ELEMENTS OF QUANTITY SURVEYING UPDATED.pdf

SCHOOL OF ENGINEERING-NYARUGENGE CAMPUS
CEGE DEPARTMENT
Program: CIVIL ENGINEERING
Year III
CIV 3162 ELEMENTS OF QUANTITY SURVEYING Revised Lecture notes
Revised by :
EngMunderereEgide
Eng. FulgenceNtihemuka
Revision Date: November,2019
COLLEGE OF SCIENCE AND TECHNOLOGY

Course Arrangement

Notes: Power Points & Some References

Assessment: 2 CATs,
2 Assignments,
2 Quizzes
1 two hour exam
Teaching

For each week of term, this course is taught as follows: See schedule online

Course grades
We assess your performance on this module as follows:

Quizzes: 10%

Assignment: 20%

CAT’s: 20%

A 2-hour Final exam -50% of the marks.

COURSE CONTENTS
I.Introduction to Estimating and Costing
II. Measurement of Materials and Works.
III. Types of Estimates
IV. Detail & Abstract Estimates of Building
and water structures.
V. Analysis of Rates
VI.Valuation
VII. Earthwork Calculations

COURSE CONTENTS
VIII. Hexagonal Rooms
IX. Estimation Of Excavation Of Farm Pond
X. Estimate of a Building with Jack Arch and
Arch Openings
XI. Septic Tanks
XII. Reinforcement Detailing

Unit 1. Introduction to Estimating and
Costing
Definition
Need for estimating and costing
Procedure of estimating and costing
Data required to prepare an estimate
Complete estimate
Lump sum
Work charged establishment

Unit 1. Introduction to Estimating and
Costing
Definition of Estimating and Costing
Estimating and Costing is the technique of calculating or
computing the various quantities and the expected cost on
a particular project.
In case it is realised that the funds available are less than
the expected cost, an appropriate decision is taken: ( For
example the work may be done in part by reducing it or
specifications are altered).
An estimate is an assessment of the probable total cost of
some future activity.

Unit 1. Introduction to Estimating and
Costing
Definition of Estimating and Costing
There are three main requirements necessary for preparing
an estimate.
1)Drawings like Plan, Elevations and Sections of important
points.
2)Detailed specifications about workmanship & properties
of materials
3)Standard schedule of rates of the current year

Unit 1. Introduction to Estimating and Costing
Purpose of estimation

To assess the volume of work involved in the
project.

To arrange and organize material, manpower,
equipment and tools-and-plant necessary for the
project.

To fix the project completion period.

To ascertain the fund required for completing the
purpose to work.

Unit 1. Introduction to Estimating and
Costing
Purpose of estimation (Concluded)

To justify the investment from cost benefit
ratio.

To invite tenders and preparation of bill of
quantities.

To obtain necessary administrative approval,
necessary technical sanction and arrangement
and allocation of funds required for the project.

For valuation of an existing property.

Unit 1. Introduction to Estimating and Costing
Quantity Surveyor

Quantitysurveyorisapersonwhoisresponsibleon
estimatingthequantitiesfromthedesigndrawings,and
measurementofthequantitiesinthesiteduringthe
projectimplementation,andpreparingthecurrentand
finalpayments.

Unit 1. Introduction to Estimating and
Costing
Duties of quantity surveyor:

Preparing bill of quantities (Taking off, squaring,
Abstracting and billing)

Preparing bills for part payments at intervals
during the execution of work.

Preparing bill of adjustment in the case of variations
ordered during the execution of work

Giving legal advice in case of court proceedings

Unit 1. Introduction to Estimating and Costing
Essentialqualitiesofagoodsurveyor

Thequantitysurveyormustbewellversedwiththe
drawingsofwork.

Heshouldbeabletoreadthedrawingcorrectlyand
billthequantitiesaccurately

Heshouldhaveathoroughknowledgeofthe
constructionproceduretobeadopted,thevarious
itemsofworksinvolvedintheexecution:andthe
differentmaterialstobeusedinthework.

Heshouldbeabletopreparescheduletobepricedby
tender.

Unit 1. Introduction to Estimating and Costing

Before preparing the estimate, the estimator should visit
the site and make a study of conditions. 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 Project.
Get all data available regarding the soil.
Make a sketch of the site showing all important
details.
Obtain information concerning light, power, and
water

Unit 1. Introduction to Estimating and Costing
Secure information concerning banking facilities.
Investigate general efficiency of local workman.

Unit 1. Introduction to Estimating and
Costing
Procedure of Estimating
Estimating involves the following operations:
1)Preparing detailed estimate.
2)Calculating the rate of each unit of work
3)Preparing abstract of estimate

Unit 1. Introduction to Estimating and
Costing
Data Required to Prepare an Estimate
DRAWINGS
SPECIFICATIONS

Unit 1. Introduction to Estimating and
Costing
Data Required to Prepare an Estimate
RATES
In order to be able to prepare the estimate of a project,
the unit rate of each item of work is required.
For arriving at the unit rate of each item we need:
1)The rate of various materials to be used in the
construction
2)The cost of transport of materials
3)The wages of labour, skilled or unskilled masons,
carpenters, etc.

Unit 1. Introduction to Estimating and Costing
Complete Estimate
Most of people think that the estimate of a structure includes
cost of land, cost of materials and labour but many other
direct and indirect costs are included as shown below.

Unit 1. Introduction to Estimating and
Costing
LUMPSUM

Unit 1. Introduction to Estimating and
Costing
Terminology
Taking off in quantity surveying:
Thisistheprocessoffindingoutthequantitiesfor
variousitemsofworksinvolvedinaprojectby
takingoffvariousdimensionsfromtheplan,
sectionsofthedrawingsandtabulatingina
measurementseat.Themeasurementsheet
containsfollowingcolumnslikedescription,
number,length,breadth,thickness/heightand
quantity.

Unit 1. Introduction to Estimating and
Costing

Contingencies:
There are certain expenses which are incidental in
nature and it is not possible to predict them with
reasonable accuracy. To cater all such expenses,
an additional amount of 3% to 5% of estimated
cost is provided in the total estimate.

Unit 1. Introduction to Estimating and Costing

Lump sum items:
Thesearesmallitems,suchas,frontarchitecturalor
decorationworkofabuilding,fireplace,site-cleaning
anddressing,etc.,forwhichdetailedquantities
cannotbetakenouteasilyorittakessufficienttime
tofindthedetails.Forsuchitemsalump-sumrateis
providedintheestimate.

Unit 1. Introduction to Estimating and
Costing

Work charged establishment:
Duringtheconstructionofaprojectconsiderable
numberofskilledsupervisors,workassistance,
watchmenetc.,areemployedontemporarybasis.
ThesalariesofthesepersonsaredrawnfromtheL.S.
amountallottedtowardstheworkcharged
establishment.Thatis,establishmentwhichis
chargeddirectlytowork.AnL.S.amountof1½to
2%oftheestimatedcostisprovidedtowardsthe
workchargedestablishment.

Unit 1. Introduction to Estimating and Costing

Day work:
Duringexecutionofaprojecttheremaybecertaintypeof
works,forwhichtheactualquantitiesoflaborrequiredis
difficulttomeasure.Forexamplefinearchitecturalworks,
anddrawingsinthewall.Thepaymentstowardssuch
itemsaremadeonthebasisofactualnumberofdaysor
actualquantityofmaterialsrequired.Suchworksare
knownasdayworks.

Unit 1. Introduction to Estimating and
Costing
Provisional quantities:

Duringpreparationofanestimateifitis
apprehendedthatadditionalquantitiesagainstsome
itemsmayberequiredduetovariationofsite
conditions,thenthosequantitiesareestimated
separatelyfromthedimensionsofthedrawingsand
keptseparatelyintheestimateunderaheading
ProvisionalQuantities.

Unit 1. Introduction to Estimating and
Costing

Sub work:
Alargeprojectmayconsistofseveralindependent
smallworks.Suchsmallworksareknownassub
work.Forexamplesettingofauniversitymay
containtheconstructionofadministrativebuilding,
classrooms,facultychambers,hostelsandfaculty
residences.Estimationsforeachofthesubworksare
doneseparatelyandaccountsofexpenditurearekept
subworkwise.

Unit 1. Introduction to Estimating and Costing

Provisional sum:
Whilepreparingtheestimatesomeamountisprovided
initforitemswhosedetailsregardingcostor
specificationsareunknownduringthepreparation.
Forexamplethecostandspecificationsforaliftmay
beunknownduringestimationforthebuilding.Such
amountsareknownasprovisionalsum.Howeverthe
paymentsfortheseprovisionalitemsaredoneasper
actualrate.

Unit 1. Introduction to Estimating and Costing
Work value:
Thisisthetotalamountprovidedforallscheduled
itemsofworkintheestimate.Thusworkvalueisthe
estimatedvaluefortheworkexcludingtheamount
forcontingencies,workchargedestablishment,tools
andplantsetc.asperactualrate.

Unit 1. Introduction to Estimating and Costing
Summaryofestimatedcost:
Thisisthesummationofabstractofestimatedcosts
fordifferentsub-worksinvolvedintheprojectandis
drawnupseparately.Suchasummarypageis
preparedwhenaprojectcontainsdifferentsub-
works.

Unit 1. Introduction to Estimating and
Costing

General abstract of cost:
Thisisthesummarizationofabstractofcostsof
severalindividualitemsofsub-worksorworksasa
whole,like:costofland,earthwork,bridges,
pavement,retainingwall,etc.requiredtocompletea
roadproject.Theamountrequiredforcontingency,
T&P,workchargedestablishment,maintenanceetc
areaddedonpercentagebasistothegeneralabstract
ofacost.

Unit 1. Introduction to Estimating and
Costing

Billofquantities(BOQ):Thisisdefinedasalistofbrief
descriptionsandestimatedquantities.Thislistsinatabular
formalltheitemsofworkinvolvedinconnectionwith
estimateforaprojectwiththedescription,corresponding
quantity,unitrateandamountscolumn.Thecolumns
indicatingunitrateandamountsarekeptblank.BOQis
providedinatenderformforitemratetenders.
Contractors’putuptheirowncompetitiveratesand
calculatethetotalstooffertheirestimateamountto
completethewholework.TheBOQisalsorequiredto
calculatethequantitiesofdifferentmaterialsrequiredfor
theproject

Unit 1. Introduction to Estimating and
Costing

Tools and plants (T&P):
Useofspecialtypeoftoolsandplants,likeconcrete
mixture,batchingplantsplant,etc.,mayberequired
forefficientexecutionoflargeprojects.Tocatersuch
expensesabout1%to1.5%oftheestimatedcostis
allottedundertheheadtoolsandplants(T&P).

Unit 2. Measurement of Materials & Works
Units of Measurement
Rules for Measurement
Method of taking out quantities
Long Wall-Short Wall Method
Center Line Method
Partly center line and partly cross wall
method

Unit 2. Measurement of Materials & Works
Units of Measurement
There exist various system of units of measurement.
Metric system of units is the most preferable. This is
due to its simplicity as the units are multiple of ten or
one-tenth of other.
For Engineering works the units which are commonly
used are Metre for length, Square metre for area,
Cubic metre for volume, kilogramfor mass and
litrefor capacity.

