the ground down to the specified
formation level, this excavation is measured as surface excavation in square
meters when not exceeding 300mm in depth, otherwise in cubic meters.
Measurement of Earthwork
The following is an example of measuring the volume of earthworks on
sloping sites:
It is frequently difficulty in measuring the volume of earthworks, particularly
on sloping sites. The following examples are designed to indicate the main
principles involved and generally clarity the method of approach.
Sloping site excavation
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The quantity surveyor is often called upon to calculate the volume of
excavation and /or fill requirement on a sloping site and the following
example indicates a comparatively simple method of approach.
12m
12m
Assuming that in the example illustrated above, it is required to excavate
down to a level of 2.00m, including excavating vegetable soil to a depth of
150 mm. In this case the whole of the site is to be excavated.
The average depth of excavation over the site is most conveniently found by
suitably weighting the depth at each point on the grid of levels, according to
the area that each level affects. This involves taking the depths at the
extreme corners of the area once, intermediate points on the boundary twice
and all other intermediate points four times. The sum of the weighted depths
is divided by the total number of weightings (number of squares x 4) to give
the average weighted depth for the whole area. This method can only be
used when the levels are spaced the same distance apart in both directions.
2.500 3.000
2.750 3.000 3.250 3.500
3.500
3.750 4.000
r
r
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The volume in this example is now calculated:
Corner depths 2.50-2.00= 0.50 3.00-2.00= 1.00 4.00-2.00= 2.00 3.50-2.00= 1.50 Depths at intermediate 2.75-2.00=0.75x2= 1.50 point on boundary 3.00-200=1.00x2= 2.00 3.50-200=1.50x2= 3.00 3.75-200=1.75x2= 3.50 Depth at centre point 3.25-2.00=1.25x4= 5.00
Sum of weighted depths 16) 20.00 Average total depth 1.25
less vegetable soil 0.15 average adjusted depth 1.10m
The dimensions would then appear as follows:
12.00 12.00 12.00 12.00 1.10
Exc. veg. soil, av.150mm dp. & dep. on site in spoil heaps, av. 20 m from excavn Exc. surf. to red. levels.
& Remove from site
(ii) Excavation of foundation trenches – Foundation trench excavation is
measured in cubic meters in 1.50m stages of depth, stating the starting
level of excavation, which is usually stripped level. For example for
foundation trench 2m deep below the stripped level will have to be split in
two sections:-
(1) Not exceeding 1.50m deep, and (2) Exceeding 1.50m deep and not
exceeding 3.00m deep. It is advisable to separate the trenches to
external and internal walls.
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Excavation in rock and in silt or running sand shall be given in cubic
meters as extra over all kind of excavations irrespective of the depth.
These are to be separated from normal excavations because they have
different cost implication during pricing.
Example: Excavation of foundation trenches
22.50 0.75 1.50 22.50 0.75 0.50
Exc. fdn. tr. n.e 1.5m. dp starting at stripped lev.
& Backfill exc. mtls. ard. Fdns Ditto .exc/over 1.5m. dp
but n.e 3.0m dp starting at stripped lev.
& Backfill exc mtls. ard. fdns
22.50 0.75 1.00 22.50 0.75 1.00
Extra over exc. in rock & Backfill exc. mtls. ard. Fdns Extra over exc. in running silt & Backfill exc mtls. ard. Fdns
Girth of Buildings e.g Rectangular buildings
Girth is a perimeter of a building. This length is required for foundations, external walls
etc. also it is a base to calculate dimensions for trench excavation, planking and
strutting, concrete in foundations, blockwork and damp proof course.
Example
10.00m
20.00m
Say 230mm wall
25
59.08 0.70 1.20
Girth l = 20.00 w = 10.00 sum of l & w 2/30.00 sum of all for sides – 60.00 less corners 4/230 - 0.92 girth of bldg 59.08
Fdn depth – 1.20m Fdn width – 700mm
Exc. fdn. tr. n.e 1.5m. dp starting at stripped lev.
