Building Construction and Technology

BUILDING CONSTRUCTION TECHNOLOGY
ACKNOWLEDGEMENT
I would like to start by thanking God the almighty who from creation endowed us with
knowledge, wisdom and understanding. I thank the British College of Applied Studies for
giving me the opportunity to have QS HND program. I gathered a vast knowledge from
successful assignment.
My special thanks go to Mr.M. Suhoothi. The Building Construction Technology
lecturer, for giving me the guidance through advice to make this assignment a success. My
infinite thanks to Site Engineer for providing me the information about the construction
works. Finally, to those who are close to me, my friends, and my colleagues who supported
me unconditionally to pursue all my ambitious.
Thank you.

CONTENT
ACKNOWLEDGEMENT ......................................................................................................................................................1
CONTENT .................................................................................................................................................................................2
INTRODUCTION....................................................................................................................................................................3
TASK – 01..................................................................................................................................................................................4
1.1 IDENTIFYTHE VARIOUS FACTORS CONSIDERED IN SITE SELECTION .............................................4
1.2 DESCRIBE THE STAGES IN SITE INVESTIGATION TO INTENDED PROJECT SCHEME. .................7
1.3 EXPLAIN THE CLASSIFICATION OF SOIL AND DESCRIBE THE SOIL INVESTIGATION
METHODS TO SELECT SITE LOCATION. ........................................................................................................11
TASK-02..................................................................................................................................................................................15
2.1 DESCRIBE DIFFERENT TYPES OF FOUNDATION AND DISCUSS VARIOUS FACTORS
CONSIDERED IN SELECTING A SUITABLE FOUNDATION FOR INTENDED PROJECT SCHEME.
.........................................................................................................................................................................................15
2.2 DESCRIBE THE METHOD OF EXCAVATION SUITABLE FOR THE SELECTED FOUNDATIONS
WORK AND ASSOCIATED TEMPORARY WORK FOR YOUR INTEND PROJECT. ............................21
2.3 IDENTIFY THE STEPS IN THE PROCESS OF CONSTRUCTING THE SELECTED FOUNDATIONS.
.........................................................................................................................................................................................24
TASK-03..................................................................................................................................................................................26
3.1 IDENTIFY AND DISCUSS THE FORM WORK NEEDED FOR THE CONSTRUCTION OF BUILDING
ELEMENTS AND THEIR SUPPORTING FOR THE RESIDENTIAL BUILDING......................................26
3.2 EXPLAIN THE REINFORCEMENT ARRANGEMENT OF IN-SITU CONCRETE MEMBERS.............31
3.6 DISCUSS THE BLOCK WORK CONSTRUCTION IN THE RESIDENTIAL BUILDING & ECONOMIC
DEDICATED CENTRE. ............................................................................................................................................36
3.7 DESCRIBE THE FOLLOWING WORK FOR PLASTERING OF EXTERNAL AND INTERNAL WALL
AND THE WORK IN RESIDENTIAL BUILDING/ECONOMIC DEDICATED CENTRE........................40
3.8 IDENTIFY THE ELEMENTS TO BE WATER PROOFED IN THE RESIDENTIAL BUILDING AND
ECONOMIC DEDICATED CENTRE AND EXPLAIN THE METHOD OF WATER PROOFING FOR
WASH ROOMS & TOILET IN THE BUILDING.................................................................................................44
3.9 EXPLAIN AND WRITE METHOD STATEMENT FOR THE METHOD OF CONSTRUCTION OF PRE-
TENSIONED AND POST-TENSIONED BEAMS IN ECONOMIC DEDICATED CENTRE. ...................49
3.10 DISCUSS THE METHOD OF JOINING AND INSTALLING THE TIMBER WORK IN PREPARATION
OF ROOF FOR RESIDENTIAL BUILDING.........................................................................................................51
CONCLUSION.......................................................................................................................................................................55
REFERENCES........................................................................................................................................................................56

INTRODUCTION
Building construction is one of the fastest growing industries in the modern
world. Nowadays man depends on construction. At the present time buildings are constructed
for two purposes. There are residents or commercial purpose. A Quantity Surveyor job is
interconnected with construction. Therefore a Quantity Surveyor must modernize the
knowledge on advancement of technology related to construction.
Construction outputs are totally different from
manufacturing products; it’s because of its complexity and tedious amount of works. A better
quality building can be achieved by following standard tasks which were approved by the
professional construction institutions. Deep considerations should be taken from the site
selection to end of construction of the building. Also risks and practical problems depend on
the place and type of construction
In this assignment we will contract a new two storied
residential building to construed. The building is included a hall, store room, and office room
and kitchen at ground floor and at first floor level three bed room with bath rooms.

TASK – 01
1.1 IDENTIFY THE VARIOUS FACTORS CONSIDERED IN SITE
SELECTION
Different matters should be measured while selecting a building site. The high cost of land
and planning controls normally combine to prevent the acquisition of the perfect site. Really
many sites are now being developed which in years gone by would have been considered
unsuitable. Some of the important factors are investigated.
1. Safety: The leading safety hazards on site are falls from height, motor vehicle crashes,
excavation accidents, electrocution, machines, and being struck by falling objects. So
many construction contractors and workers have need safety.
2. Location: We consider about the location, laborers, electricity, transport and the
environmental impact during and after the construction of the building is should be
free from noises.
3. Soil condition: Soil can be described in many different ways. Such as heavy, light,
sandy, clay, loam, poor or good. So, it's describe to Color Compaction, Moisture
content, Structure, Texture and these factors We will provide a brief overview of our
building.
4. Topography: The surface area of the site is smooth and there was a floor part of
demolished building.
5. Size & shape: it has required size and shape. In front of the site there is big space so
materials can store easily such as sand, brick, aggregate and reinforcement etc.
Workers can work easily too.
6. Accessibility: It is near to the main road, private library, hospital, post office, police
station, Ceylon travel board, bus stop and mosque. All facilities are available here.
7. Utilities: we will observe in this site have water supply facilities, electricity supply
facilities and sewer collection system
8. Cost : we will calculate how much cost this site
9. Availability: We can get all the materials easily because this site is in town area.
Name of the town we already mentioned that Kattankudi. It is famous for making
bricks and sand exploring.