Unit 2. Measurement of Materials & Works
Units of Measurement
Principle of units for various items of
works
The units of different works depend on their
nature, size and shape. In general, the units of
different work are based on the following
principle:

Unit 2. Measurement of Materials & Works
Units of Measurement
N.B: Units of measurement and payments of various work are
same in metric units system except for earthworks which are
sometimes paid per 100 cum (per % cum).
a)Single units work like doors, windows, trusses etc., are
expressed in numbers.
b) Works consisting of linear measurements involve length
like : fencing, hand rail, are expressed in running metres
(RM)
c) Works consisting of areal surface measurements involve
area like plastering, white washing, partitions of specified
thickness etc., are expressed in square meters (m²)
d) Works consisting of cubical contents which involve volume
like earth work, cement concrete, Masonry etc. are expressed
in Cubic metres(m
3
).

Unit 2. Measurement of Materials & Works
Units of Measurement and payment for various items of works
and materials

Unit 2. Measurement of Materials & Works
Rules for Measurement

The rules for measurement of each item are invariably described .However some of
the general rules are listed below.

Unit 2. Measurement of Materials & Works
Rules for Measurement

Unit 2. Measurement of Materials & Works
Any
Question ?

Unit 2. Measurement of Materials &
Works
SITE CONDITIONS AFFECTING THE OVERALL
COST
Qualityoflabourandlabouroutputvariesindifferent
localities.
Weatherconditionsgreatlyaffecttheoutputand,hence,
theoverallcost.
Groundconditionsvaryandchangethemethodof
construction.Forexample,excavationmaybedry,wet,
hard,soft,shallowordeeprequiringdifferentefforts.

Unit 2. Measurement of Materials &
Works
Thesourceofavailabilityofasufficientsupply
ofmaterialsofgoodqualityisalsoafactor.
Theavailabilityofconstructionmachineryalso
affectsthemethodofconstruction.
Accesstothesitemustbereasonable.Ifthe
accessispoor,temporaryroadsmaybe
constructed.

Unit 3. TYPES OF ESTIMATES

There are two main types of estimates:-
1 . Rough cost estimate/Preliminary
Estimate/Approximate.
2 . Detailed estimate.

Depending upon the purpose of estimate, some
types of detailed estimate are as follows:
a)Contractor's estimate
b)Engineer's estimate
c)Progress estimate

Unit 3. TYPES OF ESTIMATES
1 . Rough cost estimate
o
Tofindroughcostofanyproject,thisworkedaverage
unitcostismultipliedwithtotalquantityofthepresent
workinthesameunits.
o
Forexample,incaseofabuilding,plintharea(sq.m.)
oftheproposedbuildingisworkedout,whichisthen
multipliedbythecostperunitarea(Rwf./m
2
)ofsimilar
buildingactuallyconstructedinthenearpastinnearly
thesamesiteconditions,tofindouttheroughcost
estimateofthebuilding.

Unit 3. TYPES OF ESTIMATES

ApproximateEstimate
ApproximateEstimateismadetofindoutan
approximatecostinashorttimeandthusenable
theadministrativeauthoritiestoevaluatethe
financialaspectsofvariousschemesand
subsequentlyallowsthemtosanctionthem.

Unit 3. TYPES OF ESTIMATES

Importance
Approximateestimateispreparedwithpreliminary
investigationandsurvey.Itdoesnotrequiredetailed
surveyingdesign,drawingetc.Itisbasicallydoneto
evaluatefeasibilityofaproject.Ifitisobservedfrom
approximateestimatethatthecostoftheprojectis
veryhighthentheprojectmaybeabandoned
withoutpreparingadetailedestimate.Thusthecost
requiredfordetailedsurveyingdesignordrawing
requiredforpreparationofdetailedestimateis
saved.

Unit 3. TYPES OF ESTIMATES
Purpose of approximate estimate

Approximateestimateprovidesanideaaboutthe
costoftheproject,whichenablestheauthorityto
checkthefeasibilityoftheprojectsconsideringthe
fundsavailablefortheproject.

Approximateestimatedoesnotrequireanydetail
investigation,designordrawingandhencesaves
bothtimeandmoney.

Unit 3. TYPES OF ESTIMATES

Ifseveralalternativesareavailablefortheoriginal
works,acomparisonisdonefromapproximate
estimateandthedecisionismadetoselectthe
projectaccordingtothiscomparison.

Unit 3. TYPES OF ESTIMATES

Approximateestimateisrequiredforgettingthe
administrativeapprovalforconductingdetailed
investigation,designandestimation.

Approximateestimateforapropertyorprojectis
requiredforinsurancesandtaxscheduling.

Unit 3. TYPES OF ESTIMATES

The rough cost estimate may be prepared on the following basis
for different types of projects:
1. Cost per square meter of covered area (plinth area) is
the most commonly adopted criterion for preparing rough cost
estimate for most of the residential buildings.
2. For public buildings, cost. Per person (cost per capita) is
used. For example,
Students hostel———————-—cost per student
Hospitals————————————Cost per bed
Hotel—————————————Cost per Guest

Unit 3. TYPES OF ESTIMATES
Approximate Estimate

Unit 3. TYPES OF ESTIMATES
Approximate estimate-Example for a plinth area method
Prepare an approximate estimate of building project with total plinth
area of all building as 1000 m
2
and from the following data:
a)Plinth area rate 100000 Frw per m
2
b)Cost of water supply is 7.5% of the cost of building
c)Cost of sanitary and electrical installations is 7.5% of the cost of
building
d)Cost of architectural features is 1% of building cost
e)Contingencies is 4% of building cost
Determine the total cost of building project

Unit 3. TYPES OF ESTIMATES
Approximate estimate-Example for a plinth area method
SOLUTION
Plinth Area= 1000m
2
Plinth Area rate = 100000 Frw/m
2
Total Structural cost of the building= 1000*100000= 100 000 000Frw
Additional Costs
Cost of water supply charges = 100 000 000*0.075= 7500 000Frw
Cost sanitary and electrical installation = 100 000 000*0.075= 7500 000Frw
Cost of architectural features = 100 000 000*0.01= 1 000 000 Frw
Cost for contingencies = 100 000 000*0.04 = 4 000 000Frw
Cost of supervision = 100 000 000 * 0.05 = 5 000 000 Frw
Grand Total for the building = 125 000 000 Frw

Unit 3. TYPES OF ESTIMATES
Approximate estimate-Example for Cubical Contents method
A water distribution institution wants to construct an apartment for its
employees. The proposed apartment is 40*50m (outer dimensions).
Determiner the approximate total cost of the apartment by cubical
contents method based on the following data.
a)Rate of construction = 10 000 Frw per m
3
b)The height of apartment = 16.25m
c)Water supply, sanitary and electrical installation each @ 6% of
building cost
d)Architectural appearance = 1% of the building cost
e)Contingencies = 4% of the building cost

Unit 3. TYPES OF ESTIMATES
Approximate estimate-Example for Cubical Contents method

Unit 3. TYPES OF ESTIMATES
Approximate estimate-Example for Unit base method
The district wants to construct a hospital that can hold 250
patients. The cost of construction al together for each bed is
750 000Frw. You are requested to provide a rough or approximate
estimate of the total cost for hospital building.
SOLUTION
No. of beds = 250
Cost of construction per unit = 750 000 Frw
Total Cost of hospital building = 750 000 * 250 = 187 500 000 Frw

Unit 3. TYPES OF ESTIMATES
DETAILED ESTIMATE
•
Detailedestimatesarepreparedbycarefullyand
separatelycalculatingindetailthecostsofvariousitems
oftheworkthatconstitutethewholeprojectfromthe
detailedworkingdrawingsafterthedesignhasbeen
finalized.
•
Detailedestimatesaresubmittedtothecompetent
authoritiesforobtainingtechnicalsanction

Unit 3. TYPES OF ESTIMATES
Thewholeprojectissub-dividedintodifferent
itemsofworkoractivities.Thequantityforeach
itemisthencalculatedseparatelyfromthe
drawingsasaccuratelyaspossible.Theprocedure
isknownas"takingoutofquantities".
Thequantitiesforeachitemmaybeestimatedand
showninthepatternwhichiscalled "Billof
quantities."

Unit 3. TYPES OF ESTIMATES

Unit 3. TYPES OF ESTIMATES
DETAILED ESTIMATE
Eachitemoftheworkisthenmultipliedbyits
estimatedcurrentratecalculatedbyafixed
proceduretofindoutcostoftheitem.
Attheend,atotalofallitemsoftheworkare
madetogetthetotalestimatedcost.
TheratesareusuallyasperScheduleofRates
fortheandmaterialratesoverandabovethe
scheduleofrates
.

Unit 3. TYPES OF ESTIMATES
Besidesdrawingsanddetailsofmeasurementsandcalculationof
quantities(BillofQuantities),thefollowingdocumentsarealso
usuallysubmittedwiththedetailedestimateforobtainingTechnical
Sanction
Specifications lying down the nature and class of work and
material to be used in various parts of the work.
The abstract of cost (priced Bill of Quantities) showing the total
quantities under each sub-head, rate per unit of measurement, and
cost.
Calculation sheets showing calculations for important parts of the
structure. In fact, in estimating the art and skill lies only in the
computation of details without any omissions, of all parts of the
building or work
.

Unit 3. TYPES OF ESTIMATES
1-CONTRACTOR ESTIMATE
It is made by the contractor for determining the price or prices to be
bid. It is usually a carefully prepared detailed estimate2-ENGINEER’S ESTIMATE
ThistypeofestimateismadebytheEngineer(Consultant)usually
forthepurposesoffinancingtheworkandforcheckingbidsand
runningbillssubmittedbycontractors

Unit 3. TYPES OF ESTIMATES
3-PROGRESS ESTIMATES
•
ThesearemadebytheEngineeratregularintervalsfor
thecompletedpartsoftheprojectduringtheprogressof
theworkfordeterminingtheamountsofpartialpayments
tobemadetothecontractor.
•
Onlargecontracts,suchestimatesare
commonlymadeeachmonthand,hence,are
frequentlycalledmonthlyestimates.

Unit 3. TYPES OF ESTIMATES
UNFORESEEN ITEMS IN DETAILED ESTIMATE
•
Whilepreparingadetailedestimate,onehadtobevery
carefultoseethatallitemsoftheworkareincorporated.
•
ItislikelythatafewItems,thoughunimportantinnature,
mighthavebeenoverlookedandwhichmayresultin
raisingtheestimateoftheproject.
•
Theremaybealsocertainunforeseencircumstances
affectingtheproject.

Unit 3. TYPES OF ESTIMATES
•
Hence,acertainallowanceusually5to10%ofthetotal
cost,ismadeintheestimationwhichwilltakecareofall
theseitemsthatareunforeseenorareoverlookedandare
knownas"Contingencies".