& Backfill exc. mtls. ard. Fdns
Working space allowances. D5 (f)
Note: The working space is required if the face requires formwork. All
reinforced insitu concrete require formwork hence working space should be
provided.
For insitu plain concrete footing, concrete is poured against the sides of
trenches hence no working space is required.
(a) Working space of 0.30 from the face work requiring the formwork not
exceeding 1m high
(b) 2m for trenches to receive post tensioned concrete ground beams
(c) 1m for work which is over 1m high from below the starting level of
excavation
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formwork
690mm
Width of foundation trench = 0.69
Add working space allowance = 2/0.30 0.60
Total width 1 .29
(iii) Excavation of pits for column bases (if any)
Excavating pits to receive columns, isolated piers and the like are given in
cubic meters stating the starting level and the depth. Allowances for
working space are to be considered depending on the depth of pits and
the formwork requirements.
For example, a column of 1.50m height and 1.00m base can be recorded
as follows:-
3.00 3.00 1.50
Exc. column pit. n.e
1.5m. dp starting at stripped lev.
& Backfill exc. mtls. ard. Fdns
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3. Disposal of excavated materials
(a) Disposal of excavated materials – Except in case of vegetable soil, the
subsequent disposal of the excavated material forms a separate billed item,
either of soil to be backfilled or to be removed from site. In the first instance,
when measuring the trench excavation, it is usual to take the full volume as
backfill.
22.50 0.75 1.50
Exc. fdn. tr. n.e 1.5m. dp starting at stripped lev.
& Backfill exc. mtls. ard. Fdns
(b) Surplus spoil is given in cubic meter. Either deposited on site in
permanent spoil heaps or spread on site shall be so described stating the
location or the average distance from the excavations.
22.50 0.75 1.50
Remove from site and
deposit on site in permanent spoil heaps 100m away from excavations
(c) Earth filling to make up levels:-
If the filling is over than 300mm thick shall be given in cubic meters and
for the filling less than 300mm thick, shall be given in square meters
stating the average thickness.
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20.00 15.00 0.45
Imported sand to make
up levels
20.00 15.00
Imported sand 280mm average depths to make up levels
4. Leveling and compacting trench bottoms
Surface treatment including leveling and compacting – This is done at the
bottom of excavations to receive concrete. Ii is measured in square meters.
22.50 0.75
L. & C. bott. of excns.to rec. conc.
5. Disposal of water
Disposal of water –This is done to keep excavation free from water and is
given as item
Item
Allow for keeping excavations free from general water
6. Planking and strutting
Planking and strutting - Earthwork support which include the use of timber
Planking and strutting to uphold the sides of excavation, plywood trench
sheeting and light steel trench sheeting and strutting. It is measured to the
sides of trenches and given as an item. section D19 or can be measured in
square meters
Item
Planking and strutting to uphold the sides of excavations
23.00 1.20
Planking and strutting to uphold the sides of excavations
29
B. MEASUREMENT OF FOUNDATIONS
When the excavation is complete, the excavated trench is filled with foundations
which include:-
1. Concrete in foundations including adjustment shall be given in cubic
meters as stating the mix and thickness (SMM F3). The adjustment of
excavated soil disposal will be taken with this item (i.e. Ddt. Backfill and
Add. Removal from site)
20.00 0.75 0.23
3.45
Conc.(1:3:6/40mm agg) in fdns. & Ddt. Backfill & Add. Remove from site