10. Drainage: There is no drainage system near the site. But they hope in little period its
will be come. It is not a big problem because they keep a slope in the site area so
water can beflow.
11. Local Government & State regulations: They have taken the approval for build this
building from D.S office and also they have taken approval for construct the fit from
the D.S office.
They have taken the approval from electricity board for construct an electricity supply
for this building.
Select Suitable Location for intended Project Scheme
A – Economic dedicated center
B – Residential Building
C – Ground Stadium
Reasons:
A – ECONOMIC DEDICATED CENTER
 We should know can we transport the
construction material easily and are there
any highways near the site. This place “A” is near the main site, so, we can easily
transport construction materials, and the construction materials are available near the
site
 We want water supply facilities at our site or near the site; this place “A” must have
water supply facilities, because this place is near the main site, so water supply
facilities are available in this site
 We want Electricity supply facilities at our site. Commonly main street site areas are
should be have electricity facilities. So, our location “A” is near the main street site.
So, this “A” place is should be have electricity facilities

 This place “A” has Accessibility facilities, for ex: this place has public infrastructure
facilities, and road facilities. This location is main street site, so these facilities are
should behave. So these facilities are very very easy to construction work.
 This Place “A” is very safety place. The place is protected from natural disasters for
example tsunami.
 This building is Economic Dedicated center. So, this is economical building, so this
“A” place is very suitable for this building, because this place is near the main street,
so, this place must have business value.
B – RESIDENTIAL BUILDING
 This place “B” is not a main site, not a
beach site, this is center of location.
So, this building is Residential
building, to this building very suitable
place is center of the location “B”
place,
 Because, this place is a center of the
location, so in this place peoples are
already living. In this place should be
have water supply and electricity
facilities also, because in this place already peoples are living.
 To this “B” place low cost compared with “A” place
 This place “B” is safety place. The place is protected from natural disasters and big
accident. Because, this is center of the location.
C – GROUND STADIUM
 This Place is beach site. Cost is very low, so
it is suitable for ground stadium
 This place have drainage facilities
 This place is Public Acceptance for ground
stadium

1.2 DESCRIBE THE STAGES IN SITE INVESTIGATION TO
INTENDED PROJECT SCHEME.
There are 05 stages in site investigation:
1. Desk Study
2. Site Reconnaissance
3. Exploratory Investigation
4. Laboratory testing
5. Report
DESK STUDY
Desk study is the first part of site investigation.
 Its means collecting older and newer details of proposed site such as
 Previous investigation reports
 Geological or historical maps
 Topographic maps
 Survey maps
 Current planning applications in the area
 Utilities (Location of services)
 Aerial photographs
We can get that information from Pradesha Sabha, Surveyor Department, Geological
Department, Agriculture Department, Mining Companies, Organizations performing soil, and
Geological studies.

SITE RECONNAISSANCE
Site inspection:
 This is means going over the site and surrounding areas. Important evidence to look
for is hydrology, slope instability, mining, access to site etc…
 The observations will give idea about structure and texture of soil, cross-section of
formation, ground water condition etc…
Arial reconnaissance:
 Main features like general topography, drainage, erosion, soil pattern and texture can
be examined closely from the air.
 Photographs can be taken for subsequent detailed study
Geological methods
 These methods are used to locate the boundaries between different
 It does not produce the properties of the strata.
 They need supplementation by other methods.
EXPLORATORY INVESTIGATION
 In this method we get knowledge information of the soil conditions. We get data
about soil condition at our site. For example
 What type soil, depth, thickness of soil, location of rock, location of water table etc.
Can be obtained.
 We mainly use two methods of site explorations, they are as follows:
o Open trial pits
o Boring (Auger boring, Wash boring, Percussion boring, Rotary boring).

01. Open trial pits
 Trial pits are shallow excavations going down to a depth no greater 6m. The trial pit
as such is used extensively at the surface for block sampling and detection of services
prior to borehole excavation.
DEPTH EXCAVATION METHOD
0.2 m By hand
2-4m Wheeled back hoe
4-6m Hydraulic Excavator
Table 01
 An important safety point to note is that ALL pits below a depth of 1.2m must be
supported. In addition care should be taken as gases such as methane and carbon
dioxide can build up in a trial pit. Breathing tools must therefore be used if no gas
detection equipment is available.
02. Boring
In this process, bore holes are made in the ground and the soil samples collected. Boring
helps in obtaining
 Extent of each strata of soil/rock
 Nature of each stratum and the engineering properties of the soils
 Location of ground water table.
The depth and number of boreholes will depend upon the type of the structure and nature of
the soil as obtained from preliminary examination. The depth of boreholes is governed by the
depth of the soil affected by the loading. As a rough estimate, it is advisable to investigate the
subsoil to a depth of at least twice the width of the anticipated largest size of the foundation.
In case of a pile foundation, the depth of boring should extend into the bearing stratum.

LABORATRY TESTING
 We get a our site soil, and we will got lab, there we test that soil.
 We get a knowledge what type soils have in that site.
 We finished this test we get a idea, what type of foundation suitable to this building.
Final Report:
All the basic record almost every geotechnical exploration and provides a detailed record of
the work performed and the findings of the investigation. The report should be written or
printed legibly, and should be kept as clean as practical. All appropriate portions of the report
should be completed in the field prior to completion of the field exploration.

1.3 EXPLAIN THE CLASSIFICATION OF SOIL AND DESCRIBE THE
SOIL INVESTIGATION METHODS TO SELECT SITE
LOCATION.
SOIL CLASSIFICATION
Very
coarse
soil
BOULDERS > 200 mm
COBBLES 60 - 200 mm
Coarse
soil
G
GRAVEL
coarse 20 - 60 mm
medium 6 - 20 mm
fine 2 - 6 mm
S
SAND
coarse 0.6 - 2.0 mm
medium 0.2 - 0.6 mm
fine 0.06 - 0.2 mm
Fine soil
M
SILT
coarse 0.02 - 0.06 mm
medium 0.006 - 0.02 mm
fine 0.002 - 0.006 mm
C CLAY <0.002 mm
Clay is sticky and plastic-like to handle when wet. The individual particles are extremely
small and can only be seen with the aid of an electron microscope. Silt is smooth and slippery
to the touch when wet and the individual particles are much smaller than those of sand. These
individual particles can only be seen with the aid of a microscope. Sand is gritty to the touch
and the individual grains or particles can be seen with the naked eye.
Soil is said to be well-graded if it is composed of a wide spectrum of grain size. Well-graded
soils typically have the best engineering properties.
The best soil are well-graded soil containing grave and sand (coarse material have the
greatest shear strength), but also silt to fill in the large void spaces and clay to add cohesion.

SOIL AT OUR SITES
This section briefly describes the soil condition encountered at site detailed soil condition are
presented in each log of boring in the Annexes of bore hole logs based on the data collected
from 3 number of boreholes, it can be classified the soil layer as follows;
I. Top soil
II. Sabkha soil
III. Marine soil
IV. Residual soil
V. Lime stone(highly weathered)
VI. Lime stone(slightly weathered)
TOP SOIL
From the surface to the depth of 0-0.5m was filled with top soil such as brown silty
sand with limestone
SABKHA SOIL
This soil type can be found in only BH-A borehole. The layer consist of light grey to
light brown poorly graded sand. Thickness is about 0.5m-3.5m and SPT consist medium
dense.
MARINE SAND
This soil type can be found only at BH-A borehole. The layer consist light grey to
light brown poorly graded sand. Thickness is about 3.5-8m and SPT loose to medium
LIME STONE (HIGHLY WEATHERED)
This stone can be found in BH-B borehole log. The layer consists of light green,
moderately week to moderately strong limestone. The RQD value 20-55%.