Unit 3. TYPES OF ESTIMATES
METHODS OF DETAILED ESTIMATE
Thedimensions,length,breadthandheightordepth
aretobetakenoutfromtheworkingdrawings(plan,
elevationandsection).

Junctionsofwalls,cornersandthemeeting
pointsofwallsrequirespecialattention.For
symmetricalfootings,whichistheusualcase,
earthworkinexcavationinfoundations,
foundationconcrete,brickworkinfoundation
andplinth,andbrickworkinsuperstructuremay
beestimatedbyeitherofthetwomethods:
Unit 3. TYPES OF ESTIMATES
METHODS OF DETAILED ESTIMATE
(1) SEPARATE OR INDIVIDUAL WALL METHOD
(2) CENTER LINE METHOD

Unit 3. TYPES OF ESTIMATES
•
Thewallsrunninginonedirectionaretermedas"long
walls”andthewallsrunninginthetransversedirection,
as"ShortwaLls",
•
Lengthsoflongwallsaremeasuredorfound"Out-to
out"andthoseofshortwallsas"In-to-in".
•
Differentquantitiesarecalculatedbymultiplyingthe
lengthbythebreadthandtheheightofthewall.

Unit 3. TYPES OF ESTIMATES
•Long wall length out-to-out
= Center to center length + half breadth
on one Side + half breadth on other side.
= Center to center length + one
breadth
•
Short wall length in-to-in= Center to Center
length -one breadth.

Unit 3. TYPES OF ESTIMATES
CENTERLINEMETHOD
Inthismethodknownascenterlinemethod
sum-totallengthofcenterlinesofwalls,longand
short,hastobefoundout.
Findthetotallengthofcenterlinesofwallthe
sametype,longandshorthavingthesametypeof
foundationsandfootingsandthen findthe
quantitiesbymultiplyingthetotalcenterlength
byrespectivebreadthandheight.

Unit 3. TYPES OF ESTIMATES
This method is quick but requires special
difference when there are cross walls or number of
junctions at meeting points of partition or cross
walls, etc.
For every junction of partition or cross walls with
main walls, special consideration shall have to be
made to find correct quantity.
For each junction half breadth of the respective
item or footing is to be deducted from total length

Unit 3. TYPES OF ESTIMATES
Inthecentrelinemethod,thesumofallthecentre
linelengthsoflongwallsandshortwallsare
addedtogetthetotalcentrelinelength.

Unit 3. TYPES OF ESTIMATES
Atthejunctionsoftwowalls,thelengthis
presentinbothofthewalls.Hencehalfofthe
lengthofthatwidthistobesubtractedfromthe
totalcentrelinelength
Length=Totalcentrelinelength–½widthx
numberofjunctions

Unit 3. TYPES OF ESTIMATES
Partlycenterlineandpartlycrosswallmethod
Thismethodisadoptedwhenexternal(i.e.,aroundthe
building)wallisofonethicknessandtheinternal
wallshavingdifferentthicknesses.Insuchcases,
centerlinemethodisappliedtoexternalwallsand
longwall-shortwallmethodisusedtointernalwalls.
Thismethodsuitsfordifferentthicknesseswallsand
differentleveloffoundations.Becauseofthisreason,
allEngineeringdepartmentsarepracticingthis
method.

Unit 3. TYPES OF ESTIMATES
Detailed Estimate

Unit 3. TYPES OF ESTIMATES
Factors Affecting the Cost of a Project

Location of Site: If the site is located at an odd
place for which loading, unloading, staking and
restacking of materials are necessary for several
times. Thus, apart from cost incurred by such
operations the possibility of damage or loss in transit
is more which affects the cost.

Labor charges: The skill and daily wage of the
local labor affects the rate of a item.

Unit 3. TYPES OF ESTIMATES
Factors Affecting the Cost of a Project

Quantity of materials: For a large project, the
quantity of materials required is large and thus it can
be procured at a lower price.

Availability of materials: The cost of materials,
which are easily available, is comparatively lower.

Transportation of materials: The cost of
transportation is added to the cost of the material at
site. Thus more is the transportation cost; the more is
the cost of material.

Unit 3. TYPES OF ESTIMATES
Documents Accompanying Detailed Estimate
The detailed estimate is generally accompanied by
following supporting documents:
a. Report on the design
b. Specifications
c. Working drawing (Plans, section, elevation and
other details)
d. Design calculations
e. Particulars of scheduled rates or rate analysis

Main items in building work:
Main items in building work:
S/NParticularsUnitRemarks
1
EarthworkCumEarthwork in excavation and in filling
should be taken out separately under
different types.
Foundation trenches are usually dug
to the exact width of foundation with
vertical sides.
2
Bed concrete in
foundation
CumIt is calculated by taking length, breadth
and thickness of concrete bed.

Unit 3. TYPES OF ESTIMATES
3MasonrycumMasonry for foundation masonry for
superstructure is Deductions for openings like
lintels, doors, windows, cupboards, etc. is done.
Thin partition walls of thickness less than 10 cm,
4R. C. C.
works
R.C.C. Work is calculated for beams,
lintels,
columns, footing, slabs etc. No deduction
for steel is done while calculating the
quantity of concrete
5Reinforc
ement
TonThe reinforcement quantity is taken off
from detail drawing and bar bending
schedule.
.

Unit 3. TYPES OF ESTIMATES
6Floori
ng
Sqm
For grounds floor, cement concrete
and floor finishing of stone, marble
or mosaic tiles taken under one item
and quantity is calculated in square
meter.
7Roof
Cum/
Sqm
In case of roof, flat roofs are calculated
in cubic meter like slab
In case of roofing material tiles, G.I.
sheets or A.C. sheets are measured in
square meter.

Unit 3. TYPES OF ESTIMATES
8Plastering
and pointing
SqmPlastering is expressed with specified
thickness. For masonry the measurements
are taken for whole face of wall for both
sides as solid and deduction for openings
are made.
9Painting,
white
washing and
distempering
Sqm
10Electrificatio
n
LSGenerally 8% of estimated cost of building
works is taken for this item.

Unit 3. TYPES OF ESTIMATES
Example1:(Quantityestimationofasymmetricalwall)
TheplanandcrosssectionofawallisgiveninFig.
Estimatethequantitiesoffollowingitemspermeter
lengthofthewall.
a.Earthworkinexcavationinfoundationtrench
b.Concretebedinfoundation
c.Firstclassbrickworkin1:4mortarmixinfoundationand
plinth
d.1stclassbrickworkinsuperstructurewall
e.2.5cmthickDPC(1:2:4)withwaterproofingcompound

Unit 3. TYPES OF ESTIMATES

Unit 4. DETAIL AND ABSTRACT ESTIMATES
Contents
Typical Example with an Underground Water Tank
Typical Example with a Simple Building

Unit 4. DETAIL AND ABSTRACT ESTIMATES
Typical Example with an Underground Water Tank
An institution in charge of water distribution in Rwanda wants to construct
an underground water tank. As an engineer you are required to carry out a
detail and abstract estimate of the following items in that project based on
the drawings provided below.
a)Earthwork in excavation
b)Cement concrete (1:2:4) in foundation
c)1
st
class brickwork in cement mortar (1:3)
d)2.5 cm thick artificial stone flooring
e)16mm thick cement plaster (1:3) on floor and walls
f)12mm thick cement plaster (1:3) on top of wall and external plastering

Unit 4. DETAIL AND ABSTRACT ESTIMATES
Typical Example with an Underground Water Tank

Unit 4. DETAIL AND ABSTRACT ESTIMATES
Typical Example with an Underground Water Tank
SOLUTION
Centre Line method
Total length of centre line for 40mm thick wall=
(5.4+3.9)*2=18.6m
Total length of centre line for 30mm thick wall=
(5.3+3.8)*2=18.2m
Total length of centre line for 20mm thick wall=
(5.2+3.7)*2=17.8m

Unit 4. DETAIL AND ABSTRACT ESTIMATES
Details of measurements and calculation of quantities
S.No
Description of
item
No
Length
(L) m
Breadt
h (B) m
Height/Dep
th (D) m
Quantit
y
Total
Qt
UnitExplanatory note
1
Earth work in
Excavation 16.14.6 2.775.76275.762m
3
L=5+(0.4*2)+(0.15*2
)
6.1m
B=
3.5+(0.4*2)+(0.15*2)
4.6m
D= 0.2+0.9+1.4+0.7-
0.5
2.7m
2
Cement
Concrete (1:2:4)
in Foundation
16.14.6 0.25.6125.612
m
3
L=5+(0.4*2)+(0.15*2
)
6.1m
B=
3.5+(0.4*2)+(0.15*2)
4.6m
h= 0.2m

Unit 4. DETAIL AND ABSTRACT
ESTIMATES
S.
No
Description of
item
N
o
Len
gth
(L)
m
Brea
dth
(B)
m
Height/
Depth
(D) m
Quan
tity
Total
Qt
Un
it
Explanatory
note
3
1st class brick
work in c.m
(1:3)
40cm wall118.60.40.96.696
16.83
2
m
3
30cm wall 18.20.31.47.644
20cm wall 17.80.20.72.492
4
2.5cm thick
artificial stone
flooring153.5 17.517.5m
2

Unit 4. DETAIL AND ABSTRACT
ESTIMATES
5
16 mm thick
cement plaster
(1:3)on walls
and floor
Walls
Short wall 23.5 2.975
20.8
2568.0
75
m
2
H=300-
2.5=297.5C
m
Long Wall 25 2.975
29.7
5
Floor 153.5 17.5

Unit 4. DETAIL AND ABSTRACT ESTIMATES
Details of measurements and calculation of quantities
6
12mm cement
plaster (1:3) on
top of wall and
external
plastering
On top of walls
Short wall 23.70.2 1.48
12.8
6
m
2
Long Wall 25.20.2 2.08
External
plastering
Short wall 23.9 0.53.9
Long Wall 25.4 0.55.4

Unit 4. DETAIL AND ABSTRACT ESTIMATES
Abstract of Estimates (Under ground water Tank)
S.NoDescription of itemQuantity Unit
Rate
(Rwf)
Per
(Unit)
Amount (Rwf)
1Earth work in Excavation75.762 Cu.M 2850Cu.M 215921.7
2
Cement Concrete (1:2:4) in
Foundation 5.612Cu.M148500Cu.M 833382
3
1st class brick work in c.m
(1:3) 16.832Cu.M65000Cu.M1094080
4
2.5cm thick artificial stone
flooring 17.5S.M33500S.M 586250
5
16 mm thick cement plaster
(1:3)on walls and floor
68.075S.M3450S.M234858.75
6
12mm cement plaster (1:3)
on top of wall and external
plastering 12.86S.M3250S.M 41795
TOTAL (Frw) 3,006,287.45

Unit 4. DETAIL AND ABSTRACT ESTIMATES
Typical Example with Simple Building
The figure below shows the plan of a single room building with
section of foundation wall. Prepare detailed and abstract
estimate of the quantities of:
a)Earth work in excavation in foundation
b)Cement concrete bed in foundation
c)Masonry in foundation and plinth
By using long wall-short wall method