10.00 0.75 0 .23
1.725
Conc.(1:3:6/40mm agg) in fdns. & Ddt. Backfill & Add. Remove from site
2. Reinforcements – Bar reinforcement will be entered by length on the
dimension sheets and are billed in kilogrammes. (Section F16)
Weights of Groups of Bars per Metre
Size (mm)
Number of Bars
1 2 3 4 5 6 7 8 9 10
6 0.222
0.444 0.666 0.888 1.110 1.332 1.554 1.776 1.998 2.220
8 0.395
0.790 1.185 1.580 1.975 2.370 2.765 3.160 3.555 3.950
10 0.616
1.232 1.848 2.464 3.080 3.696 4.312 4.928 5.544 6.160
12 0.888
1.776 2.664 3.552 4.440 5.328 6.216 7.104 7.992 8.880
16 1.579
3.158 4.737 6.316 7.895 9.474 11.053
12.632
14.211
15.790
20 2.466
4.932 7.398 9.864 12.330
14.796
17.262
19.728
22.194
24.660
30
25 3.854
7.708 11.562
15.416
19.270
23.123
26.978
30.832
34.686
38.540
32 6.315
12.630
18.945
25.260
31.575
37.890
44.205
50.520
56.835
63.150
40 9.866
19.732
29.598
39.464
49.330
59.196
69.062
78.928
88.794
98.660
31
Example: If the foundation footing is reinforced with mild steel bars, the
measurements and entries will be as follows:-
4/ 4/ 4/
8.50 4.00 3.80
34.00 16.00 15.20
34.00 16.00 15.20 65.20 12mm dia. Mild steel bars in fdn footing
65.20x 0.888kg/m = 57.8976 Say 58kg
3. Formwork section F19
Formwork for most of the surfaces are given in square meters classifying
them in groups according to the position requiring formwork.
4. Blockwork/ walling (SMM G) in foundations is measured in square meters
stating the thickness, mix of mortar for bedding and jointing. The
adjustment of excavated soil disposal will be taken with this item (i.e. Ddt.
Backfill and Add. Removal from site)
Example: Measurement of blockwork
8.00 1.20
9.60
230mm blk b & j in c.m (1:3) & Ddt. Backfill 9.6 x 0.23 = 2.208 & Add. Remove from site 9.6 x 0.23 = 2.208
32
Example
10.00m
57.20 1.19
Girth l = 20.00
Less sprd 2/235 0.47 19.53
w = 10.00
Less sprd 2/235 0.47 9.53
sum of l & w 2/29.06 sum of all for sides – 58.12
less corners 4/230 - 0.92 Length of blkwk 57.20
Blkwk thickness– 230mm depth – 1.19
230mm blk b & j in c.m (1:3) & Ddt. Backfill ……x 0.23 = ………….. & Add. Remove from site …….. x 0.23 = ……………..
5. Damp proof course – Normally measured in linear meter. The description
of Damp proof course must include particulars of materials used,
thickness/gauge, number of layers and the nature of bedding (section
G96 –G97)
20.00m
Say 230mm wall
33
Example: Measurement of Damp proof course
80.00
Hor dpc 110mm wide of single layer of Hessian base bit. To b.s.743. lapped 100mmat jts &bedded in c.m (1 3)
Solid floors
(a) Ground floor consisting of a concrete bed usually supported on a bed of hardcore
Hardcore – This is measured as equal to the area of the void being filled (D20 in
SMM). It is measured in square meters if it does not exceed 300mm
thick, otherwise it is in cubic meters.
Damp proof membrane – This is laid on top of the hardcore and normally
measured in square meter. The description of Damp
proof membrane must include particulars of materials
used, thickness/gauge, number of layers and the
nature of bedding (section G96 –G97)
Example: Measurement of Hardcore & Damp proof membrane
4.50 5.70
Hardcore filling av.150mm. th., consisting of gravel rejects, blinded to receive conc. Including levellg and compacting. & Polythene hor. Membrane not less than 0.125 mm th., lapped 100mm at jts. & laid on hardcore
Concrete bed – Rarely exceeds 300mm in thickness and so are normally
measured in square meters stating the thickness. (SMM. section F5)
34
Example: Measurement of Concrete bed
4.50 5.70
25.65
1oomm th.conc. bed (1:2:4/20 agg.)
(b) Upper floors consisting of suspended concrete slabs. (SMM. section F7 (a))
Suspended floors and the like shall be given in square meters stating the
thickness.