LIME STONE (SLIGHTLY WEATHERED)
This stone was encountered in borehole BH-B at depth 0-10m below ground level
until end of borehole. The stone is strong, light green and reddish pink. Clay and silty
material. RQD value 80-95%.
RESIDUAL SOIL
This soil type can be found in borehole BH-C. The layer consist brown silty sand.
Thickness is ranging about 0-0.3m.
SOIL INVESTIGATION METHOD
Soil Investigation is carried out for designing a right type of foundation safely and
economically, a designer must possess sufficient information about the physical properties
and the arrangement of underlying materials. The field and laboratory investigations required
to get this essential information is known as soil exploration. The study of complete soil
investigations can be grouped under the following heads,
The methods of soil investigations are:
 Inspection
 Test pits
 Probing
 Boring
 Methods of site exploration.
 Choice of a method
 Recording of data
The different methods of boring are:
1. Rotary wash Boring
2. Auger Boring
3. Core Drilling

Rotary wash Boring
Wash boring is commonly used for boring in
difficult soil. The hole is advanced by an auger
and then a casing pipe is pushed to prevent the
sides from caving in. A stream of water under
pressure is forced through the rod into the hole.
The loosened soil in suspension in water is collected in a tub.
In our site A- Economical dedicated center, B – Residential Building, C- Ground Stadium
Commonly we use Rotary wash boring.
This type of boring had been selected.
Because we select this type boring,
 It can be used in borings of both small and lager diameter.
 It can be used in most common soil, not containing numerous stones or boulders.
 The equipment is inexpensive and light.
 It doesn’t obstruct ground water observation as it doesn’t cause sealing of the bottom
of the hole.
Procedure
I. Rotary Boring Machine - can come in spindle type or top drive type. Most common is
spindle type. Able to carry out rotary action and or percussion action. Can be crawler
mounted or skid mounted
II. Drilling Pump - normally a single piston water pump used to circulate water to wash
out cuttings and cool the drill bit and drill rods
III. Water Supply Pump - used to supply water from water source to drilling locations if
location is not above water or very close to water. Uses delivery hoses
IV. Drill casings and rods for drilling and testing.
V. Testing equipment such as SPT, Vane Shears, and Permeability.
VI. Sampling equipment such as sampling tubes, undisturbed sampling tubes, maizer
samplers, piston samplers.

TASK-02
2.1DESCRIBEDIFFERENT TYPES OF FOUNDATION AND DISCUSS
VARIOUS FACTORS CONSIDERED IN SELECTING A SUITABLE
FOUNDATION FOR INTENDED PROJECT SCHEME.
Foundation is the main part of building. It is bear whole load of the building. That’s why we
should care about the foundation.
Foundation are classified in two main categories
1. Shallow foundation
2. Deep foundation
Shallow foundation
It is also known as Open foundation. Shallow foundation is placed in the lowest part of the
super structure. This foundation is spread the loads over a wider horizontal area at shallow
depth below the ground level.
Shallow foundation divided in 2 types
a. Spread footing foundation
It is also known as a footer or footing. The base of the foundation spreading
the loads to the soil is made wider so that load of the structure is issued on
sufficient area of the soil.

Spread footing divided in 3 types
i. Strip footing:
It is also known as a continuous spread footing.
It consist of a continuous strip, under walls. This strips made by
concrete footing which is normally widened and rest on the foundation
bed. Under wall rises from the foundation to a location somewhere
above the ground. The wall constructed by either brick or wall.
ii. Pad footing:
It is also known as rectangular spread footing and square spread
footing. It is generally in rectangular or square shape.
It has a slab of uniform thickness.
iii. Combined footing:
It is support more than one column and it is longer than pad footing. A
common footing provided for two or more column.
It is rectangular or trapezoidal shape.
If two columns come too close we can use it also if the column at or
near the property line we can use it.
b. Mat or raft foundation
It is large continuous footing. It is thick concrete slab reinforced with steels
and its cover the all contact area of the structure. It is normally build in marshy land,
soft clay and sanitary land. Mat-slab foundation can be constructed near the ground
surface, or at the bottom of basements.
There is some type of raft foundation
 Slab and beam Raft foundation – If the soil condition is bad we can use this type
foundation. The slab and beam provides stiffness.
 Down-stand beam raft foundation – It is used in stiff clay sites. There are
some advantages in this foundation such as it provides a level surface slab

which can form the ground floor of the building and it is saving excavation
cost. Here the column must be positioned at the inter section of the beams.
 Up-stand beam raft foundation – It is involves wide earthworks. It has to be
excavated and back filled. Here also the column must be positioned at the
intersection of the beams.
 Cellular raft foundation – It is suitable for poor soil is encountered at a
shallow depth. It is uneconomical than slab and beam raft foundation. Cellular
raft foundation has two reinforced concrete slabs connected by internal walls.
Deep Foundation
If the bearing capacity of the soil is weak we have to put deep foundation. Deep foundations are
needed to transfer loads from a structure through weak compressible soils or fills on to
tougher and fewer compressible soils or rocks at depth. These foundations are those founding
too deeply below the finished ground surface. This is usually at depths greater than 3 m below
finished ground level. Deep foundations can be used to spread the loading to more distance.
Deep foundation is divided in two categories;
1 Pile foundation:
If constructors are needed to put deep foundation they mostly used pile foundation.
Piles are like column. It is made by concrete, steel and timber. It is fixed in the ground
to transfer the structural loads to soils at some significant depth below the base of the
structure.
Piles foundation used in many situations such as;
 If the load is so high.
 If the soil condition is the weakest.
 If difficult to excavate the land.
 If the ground floor slabs has to be carried above the ground.

The expected settlement of the soil beats tolerable limits. Pile foundations are classified by
method of installation and method of load transmission.
2 Caisson foundation:
Caisson foundation is also called as pier foundation. It is look like a cylinder or
hollow box. The cylinder or hollow box is sunk into the ground to a depth by auguring
a deep hole into the strata. Then the cylinder or box is back filled with concrete. This
type of foundation is mostly used in bridge construction. It is the strongest foundation.
It can carry huge amount of load, the weight of the structure can be easily handled by
the piers and it is very strong.
Caisson foundation will decrease vibrations and has slightly less noise
 Our site has pad footing beam. When we select a suitable foundation we have to
considered following factors;
o Bearing capacity of the soil.
o Soil condition.
o Whole load of the building.
o Water level.
o Distance from the property line.
 We have three building, so we was select suitable foundation
 Economic Dedicated Center – Pile Foundation
 Residential Building – Stripe Foundation
 Ground Stadium - Raft Foundation