Unit 4. DETAIL AND ABSTRACT ESTIMATES
Typical Example with Simple Building

Unit 4. DETAIL AND ABSTRACT ESTIMATES
Typical Example with a Simple Building
SOLUTION
1.Long Wall –Short Wall Method
Length for long walls for an item= Centre length of long wall +
width of item
Length for short walls for an item= Centre length of short wall –
width of item

Unit 4. DETAIL AND ABSTRACT ESTIMATES
Typical Example with Simple Building-Details of
Measurements and calculation of quantities
S.NoDescription of item No
Length
(L) m
Breadth
(B) m
Height/Depth
(D) m
Quantity UnitExplanatory note
1
Earth work in Excavation in
Foundation
Long Wall 26.20.9 1.314.508Cu.ML=5+0.3+0.9
6.2m
D= 0.8+0.3+0.2
1.3m
Short Wall 23.40.9 1.37.956Cu.ML=4+0.3-0.9
3.4m
D= 0.8+0.3+0.2
1.3m
SUB-TOTAL 22.464Cu.M
2
cement in Concrete Bed in
Foundation
Long Wall 26.20.9 0.22.232Cu.ML=5+0.3+0.9
6.2m
Short Wall 23.40.9 0.21.224Cu.ML=4+0.3-0.9
SUB-TOTAL 3.456Cu.M 3.4m

Unit 4. DETAIL AND ABSTRACT ESTIMATES
Typical Example with Simple Building-Details of
Measurements and calculation of quantities
3
Masonry in Foundation and
Plinth
60cm wall
Long Wall 25.90.6 0.32.124Cu.ML=5+0.3+0.6
5.9m
Short Wall 23.70.6 0.31.332Cu.ML=4+0.3-0.6
3.7m
50cm wall
Long Wall 25.80.5 0.84.64Cu.ML=5+0.3+0.5
5.8m
Short Wall 23.80.5 0.83.04Cu.ML=4+0.3-0.5
3.8m
40cm wall
Long Wall 25.70.4 0.62.736Cu.ML=5+0.3+0.4
5.7m
Short Wall 23.90.4 0.61.872Cu.ML=4+0.3-0.4
3.9m
SUB-TOTAL 15.744Cu.M

Unit 4. DETAIL AND ABSTRACT ESTIMATES
Typical Example with Simple Building-Details of
Measurements and calculation of quantities
2. Centre Line Method
S.NoDescription of item No
Length
(L) m
Breadth
(B) m
Height/Depth
(D) m
Quanti
ty
UnitExplanatory note
1
Earth work in Excavation in
Foundation 119.20.9 1.3 22.464Cu.M
L=((5+0.3)*2)+((4+0.
3)*2)
19.2m
D= 0.8+0.3+0.2
1.3m
2
Lime Concrete Bed in
Foundation 119.20.9 0.2 3.456Cu.M
3
Masonry in Foundation and
Plinth
60cm wall 119.20.6 0.33.456Cu.M
50cm wall 119.20.5 0.87.68Cu.M
40cm wall 119.20.4 0.64.608Cu.M
SUB-TOTAL 15.744Cu.M

Unit 4. DETAIL AND ABSTRACT ESTIMATES
Typical Example with Simple Building-Abstracts of
Estimates
S.NoDescription of item Quantity UnitRate
Per
(Unit)
Amount
1Earth work in Excavation in Foundation22.464Cu.M 2850 64022.4
2Cement Concrete Bed in Foundation
3.456Cu.M139500 482112
3Masonry in Foundation Plinth
15.744Cu.M65000 1023360
TOTAL (Frw)
1,569,494.40

Unit 4. DETAIL AND ABSTRACT
ESTIMATES

Exampleonlongwall-shortwallmethod
Estimatethequantitiesoffollowingitemsofatwo
roomedbuildinggiveninFig2.2.
a.Earthworkinexcavationinfoundationtrench
b.concreteinfoundation
c.Firstclassbrickworkin1:6cementmortarin
foundationandplinth
d.2.5cmthickDPC(1:2:4)withwaterproofing
compound
e.1stclassbrickworkincementmortarsuperstructure

Unit 4. DETAIL AND ABSTRACT
ESTIMATES

Unit 4. DETAIL AND ABSTRACT
ESTIMATES

The dimensions of doors, windows and selves are

Door D = 1.20 m ×2.10 m.

Windows W = 1.00 m ×1.50 m

Shelves S = 1.00 m ×1.50 m

Answer: Given in next page

Unit 4. DETAIL AND ABSTRACT
ESTIMATES

Unit 4. DETAIL AND ABSTRACT
ESTIMATES
Exampleoncenterlinemethod
Estimatethequantitiesoffollowingitemsofatwo
roomedbuildinggiveninFig2.3.
a.Earthworkinexcavationinfoundationtrench
b.Limeconcreteinfoundation
c.Firstclassbrickworkin1:6cementmortarin
foundationandplinth
d.2.5cmthickDPC(1:2:4)withwaterproofing
compound
e.1stclassbrickworkincementmortarsuperstructure

Unit 4. DETAIL AND ABSTRACT
ESTIMATES

Unit 4. DETAIL AND ABSTRACT
ESTIMATES

The dimensions of doors, windows and shelves
are

Door D = 1.20 m ×2.10 m.

Windows W = 1.00 m ×1.50 m

Shelves S = 1.00 m ×1.50 m
Ans:

Total center length of the wall = 2 ×c/c of long
wall + 3 ×c/c of short wall
= 2 ×10.60 m + 3 ×6.30 m = 40.10 m

Unit 4. DETAIL AND ABSTRACT
ESTIMATES

Itmaybenotedthat,theabovelengthincludes
someoverlappedportionsatthejointsandthese
excessquantitiesshallhavetobededucted.This
isaccomplishedbyreducingthecenterlength
byhalfbreadthforeachjunction.Thesame
principleappliestofoundationconcrete,to
footings,plinthwallandsuperstructurewall.

Unit 4. DETAIL AND ABSTRACT
ESTIMATES

UNIT 5: SPECIFICATION
Definition:
o
Itdescribesthenatureandtheclassof
thework,materialstobeusedinthe
work,theworkmanshipandthetools
andplantswhicharerequiredto
completeanengineeringprojectin
accordancewithitsdrawingsand
details.
o
Specificationsarewrittenbyexpertsofa
particularfield.

UNIT 5: SPECIFICATION
How to Write Specification
While writing specifications following
principles shall be adopted

Descriptionofmaterials:
Thequalityandsizeofmaterialsrequiredto
doanitemofworkshallbefullydescribed.
Theproportionofmixingortreatmentof
materialsifrequiredbeforeuseshallbe
reallydescribed

UNIT 5: SPECIFICATION

Workmanship:
Thecompletedescriptionofworkmanship.
Themethodofmixingandproportion,
themethodoflaying,,compaction,finishing
andcuringetc.especiallyapplicabletothe
itemofworkshallbestatedindifferent
clause.

UNIT 5: SPECIFICATION
ToolsandPlant(T&P):

Thetoolsandplanttobeengagedtocarryoutawork
shallbedescribed.

Themethodofoperationandbywhomtobesupplied
shallbestated.
ProtectionofNewWork: Themethodof
protectionofnewworksagainstdamageorthe
methodofcuringifrequired,thetestofcompleted
workifnecessaryshallbedescribedinseparate
clauses.

UNIT 5: SPECIFICATION

GeneralSpecificationofBuilding
1.Foundationandplinth: Foundationandplinth
shallbeoffirstclassbrickworkin1:6cement
mortarover1:4:8cementconcrete.
2.Dampproofcourse: DPCshallbeof25mm
thickcementconcrete(1:1.5:3),mixedwithonekg
ofImpermo(oranywaterproofingmaterial)per
bagofcement.

UNIT 5: SPECIFICATION
3.
Superstructure: Superstructure shall be
of 1st class brickwork with 1:6 cement
mortar. Lintels over doors and windows
shall be of R.C.C.
4. Roofing: Roof shall be of 100 mm thick
R.C.C. (1:2:4) slab. Height of the room shall
not be less than 3.5 m.
5. Flooring: type flooring shall be provided
in all floors including staircase.

UNIT 5: SPECIFICATION
6. Finishing: Inside and outside wall shall be
finished with 12 mm cement mortar plaster (1:6).
7. Miscellaneous: Rain water pipe shall be of cast
iron. Building shall be provided with 1st class
sanitary, water fittings and electrical installations.

UNIT 5: SPECIFICATION
DETAILED SPECIFICATIONS OF CIVIL
ENGINEERING MATERIALS
Detailed specification for first class
brick

Theearthusedformoldingthebricksshall
befreefromorganicmatterssaltsand
chemicals.

Thesize,weightandcolouroftheburnt
bricksshouldbeuniform

UNIT 5: SPECIFICATION

Thebricksshallbefreefromcracks,Theyshouldnot
breakwheredropped,from1meterheight,onthe
ground.

The average compressive strength of the bricks shall
be not less than 7.5 N/mm2.

UNIT 5: SPECIFICATION
Detailed Specification for cement

OrdinaryPortlandcementorrapidhardening
PortlandcementconfirmingtoIS:269–1989and
IS:8041–1990shallbeused.

Theaveragecompressivestrength,after7days
curing,of1:3cementmortarcubesshallbenotless
than33N/mm2(33grade).

UNIT 5: SPECIFICATION

DetailedSpecificationforsandformortar
Thesandusedformortarshallbeclean,Itshould
befreefromclay,salt,andorganicimpurities.It
shallnotcontainharmfulchemicalsinanyform.
Mediumandfinesandaretobeusedinmortars.

UNIT 5: SPECIFICATION

Detailed Specification for coarse
aggregate
Theaggregatetobeusedinreinforced
cementconcreteshallbeof,machine
crushedandwellgradedwithanominal
sizeof20mm.Itshallbehard,dense,
durablestrong.Theaggregateshallnot
containharmfulmaterialssuchascoal,clay,
organicimpuritiesetc
.

UNIT 5: SPECIFICATION

Detailed Specification for water for concrete

Waterusedformixingandcuringconcreteshall
becleanandfreefrom,ofoils,acids,alkalis,
salts,sugar,organicmaterialsorothersubstances
thatmaybe,deleterioustoconcreteorsteel.
Potablewatermaybeusedformixingconcrete.
ThepHvalueofwatershallbenotlessthan6.

UNIT 5: SPECIFICATION

Detailed Specification for reinforcement
Thereinforcementshallbeofhighstrengthdeformed
steelbarsconfirmingtoIS:1786–1985.Itshouldbe
bendable,wieldable.Theyieldstrengthofthesteel
usedshallnotbelessthan415N/mm2.

UNIT 5: SPECIFICATION
DETAILED SPECIFICATIONS OF COMMON
CONSTRUCTION WORKSSequence:Levelingthesurface;
Dimensions;Shoring;Fencing;Dumping
thesoil;Waterinfoundation;Treatmentof
thebottom;Trenchfilling;Measurement

UNIT 5: SPECIFICATION
1.Levelingthesurface
Thewholeareaofconstructionistobeclearedoftees,
grass,rootsoftreesetc.,completeandleveled
horizontallytoenableeasymarkingofcentrelineofthe
building
2. Dimensions
The excavation shall be done in accordance with
dimensions of trenches shown in the working
drawings.