The floors will be measured together with the associated items such as
reinforcements Section F16 and formwork section F19
35
SUPERSTRUCTURES
Superstructure elements of any building are those constructed on top of a base or of
the foundations of that building. Building construction can be divided into two faces
namely,- the Substructure and the Superstructure. For a simple building, superstructure
elements are such as walling, roofing, floors, doors, windows, staircases, fittings,
electrical installation, plumbing installation etc.
WALLING (SMM SECTION G)
Walling can be of blocks, bricks, concrete, natural stones and other light materials
recommended be the design team to be used for walling.
MEASUREMENTS
It is essential to measure the wall in a sequential order starting with external wall,
internal wall together with their incidental works if any.
(a) Particulars of the following shall be given:-
(i) Material, kind, type, finish and size of blocks shall be so described.
(ii) Any requirement as to the stone and the quarry
(iii) Type of bond for blockwork
(iv) Composition and mix of mortar for bedding and jointing
(b) External walls The length of external walling will be obtained by the method of girthing and the
height will normally be taken up to some convenient level, such as the general
eaves line. Any additional areas of the external wall such as gables parapets, wall
up to higher eaves level, etc, will be then taken off.
In measuring the wall the measurer takes the whole area regardless that there are
some voids and the adjustment of wall for window and doors openings will be made
when measuring the windows and doors.
36
The measurement of areas of external walls will be followed by incidental labours,
etc, such as rough cutting, eaves-filling, projecting courses etc.
(c) Internal walls
The measurement of external wall is usually followed by the internal walls. A careful
check should be made on the type and thickness of each partition, and where there
are a number of different types of partition it is often helpful to color each type in a
different color on the floor plan. Internal wall is also measured in square meters
stating all essential particulars as before described.
MEASUREMENT OF ROOFS - (SMM SECTION J, K AND SECTION L
Roofs are of two types namely; Pitched roofs and flat roofs. Both types can
conveniently be subdivided into two main sections for purposes of measurement, i.e.
construction and coverings. The order of measurement of these two sections varies in
practice, but on balance it is probably better to take the construction first as this follows
the order of construction on site.
PITCHED ROOFS
(a) Construction
The order of items should follow a logical sequence such as plates, rafters, ceiling joist,
collars, purlins, struts, ridge boards, and hip and valley rafters.
(i) a Timber works
The roof timbers such as rafters, ceiling joist, collars, purlins, struts, fascia
board, barge board, hip and valley rafters are all measured in linear
meters stating the size (thickness x width)
37
60 50 50
25X250mm hardwood/softwood timber Fascia board 150x150mm h/wd Wall plate 50x100mm swd ceiling joist
Size – Thickness x Width
Kind and quality of timber
Preliminary treatment of timber ( e.g. Pressure impregnated) The quantity of timber required can be calculated by various formulas:-
For example, L/S - 1 = number of Trusses
L = Length
S = Spacing of Truss
Now if the length is 18m and the spacing of rafters is 1.5m, then the number of Trusses
will be 18/1.5 - 1 = 11 Trusses
18m Hipped ends Ni of Trusses 7m L/S -1 =11
18m No of Trusses = Gable ends L/S + 1 18/1.5 +1 = 13
38
18m
One Hipped end and No of Trusses One Gabled end L/S 18/1.5 =12 If the length of rafters is calculated as 5m in each side, then the „taking off‟ will be as follows:-
11/2/
5.00
50X150mm Rafters
(i) b Lengths of Rafters
Where roof sections are drawn to a sufficiently large scale, the easiest method is
to scale the length of rafter off the drawing, taking the length from one extremity
to other of the rafter.
Another alternative is to calculate the length by multiplying the natural secants of
the angle of pitch by half the total span of the roof. The natural secants of the
more usual pitches of the roof are as follows:-
The use of four figure mathematical table for values of natural secants is
recommended.