Economic Dedicated Center – Pile Foundation
Pile Foundation: This is one of the deep foundation types.
Pile foundation:
Piles are fairly long and small members used to transmit foundation loads through soil
strata of low bearing capacity to deeper soil to rock strata having a high bearing capacity.
They are also used in normal ground conditions to resist heavy uplift forces or in poor
soil condition to resist horizontal loads piles are convenient methods of foundation
construction for works over water such as jetties or bridges piers.
Following factors we had to consider in selecting a Pile Foundation at building to
Economic dedicated center
 Soil Type: Marine sand, Loose to medium dense, light grey to light brown, poorly
graded sand.
 Building design: This is a 10 stories building.
 Piling plant and equipment available: All equipment’s are have in this site.
 Cost for the foundation: cost for this foundation is high but strong is very good.
 Commonly we use to high story buildings PILE Foundation. So, this Economic
dedicated center is 10 story. So this foundation is suitable for Economic dedicated
center
Residential Building – Stripe Foundation

These are suitable for most subsoil’s and light structural loadings such as those encountered
in low to medium rise domestic dwelling where mass concrete can be used. Reinforced
concrete is usually required for all other situations.
Following factors we had to consider in selecting a Stripe Foundation to Residential Building
 Soil Type: Moderately weak to moderately strong off white to creamy, moderately to
slightly weathered and fractured micro-crystalline limestone with inclusions of light
green and reddish pink clay (10-15%) and silty materials.
 Building design: This is a 2 stories Residential Building.
 So, this is light structural load building, so this foundation is suitable for the
Residential Building.
Ground Stadium - Raft Foundation
These are used spread the load of the substructure over a large base reduces the load per unit
area being imposed on the ground and this particularly useful where low bearing capacity
soils are encountered and where individual Colum load are heavy.
Following factors we had to consider in selecting Raft Foundation at building Ground
stadium
 Soil Type : Moderately weak to moderately strong off white to creamy, moderately to
slightly weathered and fractured limestone with inclusions of light green attapulgitic
(15-25%) and silty materials.
 Building design: This is a 4 stories ground stadium
 The site, the environment (the buildings nearby): Right site is sea, left site- main road
site.
 Cost for the foundation: normal cost this foundation and same time strong is good

2.2 DESCRIBETHE METHOD OF EXCAVATION SUITABLE FOR
THE SELECTED FOUNDATIONS WORK AND ASSOCIATED
TEMPORARY WORK FOR YOUR INTEND PROJECT.
Excavation
To remove the top soil or dig a hole in the ground which is to be built upon is known as
excavation. The reason for this is that the top layer of the ground contains material which is
decomposing along with active plant life in the form of grass, flowers, roots or shrubs, etc.
this material is easily compressible and as such is unsuitable for foundation.
Excavation means removal of earth for making foundation or basement or other purposes.
There are several types of excavation in construction.
 Soil strip
 Reduced level excavation
 Bulk excavation
 Trench excavation
 Hole or Pit excavation
These excavations can be done by back co, bulldozer, scraper, and shovel
Soil Strip:
By this method, the vegetable soil must be removed before any other excavation takes place.
The process is to strip the surface of the ground of its topsoil covering. These are achieved by
the use of certain type of machinery.
Reduced Level Excavation:
On a sloping site, it may be necessary to cut into the banking on one side of the proposed
building, while filling with suitable material on the other side, in order to achieve the level
working surface of formation level

Bulk Excavation:
If we have to be excavated large volume of soil
we want to use bulk excavation in order to
achieve the formation level. It can be perform as
a reduce level or to provide basement areas. We
can use excavator or bulldozer for bulk excavation.
Trench Excavation:
If a site has bulk excavation or soil strip excavation we have to start trench excavation after
finished the bulk or soil strip excavation.
The purpose of trench excavation is making
foundation and theirs temporary supporting
system. We can do it manually or using backhoe.
If there is considerable width, excavator also can
be used.
Hole or Pit Excavation:
The design of the substructure may require pits to be excavated. In the case of circular holes,
hand or mechanically driven augers or drills are used. Pits, being small shallow or rectangular
holes, may be excavated mechanically or by hand.

 If we excavated heavy volume soil we select bulk excavation. The purpose of bulk
excavation to provide basement areas. There was a floor part and foundation of older
building that’s why they have selected bulk excavation and they have used bulldozer
for excavate.
EXCAVATION SUPPORTING SYSTEM
The supporting system could be done in 03 ways, they are;
 Cantilever: The cantilever method relies entirely on the passive resistance of the soil
below the excavation line to support the excavation active load and live loads. The
cantilever method is the simplest from a construction standpoint.
 Braced: The braced system uses internal bracing and the embedded pile to share the
support of the excavation active pressure and surcharge loads.
 Box: The box system relies entirely on the internal bracing to resist the excavation
active and live load forces. This shoring system can often be designed to be very
efficient structurally.

2.3 IDENTIFY THE STEPS IN THE PROCESS OF
CONSTRUCTING THE SELECTED FOUNDATIONS.
A - Economic Dedicated Center – Pile Foundation
The pile foundation process starts off much the same as any other foundation
work. Firstly the site will be properly excavated; this involves removing the first 150mm
of soil and debris. The area is then deepened and removed of any contaminates to leave a
good working base before the ground is marked to clearly show where the piles need to
be placed.
There are two main ways the piles can be placed in the ground:
1. Driven
Driving piles into the
ground requires the use of a large
machine which acts very much like
a hammer. The machine forces the
piles into the ground to the depth
needed. The piles are normally 3m lengths and are either made of pre-cast reinforced
concrete or steel.
2. Augured
The auguring process uses a large drilling machine which drills holes to the
required depth before concrete is poured into the tube that is currently filling the hole.
The tube is then carefully removed as the drilled holes fill with concrete. Tubular
framework is then placed into the concrete to reinforce the piles.
After this process has been completed pile caps are then placed on top of the
piles, providing a platform for the surface foundation.

C – Ground Stadium –Raft Foundation
 The whole area is dug out to the specified depth and 30 cm more wide than the area to
be covered.
 The bed is compacted and sprinkled over with water.
 Then a layer of lime concrete or lean concrete (1: 8: 16) is laid to a suitable thickness
to act as a bottom cover.
 After this, the reinforcement is laid. The reinforcement consists of closely spaced bars
placed at right angles to one another.
 Then the cement concrete (1: 2: 4) is laid and compacted to the required thickness.
 The concrete slab so laid is
then properly cured.
 When loads are excessive,
thick concrete beams running
under the columns can also be
constructed.