UNIT 5: SPECIFICATION
3. ShoringThesidesofthetrenchesshouldbe
verticalandthebottomofthetrenches
shouldbeflat.

UNIT 5: SPECIFICATION
4
.Fencing
Suitabletemporaryfencingistobeprovided
aroundthesiteofexcavationtoavoidany
accidentalfallintothetrenches
5.Dumpingthesoil
Theexcavatedsoilistobedumpedandheap
ataminimumdistanceof1.5metreaway
fromthetrenchessothatitdoesnotslide
againintothetrenches.

UNIT 5: SPECIFICATION
6
. Water in Foundation
Water,ifanyaccumulatedinthetrench,should
bepumpedoutwithoutanyextrapaymentand
necessaryprecautionshallbetakentoprevent
surfacewatertoenterintothetrench.
7. Treatment of the bottom
Thebottomofthetrenchshallbewateredand
compactedbeforethefoundationconcreteis
laid.plainconcretemaybeusedforthe
adjustmentoflevels,thattoowithproper
compaction.

UNIT 5: SPECIFICATION

DETAILED SPECIFICATION OF STONE MASONRY
IN FOUNDATION AND BASEMENT
1. Materials
Thestoneshallbeobtainedfromtheapproved
queries.Itshallbesound,freefromcracksand
decay.[Includedetailspecificationforcementand
sand]

UNIT 5: SPECIFICATION
2. Preparation of mortar
Thematerials(cementandsand),withratio1:6,shall
befirstmixeddrythoroughlytilluniformcolouris
obtainedandthenshallbemixedwetaddingwater
slowlyandgraduallyforatleastturningthreetimes
togiveuniformconsistency.
3. Curing
The masonry should be kept in we condition by
sprinkling water thrice daily for atleast 7 days after
construction.

UNIT 5: SPECIFICATION

DETAILED SPECIFICATION FOR 1ST CLASS
BRICKWORK IN SUPER STRUCTURE
1. Materials
[Include detail specification for first class brick,
cement, and sand].
2. Preparation of mortar
the ratio of cement to sand is 1:4 or as specified.]

UNIT 5: SPECIFICATION
Soakingofbricks
Bricksshallbewellsoakedinwaterforatleast12
hoursbeforetheiruse,preferablyinatankprovided
atsiteofwork.

UNIT 5: SPECIFICATION
Methodoflaying

Bricksshallbewellbondedandlaidin
Englishbondunlessspecified.Everycourse

shallbetrulyhorizontalandshallbetrulyin
plumb.Brokenbricksshallnotbeused

bondingandshallnotexceed 10mmin
thickness.Onlyskilledmasonsshall
beemployedonthework.

UNIT 5: SPECIFICATION

Curing
The work shall be kept well watered for at
least 15 days.

Scaffolding
Necessary and suitable scaffolding shall be
provided to facilitate the construction of
brickwork. It shall be sound and strong
enough to sustain all loads likely to come
upon them.

UNIT 5: SPECIFICATION
DETAILED SPECIFICATION FOR REINFORCED
CEMENT CONCRETE
Proportioning

Proportionsofcement,sandandcourseaggregate
shallbe1:2:4forslab,beamandlintelsand
1:1.5:3forcolumnsunlessotherwisespecified.
TheCement,sandandcourseaggregateshallbe
measuredbyvolumewithboxes.

UNIT 5: SPECIFICATION

Mixingofconcrete

Concreteshallbemixedbyconcrete
mixture.Cement,sandandcourseaggregate
shallbeputintotheconcretemixerasper
therequiredproportionsforonebatch.The
totalquantityshallnotexceedthe
manufacturesratedcapacity.

UNIT 5: SPECIFICATION

Curing of concrete
Freshlylaidconcreteshallbeprotectedfromrainby
suitablecovering.After24hrsoflayingofconcrete
thesurfaceshallbecuredbyflowingwithwaterof
above25mmdepthorwithcoveringbywetgunny
bags.
Thecuringshallbeforaminimumperiodof28days
orotherwisespecified.

UNIT 5: SPECIFICATION

Removal of form work
The centering and shuttering shall be removed after 28
days of casting. It shall be removed slowly and
carefully so that no part is disturbed.

UNIT 5: SPECIFICATION
Detailed specification of for plastering
with cement mortar

Preparation of mortar:
The ratio of cement to sand is 1:4 for inner
wall and 1: 4 for outer wall or as specified.

Curing:
The work shall be kept well watered for at
least 15 days.

UNIT 5: SPECIFICATION
DETAILED SPECIFICATION FOR CEMENT
CONCRETE FLOORING
Bottom LayerThe base shall be of cement concrete of 1:2:4 mix,
25 mm thick. The coarse aggregate, 12 mm size
stone chipping, shall be hard, durable strong and
free from dust and organic matters.

UNIT 5: SPECIFICATION

Top Layer
The top layer is of 1:3 cement mortars, 12 mm
thick finished with a floating coat of neat
cement.

UNIT 6: RATE ANALYSIS

Theprocessofdeterminingrateperunitof
anyworkinCivilEngineeringprojectlike
earthwork,concretework,brickwork,
plastering,paintingetc.isknownas
AnalysisofRatesorsimplyRateAnalysis.

UNIT 6: RATE ANALYSIS
ProcedureofRateAnalysis
Theanalysisofratesisworkedoutforthe
unitpaymentoftheparticularitemofwork
undertwoheads:MaterialsandLabour.

UNIT 6: RATE ANALYSIS

The cost of items of work = Material cost +
Labour cost

Other costs included to the above cost of
items of work are:

Transportation cost (if conveyance more
than 8 km is considered.)

Water charges = 1.5 to 2 % 0f total cost

Contractor’s profit = 10 %

UNIT 6: RATE ANALYSIS
Material cost
Thecostsofmaterialsaretakenasdeliveredat
siteofwork.Thisisinclusiveof:

The first cost (cost at origin),

Cost of transport, railway freight (if any), etc.

Local taxes and other charges.

UNIT 6: RATE ANALYSIS
Lead statement

Thedistancebetweenthesourceofavailabilityof
materialandconstructionsiteisknownas
"Lead”andisexpressedinKm.Thecostof
conveyanceofmaterialdependsonlead.The
leadstatementwillgivethetotalcostofmaterials
perunititemincludingfirstcost,conveyance
loading-unloading,stackingchargesetc.

UNIT 6: RATE ANALYSIS
A typical lead statement is provided as follows
Sl.
No.
Material
s
UnitCost at
Source
(per
unit)
Lead
(in
Km)
Conveyance
charges (Per
Km/ Per
Unit)
Total
Convey
ance
charges
(/Per
Unit)
Total
Cost (In
Rs. /Per
unit)
1Rough
Stone
Cum250.00255.00 125.00375.00
2SandCum12.00204.00 80.0092.00

UNIT 6: RATE ANALYSIS
Labour cost

Toobtainlabourcostthenumberandwagesof
differentcategoriesoflabourers,skilled(Skilled1st
Class),semi-skilled(Skilled2ndClass)and
unskilled,requiredforeachunitofworkshouldbe
knownandthisnumberismultipliedbythe
respectivewageperday.

Thelabourchargescanbeobtainedfromthe
standardscheduleofrates.

UNIT 6: RATE ANALYSIS

30%oftheskilledlabourprovidedin
thedatamaybetakenas1stclass,
remaining70%as2ndclass.

UNIT 6: RATE ANALYSIS
Taskorout-turnwork
Thisisthequantityofworkwhichcanbedoneby
anartisanorskilledlabour(withthehelp
unskilledlabours)ofthetradeworkingfor8
hoursaday.

UNIT 6: RATE ANALYSIS
Task or out-turn work
S/N
Particular of Items Quantity of Work
per day
1Brick workin cement mortar in
foundation and plinth
1.25 cum /Mason
2Brick workin cement mortar in
Superstructure
1.25 cum /Mason
3Half brickwall in Partition 5 Cum /mason
4Brick workin cement mortar in
arches
0.55Cum /mason

UNIT 6: RATE ANALYSIS
S/NParticular of Items Quantity of Work per
day
512mm plastering with cement
mortar
8 squaremeter per
mason
6Pointing with cement mortar 10 sq. m per mason
7TerrazoFloor 6mmthick mosaic
work over 20mm cement
5 sq. m per mason
8Brick flat Floor in cement mortar 8sq. m per mason

UNIT 6: RATE ANALYSIS
S/NParticular of Items Quantity of Work
per day
9White washing or Color
washing one coat
200 sq. m per white
washer
10 White washing or Color
washing 3 coats
70 sq. m per white
washer
11Painting Door or Window one coat 25 sq. m per painter

UNIT 6: RATE ANALYSIS

Contractor’sprofit
Generallyaprovisionof10%ismadeinthe
rateanalysisascontractor’sprofitfor
ordinarycontracts.Forsmalljobs15%profit
andforlargejobs8%profitmaybe
consideredasreasonable.

UNIT 6: RATE ANALYSIS
Example
12mmthickplasterwithcement
mortar(1:6)

a)EstimationofMaterials
Assumeplasteringarea=100sqm
Hencevolumeofmortarfor12mm
plaster=100m×0.012m=1.2cum
Add30%moretotheabovevolumeforfilling
ofjoints,formakingununiform
surfacewellandforwastages

UNIT 6: RATE ANALYSIS
Thus total set volume of mortar including wastages and
joint filling etc.
Volume of dry material As, 1.25 cu m of dry volume
of mortar materials produces 1.0 cu m set
mortar;
s required for 1.56 cu m of set mortar is
= 1.25 ×1.56 cu m = 1.95 cu m,

UNIT 6: RATE ANALYSIS

Hence, volume of cement = 1.95/7 =
0.28 cu m.

Number of bags required = 0.28 /
0.0347 ≈ 8 bags.

Volume of sand required = 0.28 ×6 =
1.68 cu m.
b) Rate Analysis

Assume, the area of plastering = 100 sq. m.

UNIT 6: RATE ANALYSIS
ParticularsQ’ty/Nos.Rate (Frw)Cost (Frw)
Material Charges
1. Cement8 bags 12000 per bag96 000
2. Sand 1.68 cu m20000 per cu m33600

UNIT 6: RATE ANALYSIS
ParticularsQ’ty/Nos.Rate (Frw)Cost (Frw)
LabourCharges
1. Head Mason2 Nos 7000 per day14000
Mason 8 5000 40000
Helpers 10 3000 30000
Total Materials and Labour 213600
Add 1.5 % of water charges 3204

UNIT 6: RATE ANALYSIS

Add 10% Contractors profit: 21360
Grand Total 238,164 Frw
Rate per sqm = 238164 Frw /100 = 2381.64 Frw/m2

UNIT 6: RATE ANALYSIS
EXAMPLE 2
CementConcrete(1:2:4)forRCworkexcluding
reinforcementandformwork
a)EstimationofMaterials
AssumevolumeofR.C.C.=10cum(Setvolume)
1.54cumdryvolumeofconcretemaking
materialsproduces1.0cumsetconcrete
Thereforevolumeofdrymaterialsrequiredfor10cum
ofsetconcreteis15.4cum.