Pitch of roof 15° 30° 40° 45° 50° Natural secant 1.036 1.155 1.305 1.414 1.555
39
40° 4.175m Half total span of roof is 4.175m, and the secant 40° is 1.305, therefore, Length of rafter = 4.175 x 1.305 = 5.448m (b) Coverings Roof covering are of various types such as slates or tiles, corrugated or toughed
sheets, thatch, bitumen felt , etc.
Slates or Tile roofing (SMM K2 -K15)
Particulars of the following shall be given:-
Kind, size, type and quality of slates or tiles
Extent of lap
Method of fixing and the number of nails or pags per slate or tile
Size and type of laths or battens
Measurements:-
Roof coverings shall be measured in square meters
40
Square cutting around openings, raking cuttings , curved cuttings, valleys, hips
and vertical angles shall be given in linear meter separately.
Corrugated or troughed sheets SMM K16 –K26
Particulars of the following shall be given:-
Kind of sheeting
Quality and gauge of sheeting and type
Extent of side and end laps
Nature and general spacing of the structural supports ( eg. Purlins)
Method of fixing the sheeting
Roof coverings shall be measured in square meters
Measurements:-
12.00 6.00
26 Gauge (SWG) Corrugatted Alumium roofing Sheet 150mm both sides and ends laps fixed to timber purlins with galv. Screws and plastic washers
Square cutting around openings, raking cuttings , curved cuttings, valleys, hips
and vertical angles shall be given in linear meter separately.
FLAT ROOF COVERINGS (a) Asphalt (SMM SECTION J)– The main areas of asphalt are measured in square
meters stating the thickness and number coats of asphalt. Furthermore, the asphalt
item is to include the underlay of felt, cork, fiberboard or similar material and any
reinforcement.
(b) Bitumen felt (SMM K36) – The unit of measurement is the square meter and it is
classified by slope. Full particulars of felt are to be given such as extent of laps, nature
41
of base and method of securing felt to it and the nature of surface treatment if any. The
measurement of the main areas of roof covering will be followed by such linear items.
FINISHING (SECTION S)
Major Finishing classifications are walls, floors and ceiling. The classifications depend
on which kind of materials eg.
-Cement sand screed
-Terrazo
-Ceramic floor tiles etc
Materials can be further grouped into:-
- Insitu finishing
- Tiles, slab, block finishing
- Plain sheeting finishing e.g plywood, soft board
They should be stated either
- Internal finishing work or
- External finishing work
INSITU FINISHINGS
A) SAND & CEMENT SCREED FINISHING
(i) Composition and mix ratio ( i.e, 1:3, 1:4)
(ii) Thickness – 20 – 60mm thick ( common 40mm)
(iii) Number of coats normally laid one coat
(iv) Nature of surface treatment such as
- wood floated
- Steel trowelled smooth
- Nature of base eg. Concrete blockwork background
(v) Preparatory work so as to form keys e.g. hacking concrete
(vi) Any other special curing on finishing such as steam curing, should be given in
your description
42
Typical description
40mm Thick cement and sand screed (1:3) steel trowelled smooth laid to floor to
keyed concrete base.
B) TERRAZO FINISHING
(i) Composition and mix ratio
1st coat consist of cement and sand screed (1: 3), (1: 4), (1: 6)
2nd coat consist of cement marble chipping white or any color 1 :21/2
(ii) Thickness 20 – 60mm thick ( minimum thickness is 16)
(iii) Number of coats – 2coat or 1coat it the thickness is less than 30mm
(iv) Nature of surface treatment
- Grind the surface
- Polish the surface
(v) Nature of base – concrete, blockwork or brickwork
(vi) Special curing
Typical description
40mm Thick terrazzo to floor to keyed concrete base in two coats 1st coat of
20mm thick (sand and cement 1:3) 2nd coat of 20mm coloured and marble
chipping 1:21/2) includind grinding the surface and polishing.