TASK-03
3.1 IDENTIFY AND DISCUSS THE FORM WORK NEEDED FOR
THE CONSTRUCTION OF BUILDING ELEMENTS AND THEIR
SUPPORTING FOR THE RESIDENTIAL BUILDING.
FORM WORK:
As a definition, Formwork is an ancillary construction, used as a mould for a
structure. Into this mould, fresh concrete is placed only to harden subsequently.
Shutters or forms are the terms used for made up sections that actually touch the
concrete. The surface finish of the form is reflected on the surface of the finished
concrete.
Good formwork should satisfy the following requirements:
 It should be strong enough to withstand all types of dead and live loads.
 It should be rigidly constructed and efficiently propped and braced both horizontally
and vertically, so as to retain its shape.
 The joints in the formwork should be water-tight against leakage of cement grout.
 Erection of formwork should permit removal of various parts in desired sequences
without damage to the concrete.
 The material of the formwork should be cheap, easily available and should be suitable
for reuse.
 The formwork should be set accurately to the desired line and levels. It should
have plane surface.
 It should be as light as possible.
 The material of the formwork should not warp or get distorted when exposed to the
elements.
 It should rest on firm base.
FALSE WORK:

False work means any temporary structure that is used to support a permanent
structure, material, plant, equipment and personnel until the construction of the permanent
structure has advanced to the stage that it is self-supporting.
 A temporary structural support system referred to as false work includes the
foundations, footings and all structural members supporting the permanent structural
elements.
 False work is commonly used to support spanning or arched structures, such as
bridges, while they are being constructed.
 The temporary support structures for formwork (see above) used to mould concrete to
form a desired shape and the scaffolding that might also give workers access to the
structure being constructed is sometimes referred to as false work.
 Formwork can be made by using timber, steel or aluminum.
MATERIALS FOR MWORK:
Formwork can be made out of timber, plywood, steel, precast concrete or
fiber glass used separately or in combination. Steel forms are used in situation where
large numbers of re-use of the same forms are anticipated. For small works, timber
formwork proves useful. Fiber glass made of precast concrete and aluminum are
used in cast-in-situ construction such as slabs or members involving curved surfaces.
 Timber Formwork:
 Steel Formwork
 Plywood Formwork
 Plastic Formwork
 Corrugated & Flat Permanent Formwork
TYPES OF FORMWORK:
 Foundation Formwork
 Wall Formwork
 Ceiling Formwork
 Beam Formwork
 Column Formwork

Supporting System For The Residential Building
FORMWORK FOR COLUMN:
Column formwork includes 3 main parts such as:
1 Sheathing – Timber which is build up all along the
perimeter of the formwork.
2 Yokes – It is classified in to 2 categories such as
side yokes and end yokes. It is properly spaced all along to the length of formwork.
3 Wedges – The use of wedges is tightening various elements of the work.
4 Supports - It has supports too. Normally column formwork has 4 numbers of supports at
every side.
If we finished the column form work we have to check the following things
 Vertical alignment
 Size of the column
 Angle between faces
 Proper supporting
 Any possible leakages
 Internal surface area smooth or not
FORMWORK FOR BEAM:
It is in correct level at correct position like a three sided box. There are 2 types of beams such
as Tee beam and L beam that’s we have to fixed the beam formwork in 2 ways.

Beam Formwork has 2 parts
 Soffit board
 Side boards
After finish the formwork for beam we have to check these
 Level of beam bottom.
 Any possible leakages.
 Width and depth of beam.
 Smoothness of the inner surface of the formwork.
 Proper supporting.
FORMWORK FOR SLAB:
It is consist…
 Soffit board
 Side board
 Supports
It is likewise beam formwork but soffit board is larger than beam formwork. The end of slab
formwork, we need to check the following things;
 Level of slab-using a leveling instrument.
 Any possible leakage.
 Alignment and proper supports of the slab sideboards.
 Smoothness of the top surface of the formwork.
 Proper supporting.
Slab formwork has large number of supports more than column formwork.

FORMWORK FOR STAIRCASE:
Staircase is connected from ground floor to first floor or from one floor to
another floor. Form work of staircases contains
 Planks
 Plank connectors
 Skirting board
 Soffit board
 Supports

3.2 EXPLAIN THE REINFORCEMENT ARRANGEMENTOF IN-
SITU CONCRETEMEMBERS.
Introduction
Any material specified for use as a reinforce member. But the following factors are needed
for construct a good building element.
At the site according to the engineer drawing strip footing foundation, beams, columns,
slabs and stair case are constructed with use of reinforcement.
The reinforcement bars arrangement we should check all these things
1. Bar spacing
2. Cover
3. Tying Requirements
4. Notation of the reinforcement bars
Bar Spacing
Placing drawings are using to show where the reinforcing bars to be placed sometime the
structural and placing drawings are very specific about exactly where rebar is placed.
The ironworks need to figure out how those rebar’s relate to the overall dimension of the
structure.
Cover
Cover blocks are placed to prevent the steel rods from rusting due to exposure to air, and to
fix the bars in place.
Sometimes during the concreting activity, the covers tend to get displaced.

To prevent this, tie the cover block using thin steel wires called binding wires to the steel
bars. The blocks could be cubical or cylindrical in shape. Normally, cubical cover blocks are
used.
A minimum cover 1.5" in columns and half inch to three-fourths inch for slabs and beams is
recommended.
Notation Of The Reinforcement Bars
17Y10-103-100T which can be translated as:-
 17– No. of bars
 Y – Steel type.
 10 –Diameter of the bar
 103- bar mark
 100-spacing in mm
 T-top reinforcement (B-bottom)
Concrete structures are very important elements in a building construction. Those are:
 Column
 Beam
 Slab
 Staircases
Column reinforcement
The function of the column is to transfer the loads from beams to the foundation safety.
The column when supporting a weight is under compression. Failure in a column will depend
on:
 The material from which it is made and the stress that material can take.

Method of construction of the column
1. From the foundation (whatever type either pad or strip or raft) extension of the
reinforcement for the column will be kept as lapping length or full size of an available
reinforcement member.
2. Kicker box would be set at the dimension of the column and it would be cast at a height
of 2’’ to keep the column box in position.
3. Re-bar arrangements- the stirrups and cover blocks would be tied up with main bars
4. Formwork of the columns will be fixed either form of iron boxes or wooden boxes and it
would be supported by props and the verticality would be checked by using plumb bob
and alignment of the columns checked by theodolite.
5. The height of the concrete kept not more than 5’at once to avoid unnecessary effects on
concrete
6. Leave 24 hours to harden and rest of the part will be continued up to requited level.
7. Curing
Beam reinforcement
1. Beams which support walls and floors may
be designed in a similar manner to floor
slabs. E.g. Simple, restrained, continuous,
and cantilever.
2. Each method of design imposed a vertical of loading and bending condition upon the
beam but in essence the forces are compression tension and shear.
3. The main reinforcement is designed to carry the maximum bending movement but as
that movement change for different positions on the beam, the requirement for
reinforcement is also changed.
4. Where the movement is reduced E.g. In the case of continuous or restrained beams,
the tension zone changes from the bottom to top of a beam in the region of the
support.
5. Hence reinforcement can be seen changing from one face to the other and at the same
time, during that transition, being used to provided additional shear resistance further
shear resistance is provided by vertical links or stirrups (similar to the bending in a
column).
6. Also provide against shrinkage cracking.