UNIT 6: RATE ANALYSIS

Sum of proportion of cement, sand and course
aggregate = 1+2+4 = 7

Hence, volume of cement = 15.4/7 = 2.2 cu m.

Number of bags required = 2.2 / 0.0347 ≈ 64 bags.

Volume of sand required = 2.2 ×2 = 4.4 cu m.

Volume of coarse aggregate required = 2.2 ×4 = 8.8
cu m.

UNIT 6: RATE ANALYSIS
b) Rate Analysis

Assume, volume of R.C.C. = 10 cu m.

UNIT 6: RATE ANALYSIS
ParticularsQ’ty/Nos.Rate (Frw)Cost (Frw)
Material Charges
1. Cement 64 bags 12000 per bag768000
2. Sand 4.4 cu m 20000 per cu m88000
3. C. aggregate8.8 cu m 30000 per cu m264000

UNIT 6: RATE ANALYSIS
ParticularsQ’ty/Nos.Rate (Frw)Cost (Frw)
LabourCharges
1. Head Mason1 10,000 per day10,000
2, Mason3 7,000 21,000
Helpers 15 4,000 60,000
ScaffoldingLS 100,000100,000
Total Materials and labours 1301000

UNIT 6: RATE ANALYSIS

Add 3% water charges Frw 39030

Add 10 % Cost of contingencies and supervision
=
130100

Add 20 %of benefits: 260200

Total=1730330

VAT 20 %=346,066
Grand Total 2,076,396 FRW
Rate per cum = 2,076,396/10 FRW = 207,639.6
FRW/cum

UNIT 6: RATE ANALYSIS

UNIT 6: RATE ANALYSIS

Example:
Duringtheconstructionofanevacuationcanalthe
needforconstructionofRCCslabbedwas
identified.Theslabisof6m*4m*0.2m.TheRCC
ratio:1:2:4

UNIT 6: RATE ANALYSIS

Reinforcements are R10 and R8 for the first and
the second bed respectively, the spacing between
steel bars is 20cm in both cases.

R10/12m costs 6500Frw, R8/6m costs 4000Frw,
Labor cost is
5000Frw/mason/0.5m3
and 2500Frw/helper/0.5m3 of concrete dry
volume

Formwork wood of 2cm*20cm*4m length is of
3500Frw/piece

Sand is 55000Frw/5m3

Aggregate is 70000Frw/5m3

UNIT 6: RATE ANALYSIS

Contingencies and supervision is 10% of cost
of materials and labour

Cement: 10500Frw/Bag

Interest cost is 20% and VAT cost is 18% of
the total cost

Determine the cost for RCC slab

Determine the rate of 1m3 of that RCC
slab

UNIT 6: RATE ANALYSIS
Solution

Calculation of volume of concrete for the slab =
6*4*0.2= 4.8m
3
(wet concrete)

Calculation of volume of concrete for the slab =
4.8*1.52 = 7.296m
3
(dry concrete)

UNIT 6: RATE ANALYSIS

Calculation of quantities of materials
required

Cement

Calculation of volume of cement =
(1/(1+2+4))*7.296= 1.042286m
3

Weight of cement= 1.042286 m
3
*1440kg/m
3
=
1500.891 kg

Number of bags of cement = 1500.891/50= 30
Bags

Cost of cement= 30 Bags *10500Frw/Bag =
315000Frw

UNIT 6: RATE ANALYSIS
Sand

Calculation of volume sand = (2/(1+2+4))*7.296 =
2.084571m
3

Cost of sand =2.08457*55000/5= 22930.29
Frw
Aggregate

Calculation of volume= (4/(1+2+4))*7.296 =
4.169143m3

Cost of Aggregate =4.169143*70000/5=
58368 Frw

UNIT 6: RATE ANALYSIS
Formwork

Area of one wooden piece = 4*0.2 =0.8m
2

Area of slab = 4*6 =24 m
2

Number of pieces required for the base of slab =
24/0.8 = 30 Pieces

Additional pieces for the sides = 5 Pieces

Total number of pieces = 30+5 =35 Pieces

Cost of formwork =35*3500= 122500 Frw

UNIT 6: RATE ANALYSIS

Reinforcements

Number of steel bars (R10) for the first layer = [(6-
0.1)/0.2] +1= 30.5 Steel bars

> 30.5 pieces of 3.9m are required i.e 10 bars of
12m.

Total length of steel bars (R10) for the first layer =
10*12m=120m

Cost of steel bars (R10) for the first layer =
10*6500Frw= 65000 Frw

Number of steel bars (R8) for the second layer =
[(4-0.1)/0.2]+1 = 20.5 Steel bars of 5.9 m.

UNIT 6: RATE ANALYSIS

Total length of steel bars (R8) for the second layer = 21
steel bars of 6m.

Cost of steel bars (R8) for the second layer =
21*4000Frw/6m= 84000 Frw

UNIT 6: RATE ANALYSIS

Cost of labours = (5000+2500)*7.296/0.5=
109440 Frw

Cost of materials and labour = 315000Frw +
22930.29 Frw + 58368 Frw + 122500 Frw +
65000 Frw + 84000 Frw + 109440 Frw =
777238.29

Cost of contingencies and supervision =
777238.29 *10/100 = 77723.829 Frw

Interest = 777238.29 *20/100= 155447.658
Frw

UNIT 6: RATE ANALYSIS

VAT = 777238.29*18/100= 139902.829 Frw

Total cost of the RCC Slab = 1147352.606 Frw

The rate of 1m3 of RCC Slab = 1147352.606 /4.8 =
157257.758Frw

UNIT 6: RATE ANALYSIS

UNIT 7. VALUATION
Valuation is the technique of determination
of fair price of a property such as land,
building, factory or other structures.

UNIT 7. VALUATION
Purpose of the Valuation

The main purposes of valuation are as
follows:

Sale or Purchase of a property

To fix up the municipal taxes,

To fix up the gift tax payable to the
government when the property is gifted to
somebody else.

UNIT 7. VALUATION

Todividethepropertyamongthe
shareholdersincaseofthepartition.

Assessmentofincome

RentFixation

Toworkouttheinsurancevalueofa
property

Forcompulsoryacquisitionoftheproperty
bygovernment,forpublicpurpose

UNIT 7. VALUATION
TERMINOLOGY
Bookvalue
Bookvalueistheamountshownintheaccount
bookafterallowingnecessarydepreciations.The
bookvalueofapropertyataparticularlyyearis
theoriginalcostminustheamountof
depreciationuptothepreviousyear.

UNIT 7. VALUATION
TERMINOLOGY
Market valueThemarketvalueofapropertyistheamount,
whichcanbeobtainedatanyparticulartime
fromtheopenmarketifthepropertyisputfor
sale.Themarketvaluewilldifferfromtimeto
timeaccordingtodemandandsupply.

UNIT 7. VALUATION
TERMINOLOGY

Outgoings:thesearetheexpenseswhichare
requiredtomaintaintheproperty.Theseincludes:
Taxes,periodicrepairs,management,andlossof
rent

UNIT 7. VALUATION

Scrap value
Ifabuildingistobedismantleaftertheperiodits
utilityisover,someamountcanbeobtained
fromthesaleofoldmaterials.Theamountis
knownasscrapvalueofabuilding.Scrapvalue
variesfrom7%to10%ofthecostof
constructionaccordingtotheavailabilityof
thematerial.Scrapvalueisalsoknown
ResidualValue.

UNIT 7. VALUATION
FactorsAffectingValueofaBuilding

Type of the building

Location

Building structure and durability

The quality of materials used in the construction

Size of the building

UNIT 7. VALUATION
Depreciation

Itisthelossinvalueofabuildingorproperty
duetostructuraldeterioration,decay.Itdepends
onuse,age,natureofmaintenanceetc.
.

UNIT 7. VALUATION

Calculation of Depreciation
Method of depreciation
•
Straight line method

Constant percentage method

Sinking fund method

Quantity survey method

UNIT 7. VALUATION

Straight line methodItisassumedthatthepropertyloosesitsvalueby
thesameamounteveryyear. Therefore,the
annualdepreciation“D”isestimatedas:

UNIT 7. VALUATION

UNIT 7. VALUATION

Example:
Whatisthestraight-linedepreciation
expenseforatruckthatwaspurchasedfor
$30,000withalifetimeof4yearsandhasa
residualvalueof$2,000?Prepareafour-
yeardepreciationscheduleforthetruck.

UNIT 7. VALUATION
Solution:
Depreciation expense = (30,000 − 2,000) / 4 =
$7,000 per year The four-year depreciation
schedule:

UNIT 7. VALUATION
Rateofdepreciationiscalculatedas
follows:

UNIT 7. VALUATION
Considerthefollowingexample,theoriginalcost
oftheassetisRs.250,000.Theusefullifeofthe
assetis10yearsandnetresidualvalueis
estimatedtobeRs.50,000.Now,theamountof
depreciationtobechargedeveryyearwillbe
computedasgivenbelow:

UNIT 7. VALUATION

UNIT 7. VALUATION
AdvantagesofStraightLineMethod
StraightLinemethodhascertainadvantageswhich
arestatedbelow:

Itisverysimple,easytounderstandandapply.
Simplicitymakesitapopularmethodinpractice;

Everyyear,sameamountischargedas
depreciationinprofitandlossaccount.This
makescomparisonofprofitsfordifferent
yearseasily;

UNIT 7. VALUATION
Limitations of Straight Line Method

Thismethodisbasedonthefaultyassumption
ofsameamountoftheutilityofanassetin
differentaccountingyears;

UNIT 7. VALUATION
Written Down Value Method
Bookvaluekeepsonreducingbytheannualchargeof
depreciation,itisalsoknownas‘reducingbalance
method’.Theamountofdepreciationreducesyear
afteryear.

UNIT 7. VALUATION

Forexample,theoriginalcostoftheassetisRs.
200,000anddepreciationischarged@10%p.a.
atwrittendownvalue,thentheamountof
depreciationwillbecomputedasfollows:

UNIT 7. VALUATION

UNIT 7. VALUATION
Underwrittendownvaluemethod,therateof
depreciationiscomputedbyusingthe
followingformula:

UNIT 7. VALUATION
Where, R = Rate of depreciation
n = Expected useful life
s = Scrap value
c = Cost of an asset
Forexample,theoriginalcostofatruckisRs.
900,000anditsnetsalvagevalueafter16years
ofusefullifeisRs.50,000thentheappropriate
rateofdepreciationwillbecomputedasunder:

UNIT 7. VALUATION

UNIT 7. VALUATION
Constant percentage method or
Declining balance method
Inthismethodthepropertyisassumedto
loosevalueannuallyataconstant
percentageofitsvalue(bookvalue).