Floor and paving (S 3)
- Horizontal floor and paving , cross falls and slopes not exceeding 15 degrees from
horizontal shall be given separately in square meters
Ceiling Finishing (S 4)
Work to walls and ceilings shall each be given separately in square meters describing if
to battering walls, to sloping walls etc.
The area of ceiling is measured between wall surfaces in square meters, followed by
any associated labor such as arises to beams.
43
Wall Finishing (S 4)
The measurement is taken from the floor to ceiling. Work behind wood skirting and the
like shall be dealt with the work of walls disregarding any ground.
Skirting and picture rails (S.8)
Timber skirtings and picture rails as well as cornices, fillets etc. are measured in linear
meters stating the size and describing the labours and including any supporting
grounds.
Dividing strips S. 7
Dividing strips are given in linear meters stating end, angles and intersections shall be
deemed to be included with the item.
Schedule of finishings
Location
Floor
Skirting
Walls
Ceiling
RI
40mm Terrazzo
150X20 Terrazzo
Plaster
Plaster
R2
Ditto
Ditto
Ditto
Ditto
R3
40mm. C & S Screed
150x20 C & S Screed
Ditto
Ditto
R4
Ditto
Ditto
Ditto
Ditto
44
R1 R2 R3 R4
230 230 230 230 230 3000 3500 4000 4000
45
2/
5.00 3.00 5.00 3.50 4.00 5.00
FLOOR FINISHING 40mm. thick terrazzo floor finish
laid to falls and cross falls n.e 15 degree from horizontal to keyed conc. Base in 2 coats 1st coat of 20mm thick c & s (1:3) 2nd coats of 20mm coloured cement and marble (1:21/2) and including grinding the surface with carborundum and polishing internally (R 1)
40mm thick Terrazzo floor finish
laid to keyed conc. base in 2 coats ditto. (R2)
40mm thick Steel toweled smooth laid to floor to keyed concrete R (3 & 4)
WALL FINISHINGS (R(1& 2)
ht = 3.00 Less floor 0.04 Less Skirting 0.15 0.19
Finishing ht 2.81
(R(1& 2) Ht = 3.70 Less 0.19 3.51
2/ 2/ 2/ 2/ 2/2 2/2
3.00 5.00 3.50 5.00 4.00 5.00
SKIRTING 20mm thick x 150
mm high terrazzo skirting with top rounded edge and covered junction with paving in one coat in white and cement marble (1:21/2) to blockwork / concrete work background including grinding with carborundum stone and polishing to the surface.
20mm thick x 150
mm high cement and sand screed (1:3) skirting to blockwork/ – concrete work background.
R (3 8 4)
CEILING FINISHING 15 mm thick plaster to concrete ceiling in two coat 1st coat 12mm thick in cement, sand and line ( 1: 4: 5); 2nd coast 2mm thick in cement sand and line putty (1: 1: 5) with wood floated surface internally.
46
2/ 2/ 2/ 2/ 2/2 2/2
3.00 2.81 5.00 2.81 3.50 2.81 5.00 2.81 4.00 3.51 5.00 3.51
15mm thick plaster to
blockwork/ concrete work or brickwork walls in two coats, 1st coat 12mm thick in cement, sand and lime (1:4:5) 2nd coat 3mm thick.
& 3mm thick in cement, sand
and lime putty ( 1:1:5) with wood floated surface internally
47
DOORS AND WINDOWS - SECTION M
A. DOORS Door shutters The measurement of doors can be subdivided into internal and external doors, and the
dimensions of each of these two classes of door broken down into;
1. Door
2. Adjustment of opening
Measurements
Doors shall be given in square meters stating the thickness and the number of
doors (each leaf being counted as one door).
Doors may also be enumerated stating the size Classification
(i) Flash doors stating the construction of the core, the finished thickness of the
door, the kind, quality and the thickness of the facing materials and the method
of fixing of facing material to the core.
(ii) Boarded doors stating the thickness of the boarding, ledges, braces and
framing and the method of jointing the board covering or filling.