7. The spacing of these links must be designed, because the share force on a beam is
changing from a minimum value around the mid span region to maximum at the
supports. Hence the links are generally closer together rear the support than they are
at mid span.
Slab reinforcement
A reinforced concrete slab will behave in exactly the same manners as a reinforced concrete
beam and it is therefore designed in the same manner.
The designer will analyze the loading bending movement shear force and reinforcement
requirements also a slab strip 1M wide. In practice the reinforcement will be fabricated to
form a continuous mat for light loading a mat
of welded fabric could be used.
Beam and slab
By adopting the method of design large spans
are possible and the reinforcement is
generally uncompleted. A reinforcement; as
with the flat slabs this can be provided by
cracked bars. Each bar is in flat cracked but alternate bar are reversed thus simplifying
bending and identification of the bars. Alternative a separate mat of reinforcement supported
or chairs can be used in the supports
Stair case reinforcement
This reinforcement is different type. Also it is different with type of stair case. Flights of stair
case are similar with floor slab. Reinforcement of stair case is similar with slab net. Here
important point is junction of flight – landing.
 Bottom reinforcement of flight is connected with top reinforcement of landing.
 Bottom reinforcement of landing is connected with top reinforcement of flight.

STAIR CASE REINFORCEMENT CHECK
1. Check bottom reinforcement (main bar, distribution bar)
 Diameter of bar
 Type of bar
2. Check top reinforcement same as above
3. Check the interconnection of top – bottom at junction.
Usual reinforcement for stair case is Y10.
BAR CUTTING & BENDING
 To cut the steel bars many mechanical systems are used. Among these methods,
electrical power supplied metal bar cutting machines are used in our site.
 In our site we used bar bending by hand. It is very hard full our work for dong with
delay.
 Also bar bending works are done at the site.

3.6DISCUSS THE BLOCK WORK CONSTRUCTION IN THE
RESIDENTIAL BUILDING & ECONOMIC DEDICATED
CENTRE.
Brick are not all exactly the same size or shape. The mortar joints in brick work
accommodate slight difference in size and allow the brick work to look neat and tide by
keeping the top aria flat and level
Good brick wall following resources
1. Materials
2. Equipment / tools
MATERIALS
Brick
 These materials are come in slightly different shapes and sizes owing to the variation
in the firing process when the bricks are manufactured when in the kiln, bricks closer
to the heat source tend to and up slightly smaller and darker.
 When the transporting time also there may be some damages. Because of this
damages bricks size vary to each other.
Mortar
 Mortar can be either a mixture of sand and lime or a mixture of sand and cement with
or with is contain cement. Common mixtures are at a ratio of 1: 3 (cement: sand) or
1:1:6 (cement: lime: sand) and water also added to these materials.
 It is important that mortar stays workable long enough for brick to be laid but it
should really be used within two hours of mixing. Batches of mortar mixed should be
relatively small, as any mortar that starts to set before use has to be thrown away.

Mortar has very important part to play in the construction of buildings as it is the mortar that
transfers the stresses uniformly through the brick work. If the mortar is not as strong as the
bricks cracks can appear along the joint of the bricks.
EQUIPMENT / TOOLS
Brick Trowel
The main tool used by the bricklayer. Also known as a wall trowel. Used to roll and spread
mortar to form a uniform bed joint and to apply mortar to cross joint. This is sometimes
known as buttering the brick. It has a hardened edge, so an experience brick layer can use it
to cut brick.
Hawk
Used to hold small quantity of stiff mortar when filling joints and jointing. In new work
where joint only need joint finish applying, the bricklayer may use the flat blade to hold
mortar for occasional joints needing filling.
Brick bond
The different pattern of the bricks in a wall is known as brick bonding. Used of tool and
process bricklayers laying the brickwork. When bricklayers keeping the brick, bond can be
varies. There are several types of brick bonds.
Types of bond
 Stretcher bond
 English bond
 Header bond
 Flemish bond
 Herringbone bond

English bond
English bond is made up of alternative courses of headers and stretchers. This produces a
solid wall that is a full brick in depth. English bond is fairly easy to lay and is the stronger
bond for a one brick thick wall.
Flemish bond
This bond is known as Dutch bond, and it has historically always been considered the most
decorative bond. And for this reason was used extensively for dwelling until the adopted of
the cavity wall. It is created by alternately laying headers and stretchers in a single of course.
The next course is laid so that a header lies in the middle of the stretcher in the course blow.
This type of wall having one brick thickness.
Stretcher bond
Stretcher bond is the easiest to construct with little waste. Entirely comprised of stretcher
bricks (or “courses”) that are offset by half a brick.
Header bond
Header bond (known as Spanish bond) was a very common bond for bearing walls. It is
composed of header bricks, set in rows that are offset half a brick, which produces a solid
easy to lay bond which is useful when building circular work. It is the most used bond in
historical Spanish bond construction.
Herring born bond
When bricks are laid on alternating angles, it is called a Herringbone. This is primarily a
decorative style, more often used for paving or fireplace reflectors than for walls. It is
generally considered unsuitable for load-bearing structures, but may be found as infill in
traditional timber framed buildings. This style is also sometimes called by its Latin name:
Opus spicatum.

While constructing brick masonry there is few things which are important to take in
consideration. They are
 Brick should be properly soaked in water before the erection wall is started. This is
done so that the bonding between the brick and mortar will be strong.
 The brick should be laid so that the frog of the brick will face upwards.
 Mortar using for the masonry work should be stiff like rubber.
 The vertical joint of alternative courses should not come under one line. If this
happens then the bonding will not be strong and it will end up in a failure.
 The walls should be raised uniformly and vertically and this should be tested in very
course. And the thickness of all the joints should be same and it should not exceed
than the standard thickness size.
 The wall should not be completed with one day the maximum height should not
exceed than1.5m and the masonry work should be kept wet from 4 to 7 days to allow
the mortar to set properly so that the bonds will be strong.
 Subject: Brick walls
 Type: Internal partition wall
 External perimeter wall
 Specification: English bond – Partition wall
 Stretcher bond – External wall
 Cement and sand ratio of mortar 1:5
 Materials: Bricks, Cement, Sand, Water
Normally in the building construction in Sri Lanka English bond is famous. So with the use
of three main resources (man, materials, and tools) brick bond was done at the site. Materials
mortar (cement sand ratio 1:3) and bricks these two materials are in high quality that provide
a good brick wall. Men means the brick layer, the person was having the experience and he
was had the patient also

3.7DESCRIBE THE FOLLOWING WORK FOR PLASTERING
OF EXTERNALAND INTERNALWALL AND THE WORK IN
RESIDENTIAL BUILDING/ECONOMIC DEDICATED
CENTRE.
Introduction
The art of covering the surface of the masonry work with a suitable plaster is called
plastering. There are different types of plastering work used for the construction industry.
Normally in the wall finishing cement plastering work was used in the construction industry
Finishes
It is required to cover up irregularities in the background and to provide a finish that is
smooth, crack-free, hygienic and resistant to damage and easily decorated. It may also be
required to improve fire resistance to provide additional thermal and sound insulation, to
modify sound absorption or mitigate the effects of condensation.
Generally, finishes should provide for a building to provide good appearance and protect
from other factors, such as fire, rainy, sun.
Wall finishes
When we do the finishing work for wall we have to do the following works. Some of them
are not significant. But it will give us good appearance.
 Plastering
 Tiling
 Painting
In selected site, they have done the plastering by using mortar.
Plastering gives more strength to the wall.