UNIT 7. VALUATION

UNIT 7. VALUATION

Hence, at the end of n years value of the property
becomes ultimately the scrap value the scrap
value
.

UNIT 7. VALUATION

SalvageValue
Thevalueofbuildingattheendofutilityperiod
withoutbeingdismantlediscalledtheSalvage
Value.

UNIT 7. VALUATION

UNIT 7. VALUATION
Valuation Method commonly used in Rwanda

UNIT 7. VALUATION

UNIT 7. VALUATION

Valuation Method commonly used in
Rwanda

UNIT 8: HEXAGONAL ROOMS
For rooms which are circular, semi circular, hexagonal,
half hexagonal, etc, the total centre line length of all
walls may be found out and the quantities may be
calculated multiplying the respective breadth and
height. For semi circular, half-hexagonal, etc, the
centre line length (mean length) of these portions, are
also found out dealt separately

HEXAGONAL ROOMS

HEXAGONAL ROOMS

Example.
The plan and part cross-section of a hexagonal room are
given in figure 1 (above). Estimate the quantities of:
•
Earthwork in excavation in foundation,
•
Lime concrete in foundation,
•
Stone masonry in foundation and plinth in lime mortar.
•
Damp proof course,
•
Brickwork in superstructure in lime mortar,
•
RCC work in roof including eave and lintel
•
Lime concrete in roof terracing
•
2.5cm C.C over 7.5cm LC floor and.
•
12mm cement plastering 1:6 inside and outside walls

HEXAGONAL ROOMS

The length of the centre and the area of the
hexagonal may be calculated as below
Figure 2 represents 1/6 of the hexagonal. The sides of
the hexagonal form equilateral triangles at the centre.

HEXAGONAL ROOMS
Therefore, total length of centre line=6*3.23=19.38m

HEXAGONAL ROOMS

Floor area=6* area of one inside triangle
=6*(1/2*3*3*1/2*tan60)=6*1/2*3*3*1.732*1/2=23.38
sqm

Roof area=6*area of one outside triangle

=6*(1/2*3.46*3.46*1/2*1.732) =31.10sqm

HEXAGONAL ROOMS

ESTIMATION OF EXCAVATION OF FARM
POND

ESTIMATION OF EXCAVATION OF
FARM POND

ESTIMATION OF EXCAVATION OF FARM
POND

ESTIMATION OF EXCAVATION OF FARM POND

Estimate of a Building with Jack
Arch and Arch Openings
INTRODUCTION

Architectsalwayswishtoaddbeautyandeleganceto
buildings.Alsothepubliclikethewayinwhichitlooks
asattractiveandbeautifulwithrespecttothe
surroundings.

Itbecamecustomarytoaddarchesfortheopenings
notonlyoutsidethebuildingbutalsoforthedoorand
otheropenings.Whentheseaddshapesareaddedit
becomesachallengetostructuralengineerswith
respectthedimensionaldesignaspect.

Estimate of a Building with Jack Arch
and Arch Openings

TYPES

SEMI-CIRCULARARCH

Estimate of a Building with Jack Arch
and Arch Openings
SEGMENTAL ARCH

Estimate of a Building with Jack Arch
and Arch Openings
ELLIPTICAL ARCH

Estimate of a Building with Jack Arch
and Arch Openings
JACK ARCH

Estimate of a Building with Jack Arch
and Arch Openings
TRIANGULAR ARCH

Estimate of a Building with Jack Arch
and Arch Openings

Estimate of a Building with Jack Arch
and Arch Openings
TECHNICAL TERMS
The various technical terms used in arches are as
follows:
1)Abutment:-This is the end support of an arches.
2)Pier:-This is support of intermediate of an arch.
3)Intrados:-This is the inner curve or surface of an
arch.

4)Extrados:-This is the outer curve or surface of
the arches.

5)Voussoirs:-The voussoirs or arch stones are the
wedge shaped units forming the arch.

Estimate of a Building with Jack Arch
and Arch Openings

Estimate of a Building with Jack Arch
and Arch Openings

11)Span:-This is the clear horizontal distance
between the two supports.

12)Rise:-this is the vertical distance between the
crown and springing line.

13)Depth of arch:-This is the perpendicular
distance between the intrados and extrados.

14)Haunch of an arch:-This is the portion of arch
situated centrally between the key and skew backs.

Estimate of a Building with Jack Arch
and Arch Openings

ARCHESANDFORMULASTOBEUSED
Mainlycivilengineeringworksusetwotypesofarches:Semi-circular
shape
onecancalculatethemasonry(brickorstonework)inthearchringin
cubicmeters(Q)as,

Estimate of a Building with Jack Arch
and Arch Openings
where,
r = inner radius of the arch ring,
t = thickness of the arch ring,
b = breadth of arch ring, i.e. the dimension
perpendicular to paper,
•π(r+ t/2) = π ×(central radius of the ring)
=length of arched masonry.

Estimate of a Building with Jack Arch
and Arch Openings
Segmental Arch
When a semi -circular arch (subtending an angle of π radians
(180
o
) at the centre of the corresponding circle) is cut short –
Figure 3.6 –on either side so that the segment ABCD
subtends an angle (θ) that is less than 180
o
, at the centre, we
get a segmental arch. Its span DC is, obviously, less than the
diameter of the parent circle. Therefore, the cubic content of
masonry contained in this segmental arch (which is bunits
long –perpendicular to paper) is given by :

Estimate of a Building with Jack Arch
and Arch Openings

Estimate of a Building with Jack Arch
and Arch Openings

Opening deduction for segmental arch

Estimate of a Building with Jack Arch
and Arch Openings

SEPTIC TANKS
Components of a Septic System
A septic system consists of four main components:
1) Connecting Pipe
2) Inspection Chamber
3) Septic Tank
4) Soak Pit

SEPTIC TANKS
Connecting Pipe:
The wastewater from the toilet flows to the septic
tank through the connecting pipe. The minimum
diameter of the pipe should be 4 inches
(=10.16cm). The pipe should be made of material
that is corrosion free such as PVC, cast iron

SEPTIC TANKS

SEPTIC TANKS
Inspection Chamber:
Thechamberliesintheconnectingpointof
sewerlinescomingfromdifferenttoiletsandwhere
thereisachangeinthedirectionoftheflow of
wastewateranddiameterofthepipes.
The inspection chamber provides easy access
for cleaning or clearing of any blockages. The
inspection chamber must be covered securely.

SEPTIC TANKS
Septic Tank:
Theseptictankcollectsandstoressewagefromthe
households.Theseptictankcontainsanaerobic
bacteriathatdecomposesordisintegratesthesewage.
Thematerialusedintheconstructionofseptictank
rangefromstoneorbrickmasonrytoconcretefora
biggercommunityseptictank.Itisusuallyburied
underground.

SEPTIC TANKS
Soak Pit
Functions of a Septic Tank
The essential functions of a septic tank are:

To collect wastewater from the house.

To act as a sedimentation tank. As the sewage enters
the tank,

SEPTIC TANKS
…for primary treatment of wastewater in the tank, as
the solids and the liquids are partially
decomposed by anaerobic bacteria and other
natural processes.

To pass the effluent into the soak pit for final
treatment and disposal.

SEPTIC TANKS
Tank Configuration
Thecommonlyusedseptictankhastwo
compartments.Theplanandsectionoftheseptic
tankareillustratedasbelow:

SEPTIC TANKS

SEPTIC TANKS
Key components of a Septic Tank
Base
Thebaseisusuallyconstructedofconcretewiththethickness
ofabout100-150mm.Thisistheminimumthickness
requiredtowithstandtheupliftpressurewhenthe
tankisempty.Thebasealsoactsasafoundationforthe
sidewalls.Adesignermayalsoreinforcethebaseslabin
largertanks.

SEPTIC TANKS
Side Walls
Thesidewallsoftheseptictankaremadeofbrick,
masonryorconcrete.Theseptictankmustbe
watertight.
Manhole
The manhole provides an access to the compartments
in the septic tank.

SEPTIC TANKS
InletandOutlet

Thecorrectinstallationoftheinletandoutletare
criticalintheperformanceoftheseptictank.The
wastewatermustenterandleavethetankwith
minimumdisturbance.
Thearrangementofinletandoutletwiththeminimum
requireddimensionsisgiveninFigure6below.

SEPTIC TANKS

Figure . Arrangement of Inlet and Outlet with
Dimensions

SEPTIC TANKS
…somesludgeaccumulatesandthetankmustbe
desludgedatregularinterval,usuallyonceeveryone
tofiveyears.
Septictankcanbeuseduptocommunityof
about300.

SEPTIC TANKS

SEPTIC TANKS

Aseptictank isakeycomponentofa septic
system,asmall-scalesewagetreatment system
commoninareasthat lackconnectiontomain
sewagepipes providedbylocalgovernmentsor
privatecorporations.

SEPTIC TANKS

Thebafflewallpreventsthescumfrom
flowingoutoftheseptictankwithout
treatment.Italsofacilitatesinthesmoothsettlingof
thesludge.Thebafflewallhasslotsoropeningsthat
allowthesewagetoflowfromonecompartmentto
anotherasshowninFigure7.

SEPTIC TANKS
Figure 7. Section BB

SEPTIC TANKS
Ventilation
Thedecompositionoftheorganicwastesproduce
gasesandthesafeexitofthegasesmustbe
providedintheseptictank.
Thesimplestoptionistoinstallaventpipewithascreen
ontheroofslaboftheseptictank.

SEPTIC TANKS
Maintenance of a Septic Tank
• Check for any structural damage to the septic tank
regularly and repair if necessary.

Empty the septic tank when the sludge reaches a
depth of 2/3 full or at least every two years.

SEPTIC TANKS
Maintenance of the Pipes and Fittings
Check all the connecting pipes and fittings and repair
or replace when required.
Maintenance of Soak Pit
Clean and clear any blockages in the pipes and the
soak pit

SEPTIC TANKS
Potential System Problems Signs of a failing
system are:

Slow draining toilets or fixtures.

Sewage back flow into the house.

Sewage odours near the field or tank.

Neighbours complaining about your septic system.

SEPTIC TANKS
Figure . Sewage overflow from septic tank

SEPTIC TANKS
Preventing System Problems
DO’S

Check the sludge depth in your septic tank every year
and empty when it is two thirds full.

Promptly repair leaky water.

Prevent surface water runoff from entering into
your septic tank.

Keep the records of emptying, inspections, and other
maintenance works done.

Ensure that tenants understand how to safely operate
and maintain the septic system.

SEPTIC TANKS
DON’TS

Avoiddrivingorparkingoveranypartofyourseptic
system.Theareaoverthesystemshouldbeleft
undisturbedwithjustamowedgrasscover.Roots
fromnearbytreesorshrubsmaydamageyoursystem.

Don’tputanylargequantityofcookingoilor
greaseintothesepticsystem.

Don’t throw non-biodegradable materials sanitary
products or plastic into the septic system

Don’t use the septic tank as a garbage disposal

SEPTIC TANKS
Septic Tank Emptying

Donotwaituntilyoursystemshowssignsoffailureto
haveyourseptictankemptied.Thewaitingtimecan
completelyclogthetank,resultinginheavyrepair
charges.