(iii) Panelled doors stating the nominal thickness of the framing, the number and
nominal thickness of the panels and where molded stating whether the moldings
are worked on the solid or planted on and whether on one or both side.
Pannelled doors with open panels for glass shall be so described.
48
Door frames and linings
Door frames and linings are measure in linear meters giving full description of all the
labours and the size of the member.
Adjustments
When adjusting the opening for care must be taken to cover all the appropriate items
by adopting a logical order of „taking off‟ such as deduction of walls, external and
internal finishings, - skirting, and flooring
Sundries
Plugging - Plugging to concrete, blockwork and stonework shall be given in squire
meters or enumerated or may be given in the description.
Holes in timber – Holes for bolts and the like shall each be enumerated separately
stating the size of bolts and the thickness of timber.
Iron-mongery
Particulars of the following shall be given:-
Kind and quality of Iron-mongery
Surface finish
Nature of the background (e.g. timber, metal…) to which items are fixed
49
FIXTURES AND FITTINGS - SECTION M28 Cupboards, Tables, Work-benches, Counters, Bookcase etc., shall be given in detail or
may be enumerated and fully described.
Those of similar character may be grouped together.
Drawers shall be enumerated stating the overall dimensions, the thickness of
component parts and the method of joining.
Applied covering – In square meters stating the method of securing.
PAINTING AND DECORATIONS – SECTION (U)
Work is grouped into:-
Internal work
External work
Generally, work on surface over 300mm girth shall be given in square meters.
Those not exceeding 300mm girth shall be in linear meters
Those not exceeding 0.10 square meter shall be enumerated
Particulars of the following shall be given
1. Kind and quality of material
2. Nature of work (e.g. lime whiting, painting, varnishing)
3. Nature of base on which work is executed
4. Preparatory work- (rubbing down, repairing cracks, scrubbing)
5. Number of priming or sealing coats
6. Number of undercoat
7. Number of finishing coat
50
Measured on groups according to the nature of the background such as:-
On general surfaces
On wood, frames, wood windows and glazed wood doors
On metal windows and glazed metal doors
On structural steelwork
On grilles, balustrades, railing and mesh
On gutters
On pipes
On bars, cables, conduits, straps and ducting
51
BILLS OF QUANTITIES
Bills of quantities is a fully described and accurately representation of the works to be
executed. Bills of quantities consist of preliminaries, prime cost sums, provisional sums
and measured works.
Purposes of bill of quantities
(a) It enables all contractors tendering for a job to price on exactly the same
information with a minimum effort. In the absence of a bill of quantities being
prepared by the building owner each contractor would have to preparing his own
Bill of Quantities in the limited amount of time allowed for tendering. These
places a heavy burden on each contractor and also involve him, in additional
costs.
(b) It provides a basis for the valuation of variations which often occur during the
progress of the work.
(c) It gives an itemized list of the component parts of the building, with a full
description and the quantity of each part, and this may assist the successful
contractor in ordering materials and assessing his labour requirements for the
job.
(d) After being priced, it provides a good basic for “cost planning and cost analysis
work”.
Forms of Bills of Quantities
Elemental bills
In Elemental bills, items are grouped according to their position in the building. Each
element comprises an integral part of the building such as external walls, roofs or
floors, which each perform a certain design of function. Within each element, the items,
may be billed in trade order or grouped in building sequence.
52
Trade bills
In Trade bills, items are arranged in trade order under the main headings of the
separate trades.
Sectionalized Trades bills
This can be presented either as a trade bill or with elements as the main subdivision.
Operational bills
The description of the billed work follows the actual building process, with materials
shown separately from labour, all described in terms of the operations necessary for
the construction of the building. An operation for the purpose of the operational bill is
the work performed by a man or gang between definite breaks in the pattern, such as
bricklaying from damp-proof course to first floor joists in housing work.