Plastering
Plasters usually contain a binding materials, fine aggregates and water. Plastering of walls
were done with cement sand motor in 1:5 preparation to 15 mm thickness. The plaster used
was a lime plaster which generally has been superseded by gypsum plasters. Lime plastering
unlike therefore more disadvantages include.
The actual mix chosen will depend upon the class of plaster used and the properties of the
background material. Cement backing to plasters usually have a volume mix of 1:1:6 -
cement: lime: sand, whereas finishing plaster coats can be applied neat or with up to 25%
slaked lime putty by volume. The main purposes of plastering are;
 To get an even smooth surface
 Regular surface
 Durable surface
 To protect the surface of the wall from the effect of atmospheric influence.
 Weather problems
Types of plasters
 Lime plaster
 Cement & lime plaster
 Gypsum plaster
 Surface for plastering
 Defects in plastering
Wall tiling
Normally we place the tile for walls and floors. Normal size of the marbles is
 4 ¼” × 4 ¼”
 6” × 6”
 8” × 8”

Thickness of the marble is usually 6 mm. bathroom fittings need specially shaped tiles made
to negotiate internal and external corners.
Procedure of tile laying
 A rendering of cement: sand = 1:3 mortars applied over the proposed surface of walls.
 The rendering finished with wood floats to give an even texture.
 The surface left scratched by wire nail for the bonding mortar.
 The rendering cured for a week and allowed to dry.
 The rendering applied at least two weeks old before the tiles are fixed.
 External tiling started from top and worked downwards.
 Before fixing tiles, rendering allowed to dry.
 Tiles soaked into the water at least half an hour and then drained and stacked.
Painting
Paint consists essentially of a pigment, a binder and a solvent or thinner to make the mixture
suitable for application by brush, roller or spray. After application, the paint undergoes
changes which convert it from a fluid to a tough film which binds the pigment. The nature of
these changes varies with different types of paint.
Paint and brush
Materials used in the painting of building fall into three main categories
 Pigmented coatings, such as paints and wood stains.
 Clear coating such as varnishes and lacquers.
 Ancillary materials, such as fillers, stoppers and other materials used in the
preparation of surfaces.

Painting walls
Walls may be painted to provide color or surface texture, to waterproof them, to reflect of
absorb light and to facilitate cleaning and hygiene. Matt finishes are often preferred because
they avoid reflection of light sources and minimize surfaces irregularities. Gloss finishes
provide maximum wash ability and exterior durability.
Emulsion paint typically based on vinyl or acrylic polymers, is very suitable for application
to walls and ceilings but normally avoiding impervious surfaces, kitchens and bathrooms and
is better able to withstand scrubbing and weathering.
The purposes of painting are given below,
 Plaster surface protect from rain and sunlight.
 To provide attractive appearance.

3.8IDENTIFY THE ELEMENTS TO BE WATER PROOFED IN
THE RESIDENTIAL BUILDING AND ECONOMIC
DEDICATED CENTRE AND EXPLAIN THE METHOD OF
WATER PROOFING FOR WASHROOMS & TOILET IN THE
BUILDING.
Waterproofing, this has an important role in any type of Construction works. The main
purpose of the waterproofing is to stop water penetration through solid surfaces. Normally the
waterproofing is considered when constructing
 Foundation
 Floor
 External wall
 Bathrooms & toilets
 Roof top slab
These are the building elements have the possibility to contact with water. Generally
waterproofing used on a wide variety of surfaces such concrete, brick, bitumen & mastic
asphalt membranes, asbestos cement slates, tiles, lead, copper Zinc, corrugated iron and
similar surface.
Damp proofing for foundation
Before dealing with the problem of dam-proofing treatment to be given to foundation, it is
necessary to have an idea about the ground water level.
When it rains, the rain water seeps through the ground until it is stopped by an impervious
layer in the sub-soil strata.

Damp proofing for walls
In external walls, horizontal D.P.C should be provided at 150mm to 200mm above ground
level. In this case, a vertical D.P.C is also provided on the inner face of the external wall from
the horizontal D.P.C to the ground floor topping. Horizontal D.P.C can also be provided at
plinth level and in that case no vertical D.P.C can also be provided at plinth level and in that
case no vertical D.P.C is required.
Water proofing for roof top slab
Flat slab roofs require relatively heavier and costlier water proofing treatment as compares
with pitched or sloped roofs. The specification of material used for the purpose should be
such that it performs the function of water proofing as well as provides adequate thermal
insulation. Stagnation of water on the roof is considered to be the roof cause of leakage and
dampness in flat roof slab. This can be avoiding by providing adequate roofs slope and rain
water pipe
Water proofing materials
The water proofing materials should have the following characteristics:
 The material should be perfectly impervious and it should not permit any moisture
penetration or travel through it.
 The material should be durable
 The material should be strong capable of resisting pressure on it.
 Material should be flexible so that it can accommodate the structural movements
without any fracture.
 The material should not be costly
 The material should remain steady in its position once applied.

FOLLOWING MATERIALS ARE COMMONLY USED FOR DAMP PROOFING
CAUSE:
Hot bitumen
This is highly flexible material, which can be applied with minimum thickness of 3mm.
Mastic asphalt
As defined in British Standard it is composed of suitability graded mineral matter and
asphaltic cement, in such proportions as to form a coherent, void less, impermeable mass
solid or semi-solid under normal temperature conditions, but sufficiently fluid when brought
to a suitable temperature to be spread by means of a hand float.

Bituminous or asphaltic felts
This is a flexible material which is available in
rolls. It is generally laid over on a leveled flat
layer of cement mortar
Polythene sheets
 There are two general methods of waterproofing.
 In positive side water proofing, the water proofing applied to the same side of wall or
floor on which the water source occur.
 In negative side water proofing, the water
proofing is applied on the opposite side of
the structure as the water source.
 Positive side water proofing is always
preferable because the structure itself is
protected from moisture penetration, as well
as the interior spaces.

WATER PROOFING FOR FOUNDATION AT SELECTED SITE
 It is absolutely necessary to waterproof the foundation of a building.
 Foundation waterproofing is a critical step in maintaining value of the building and an
important measure for preventing very serious damage.
 Usually done by professionals, there specialized contractors available in Colombo to
do perfect waterproofing.
 In generally foundation waterproofing is not recommended as a do-it-yourself project.
 But in the Hessonite building site as the found that the water table considerably lower
than the bottom of the foundation and no serious flooding or pooling of water during
the seasonal rain.
 So Hessonite engineers them done the waterproofing for the building.
 Basically the main idea is to isolate the building foundation from the contact of water.
WATER PROOFING FOR WASHROOM AND TOILET AT SELECTED SITE
 It is absolutely necessary to waterproof the Washroom and Toilet of a building.
 Washroom and toilet waterproofing is a critical step in maintaining value of the
building and an important measure for preventing very serious damage.
 Usually done by professionals, there specialized contractors available in Colombo to
do perfect waterproofing.
 In generally Washroom and toilet waterproofing is not recommended as a do-it-
yourself project.