Check the sludge depth of your septic tank every year.
When it is two thirds full call the municipal office for
emptying
.

SEPTIC TANKS
How to Check your Septic Tank

SEPTIC TANKS

SEPTIC TANKS
When & How to Empty your Septic Tank

SEPTIC TANKS

SEPTIC TANKS
Septic Tank Supervision Check List
S/NDescription of Items Rem
arks
Presence of all components of the septic system
(pipe, inspection chamber, septic tank and soak
pit).
All the dimensions of the septic tank are as per
approved drawing or table incorporated in the
manual.
The effluent from the septic tank is connected
to a soak pit.
Presence of an access through the manhole in
both the compartments of
the roof slab.

SEPTIC TANKS
S/
N
Description of Items Rem
arks
The baffle wall is placed at two thirds of the length
from the inlet wall
(Septic tank with two compartments).
Pipes and fittings
The outlet pipe is 50mm lower than the inlet pipe.
The septic tank has a vent pipe with a height of not
less than an averagehumanheight.
The minimum diameter of the connecting pipes is
110mm.

SEPTIC TANKS
Designing and making a system
InitialDesign

Chooseasuitablelocation.Thisshouldbedownhill
fromthesourceofsewage.Atleast15mfromthe
nearestwatersupply.

Itshouldbeatleast3mfromthenearest
building.

Drawaplanshowingtheseptictankand
distancestodwellings,propertylines,wells,water
sourcesandanyotherprominentmanmadeor
naturalfeatures.

SEPTIC TANKS

Calculatethevolumeofthetank.Thevolumeconsists
oftwocomponents.SludgestorageandLiquid
retentionvolume.

SEPTIC TANKS
Tank design
The tank is considered to be made up of four zones,
each of which serves a different function:

scum storage zone

sedimentation zone

sludge digestion zone and

digested sludge storage zone

SEPTIC TANKS
Scum storage zone
Scumaccumulatesatapproximately30to40
percentoftherateatwhichsludgeaccumulatesandso
thetankvolumeforscumstorage(V
sc
,m
3
)canbe
takenas0.4V
sl

SEPTIC TANKS
Sedimentation zone
Thetimerequiredtopermitsedimentationof
settleablesolids
t
h
=1.5-0.3logPq With:
t
h
=minimummeanhydraulicretentiontimefor
sedimentation,days
P=contributingpopulation,q=wastewaterflowper
person,l/day.

SEPTIC TANKS
The value of t
h
used should not be less that 0, 2 day. The
tank volume for sedimentation (Vh, m
3
) is given by:
Vh = 10
-3
Pqt
h

SEPTIC TANKS
Sludge digestion zone
The time needed for anaerobic digestion of the
settled solids (t
d
, days) varies with temperature (T, C)
as shown in the and given by the equation below:
t
d
= 1853 T
-1.25
(The sludge digestion time at various temperatures are
given on separate sheet) The volume of the sludge
digestion zone (V
d
, m
3
) is given by:
V
d
= 0, 5 * 10
-3
Pt
d

SEPTIC TANKS
Digested sludge storage zone
Thevolumeofthesludgestoragezonedepends
ontherateofaccumulationofdigestedsludge
(r,m
3
perpersonperyear)andtheinterval
betweensuccessivedesludgingoperations(n,
years).
Forn<5:r=0.06m
3
/personyear
Andn>5r=0.04m
3
/personyear
Thesludgestoragevolume(V
sl
,m
3
)isgivenby:
V
sl
=r*P*n

SEPTIC TANKS
Overall design capacity
The overall design capacity of the septic tank (V, m
3
)
is the sum of the volumes required for scum storage,
sedimentation, digestion and sludge storage:
V=V
sc
+V
h
+V
d
+V
sl
SinceV
sc
isaround0,4V
sl
thisbecomes:
V=V
h
+V
d
+1,4V
sl

SEPTIC TANKS
Overall design capacity
Where
V= Total Volume
V
sc =
volume for scum storage
Vh = volume for sedimentation
V
d =
The volume of the sludge digestion zone
V
sl =
The sludge storage volume

Two compartment tank
The tank should be divided into two compartments. The
first should be twice as big as the second.

SEPTIC TANKS

SEPTIC TANKS
Design example
Design a septic tank to serve a family of 6 persons
whom produce 100lcd. The design temperature is
25
o
C.

Tank design:

Sedimentation tank:

th = 1.5 –0.3 log (Pq) = 1. 5 –0. 3 log (6*100) =
0. 67 days

Vh = 10
-3
Pqt
h

= 10
-3
*6*100*0. 67 = 0. 4 m
3

SEPTIC TANKS
Sludge digestion
t
d
= 1853T
-1.25
= 33.1474 days
V
d
= 0, 5 *10
-3
P t
d
= 0, 5 *10
-3
*6* 33.1474
= 0,099m
3

SEPTIC TANKS
Digested sludge storage
Choosing n= 2 years and r = 0,06m3 per person per
year

Vsl = r*P*n = 0, 06*6*2 = 0,72m
3

SEPTIC TANKS
Overall effective tank
V= V
h
+V
d
+1, 4 V
sl
= 0, 4 + 0,099 + (1, 4*0, 72) = 1, 5 m
3
Using a two compartment tank, with the first
compartment 1m
3
in volume and the second 0, 5 m
3

COST ESTIMATE OF SEPTIC TANK: Example 1

COST ESTIMATE OF SEPTIC TANK

ESTIMATION OF QUANTITIES
OF STEEL & R.C.C. ELEMENTS
Example 1: Prepare the bar bending schedule of the given figure for R.C.C.
beam.

EXERCISE
1)Prepare the Bar bending schedule for the beam shown below.


Prepare the Bar bending schedule of a simply
supported R.C.C. Lintels from the following
specification:

Size of lintel 300mm wide x 200mm depth. Main
bars in tension zone of Fe 250(grade I) 3 bars of
16mm dia., one bar is cranked through 45
0
at 170mm
from each end

2 No. anchor bars at top 8mm dia.

Two legged stirrups@150mm c/c of 6mm dia.
throughout.

Clear span of the lintel is 1150mm.

Bearing on either side is 150mm.

Unit 7. EARTHWORK CALCULATIONS
7.1 Introduction
GenerallyalltheCivilEngineeringprojectslikeroads,
railways,earthdams,canalbunds,buildingsetc.
involvesearthworkcalculations.Thisearthworkmay
beeitherearthexcavationorearthfillingorSome
timesbothaccordingtothedesiredshapeandlevel.
Basicallythevolumeofearthworkiscomputed
fromlength,breadth,anddepthofexcavationor
filling.

Unit 7. EARTHWORK CALCULATIONS

Unit 7. EARTHWORK CALCULATIONS
Case 1)
When there is no
longitudinal slope

Unit 7. EARTHWORK CALCULATIONS
Case 2) When the ground is in longitudinal slope

Unit 7. EARTHWORK CALCULATIONS
i)

Unit 7. EARTHWORK CALCULATIONS

Unit 7. EARTHWORK CALCULATIONS
7.4 Additional explanation about road earthworks
The final road alignment is a suitable combination of
uphill/downhill slopes, and curves but also construction
costs due to movements of soil and rocks.
Earthworks are a crucial matter for road construction
cost. Road engineers must study and minimise them
Their computations can be performed either manually
or with a computer

Unit 7. EARTHWORK CALCULATIONS
During earthworks study, cuttings and embankments
are determined using cross-sections and longitudinal
profiles

Unit 7. EARTHWORK CALCULATIONS
Example of a road vertical alignment layout (longitudinal profile)

Unit 7. EARTHWORK CALCULATIONS
Knowing a certain number of soil properties, volumes
to be displaced are calculated
The computation of earthworks helps in determining
the following points:
The haul distance (distance of soil displacement) and
the equipment to be used
Land acquisition (compensation cost for right-of-way
acquisition)
Earthworks cost
Organisation and planning for site installations

Unit 7. EARTHWORK CALCULATIONS
Soil properties to be considered during earthwork computation
Compaction factor and Shrinkage factor
-> A compaction factor is a characteristic assigned to
a specific earth material which indicates how, and to
what extent, its volume will change when that
material, after having been cut from the original
ground, is compacted as fill material.
-> When earth is excavated and hauled for use as
compacted fill, its volume once compacted is,
according to the type of soil, less than its original
volume before it was excavated. This difference is
defined as “shrinkage”.

Unit 7. EARTHWORK CALCULATIONS
Swell factor
-> When soil materials are excavated, they, according
to their properties, occupy a larger volume due to the air
voids that are introduced into the material. => This
increase is called 'swell' or 'bulking'.

Unit 7. EARTHWORK CALCULATIONS

Unit 7. EARTHWORK CALCULATIONS
Three types of cross-sections are encountered

Unit 7. EARTHWORK CALCULATIONS
Mass-Haul diagram
The estimation of the quantity of material which
must be excavated (cut), and the quantity of material
required to raise the elevation of the existing ground
(fill), is very useful in the development of a cost
estimate for a project. => additional costs for soil
movements can be avoided if the cut and fill
quantities are in balance

Unit 7. EARTHWORK CALCULATIONS
A Mass-haul diagram is a useful method to
graphically represent the amount of material that will be
cut and used for fill on any earthwork job, particularly for
highway or railway projects
At the end of every computation an ordinate of the
Mass-Haul diagram is found and a curve is drawn
(cumulative volume of material against distance)
Below is an exercise shows how mass haul diagrams
are calculated and sketched

Unit 7. EARTHWORK CALCULATIONS

Unit 7. EARTHWORK CALCULATIONS
Freehaul(F):Whenmaterialisexcavated,
constructioncontractorswillnormallymoveitover
anestablisheddistancefreeofcharge.
Thisdistanceisthe"freehaul",andisnormally
agreeduponbetweentheclientandbuilder.
Overhaul (O): Overhaul is defined as the distance
over which the excavated material must be
hauled, less the free haul distance. The cost for
overhaul is normally specified by the contractor.
This rate is normally given in RWF/m
3
/unit-distance
or $/m
3
/unit-distance.

Unit 7. EARTHWORK CALCULATIONS
Borrow (B):Borrow refers to the fill material that
must be brought to the proposed highway site
from outside the highway corridor. Borrow does
not include the material that is excavated on site
for use as fill. The borrow cost is normally given
RWF/m³ or $/m³, and this rate normally includes
the cost of excavating and transporting borrow.
Limit of Economic Overhaul (L): The limit of
economic overhaul is a distance beyond which
it is not economic to overhaul. At this point, the
cost to excavate and overhaul on-site material is
equal to the cost of excavating and delivering
borrowed material.

Unit 7. EARTHWORK CALCULATIONS
Waste (W): Waste is the excavated material that
cannot be used for fill on the project site. Normally,
the designer will try to roughly balance the amount
of cut and fill required on a project at the design
stage, so that the amount of fill that must be
transported in (borrow) or the amount of waste that
must be hauled away are not excessive.

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