BILL PREPARATION PROCESSES
Working – up
After the „taking - off‟ the quantities, squaring the dimensions and entering the resultant
lengths, areas and volumes in the third or squaring column on the dimension paper
follows. The next stage is transferring the squared dimensions to the abstract or
transferring the items directly from the dimension sheet to the bill. In the bill of
quantities, the various items of work making up the job are listed under the appropriate
trade or section headings, with descriptions printed in full and quantities given in
recognized units of measurement as per SMM. The above narrated process is known
as „working – up‟.
53
Ruling of Bill of Quantities
1
2
3
4
5
6
Column No. Use of column
1 Item
2 Description
3 Quantity
4 Unit
5 Rate
6 Amount
Item
Description
Quantity
Unit
Rate
Amount
A B C D E
SUBSTRUCTURE
Vegetable soil
Excavation of vegetable. soil, average150mm deep and deposit. on site in spoil heaps, average. 20 metres away from excavations
Trees and Hedges Cutting down small trees n.e 600mm girth and grubbing up their roots
Cutting down Michongoma hedges and grubbing up their roots. ……………………. ………………………..
20
10
15
M2
NO M
20,000 3000 1500
400,000 30,000 22,500
TO COLLECTION
Pg. 8/3/1/1
54
Item
Description
Quantity
Unit
Rate
Amount
A B C D E
ELEMENT NO 1: SUBSTRUCTURE
Trench excavation and Disposal
Excavation of foundation trenches.. not exceeing 1.5 meter deep starting at stripped levels. Backfill excavation materials around foundation
…………………….. ……………………. Concrete bed 100mm Thick concrete bed (1:2:4) mix
ratio 20) aggregate.
20
5 30
M3
M3
M2
………
…….
…………
………… ………… ………….
TO COLLECTION
COLLECTION
Pg. 8/3/1/1 xxxxxx
Pg. 8/3/1/2 xxxYYY
TOTAL COLLECTION ELEMENT NO.1 CARRIED
TO SUMMARY
YXYXY
Pg. 8/3/1/2
55
Item
Description
Quantity
Unit
Rate
Amount
A B C D E
ELEMENT NO 2: ROOFING
Roof structure
………………………………… …………………………………
…………………….. …………………….
Roof coverings ……………………………….
…
…..
…. …
M
M
M2
………
……
…..
……….
………. ……….. ……….. ………..
TOTAL ELEMENT NO 2 CARRIED TO SUMMARY
…………
Pg. 8/3/2/1
Units of Measurement
The commonly used in the Bills of Quantities are Linear, Square and cubic respectively
They are abbreviated as M, M2, M3, Kg, Prs
Entering Quantities in the Bill
Quantities are to be billed to the nearest whole unit. Fractions of units which are
less than one – half are. Disregarded
When the above application causes an entire item to be eliminated, the item is to
be enumerated stating the size or weight.
56
General Rule of Billing
Items will be grouped under suitable section and sub-section headings and will
follow the order and terms adopted in the SMM.
The preamble clauses will be inserted at the head of each section
Each item to be priced in the bill is indexed by letters and or numbers in the first
column
Words in the bill will written in full without any abbreviation
Provision is made for the total sum on each page of the bill relating to a given
section of work to be transferred to a collection at the end of the section
The total of each of the collections is transferred to a summary at the end of the
bill
Note: On completion of the draft bill must be very carefully checked against the
abstract or the squared items and those items suitably marked in colored
ink or pencil as each item is dealt with.
Numbering the BOQ Pages
The bidding document is divided in various sections such as:-
Section 1 - Invitation to Tender
Section 2 - Instruction to Tenderers
Section 3 - Tender Data Sheet
Section 4 -General conditions of contract
Etc. etc
Numbering of the pages in the Bill of Quantities follows the sequence of section; bill
No., Element No and the page No.
For example the page below indicate that, fencing work is placed at section number 9,
it is in bill number 3, Element No. 1 on page 1.
Here below is an example of the Bill of Quantities