3.9EXPLAIN AND WRITE METHOD STATEMENT FOR THE
METHOD OF CONSTRUCTION OF PRE-TENSIONED AND
POST-TENSIONED BEAMS IN ECONOMIC DEDICATED
CENTRE.
REINFORCED CONCRETE & PRE-STRESSED CONCRETE
 Both utilize the structural capabilities of steel and concrete. Concrete is very strong
in compression, but relatively weak in tension.
Ordinary Reinforced Concrete
 Beam supports a load by developing compressive stresses at the top, but since the
concrete cannot resist the tension at the bottom, it cracks there.
 Reinforcing steel bars are placed within this tension zone to resist the tension and
control the cracking.
Pre-stressed Concrete
 However involves the application of forced or forces tending to bend and compress a
concrete structure or structural element in ordered counteractive bending which
results from loading.
 The forced applied is the tensioning or stretching of the steel component which
usually in the form of high tensile strands, wires or bars.
Pre -tension
 The beams or elements are constructed on a stressing bed and stranded cable is placed
between two buttresses anchored to stressing bed which holds the force in the
stretched cable.

 After stretching the steel with hydraulic jacks, concrete is placed in forms around the
cables and allowed to harden. When the concrete reaches sufficient strength, the pre-
stress forced is transferred to the concrete by bond when the steel strand at the ends of
the beam is cut loose from buttresses.
Post-tensioned
 So called tendons (wire strand or cable) are placed in the forms at the proper location.
These tendons are covered with a multi-layer heavy paper wrapping.
 Concrete is then placed in the forms around the tendons and allowed to harden to the
required strength (usually 5 to 7 days).
 After the concrete has hardened, the pre-stressing steel which is separated from the
concrete by paper, plastic or metal sheathing is stressed or stretched by a hydraulic
jack which pushes directly against anchorage embedded in the hardened concrete.
 The force in the stretched steel is then permanently transferred to the concrete
through the anchorage devices at the end of the concrete casting.
 The use of curved tendons will help carry some of the shear in a member. In addition
pre-compression in concrete tends to reduce diagonal tension. Thus it is possible to
use a smaller section in post-tensioned concrete to carry the same amount of external
shear in a beam.
 Pre-tensioned pre-stressed concrete is usually fabricated away from the job site in a
pre-stressing plant, whereas in post-tensioned pre-stressed concrete the application
of stressing forces to the structure is done at the job-site.

3.10 DISCUSS THE METHOD OF JOINING AND INSTALLING
THE TIMBER WORK IN PREPARATION OF ROOF FOR
RESIDENTIAL BUILDING.
Building a Pitched Roof - Joining Method
One of the first stages of construction is fixing the wall plate. This is simply a timber beam
that is fixed to the top of all the walls (typically by nailing through it directly into the
brickwork below). Its purpose is to allow easy fixing of all further timber at the wall
interface.
A more modern enhancement to this technique
is to include metal straps that help tie the wall
plate to the walls. Typically these nail over the
wall plate and are then fixed to the inner
surface of the wall.
Once the wall plates are in place, the loft floor
/ ceiling joists can be placed. These are skew
nailed into the wall plates at each end, and
may also be nailed together where there meet on the central spine wall. In addition to making
a working platform for the remainder of the roof assembly, they also help resist the forces
applied by the rafters when loaded that would otherwise attempt to spread the supporting
walls.
The next timber to prepare is the ridge beam. This
serves as a joining place for all the rafters at the
top of the roof. With a symmetrical roof the forces
applied to either side of it from the rafters and the
weight of the tiles etc should balance, hence there
is no need for this to be a particularly substantial
timber. For roofs that will include large dormer

windows on one side it may be necessary to
make this stronger, or in some cases even
substituting a steel joist.
Once the ridge is ready, the first "pattern"
rafter can be cut. This will need to be
accurately measured and marked out with
the correct angles at both ends and the
position of the birdsmouth joint before cutting. Once the pattern has been produced all further
rafters can be cut from that template. This helps ensure that all the rafters are the same, and so
long as the final brickwork level of the house is plumb, the roof should be also. Typically an
end pair of rafters can be fixed in place at the base first, and then one end of the ridge inserted
between them and tacked in place.
Finally purlins are usually installed before
any significant loading is applied to the
rafters. These support the rafters typically
either at mid span, or possibly at 1/3rd and
2/3r span if used in a pair. The purlins
themselves are often fixed to gable end walls
when available - often resting on a small
projection of corbelled brickwork. In the absence of gable ends (or when additional support is
required) struts may be used to prop the purlin and transfer some of the load either to the
spine wall of the building or possibly to the loft floor.

Tiling a Roof
Once the mechanical structure is in place and
fixed, one can prepare the roof for tiling. The first
step is to fix the sarking. This is either a tiler's
felt (like normal roofing felt, but with a hessian
re-enforcement), or a breathable membrane like
Tyvek sheeting. This is fixed in strips starting at
the bottom. Each strip (typically a rolls width at
1.2m) should overlap the previous one by a few inches to ensure that any water that runs
down the sarking will not penetrate the roof space. Sarking is traditionally fixed either with
large head clout nails, or more commonly, ordinary wire nails hammered partially in, and
then bent over.
The sarking is usually left a little long at the facia end, so that it can overhang the facia, and
deposit any water on it directly into the gutter
After the sarking, the tile batten can be nailed on. Typically spaced evenly at 100mm
intervals, these not only provide a fixing and hanging location for the tiles, they also greatly
strengthen the roof and consolidate its structure.
A roof that it felted and battened is also basically waterproof - even without tiles.
The next job is tiling. Typically each tile has lugs that enable it to hang onto the tile batten. It
will also have nail holes to allow it to be nailed to the batten. Every other row ought to be
nailed on. However the actual level of fixing
will depend on the location and the likelihood of
extreme weather. It is not uncommon to find
roofs with very few if any tiles nailed in place

It is often easier to fix the facias before the first row of
tiles are installed. That way the facia can hold up the
bottom row of tiles at the same angle as subsequent
rows (that partially rest on the rows below).
The tiles are laid at the base of the roof first. The first
row may need to be shortened a little to prevent them
protruding beyond the facia board too far - ideally they want to drain into the middle of the
gutter. Subsequent rows are placed so as to overlay 2/3rds of the height of the tile, and half its
width (you need a 1.5x width tiles at the start of each alternate row to allow this). Tiles are
placed side by side, but (with plain flat tiles) small gaps can be left to maintain the aesthetic
spacing of the tiles. Modern interlocking tiles set their own gap spacings.
Once all the tiles are in place, the ridge tiles can be bedded onto a mortar mix, and the gaps
between them pointed. The exposed tile edges at the gable ends can also be pointed in.

CONCLUSION
Formwork is the most important part in the construction work. Regarding this task column
form work, beam form work, foundation slab form work and their supporting systems are
explained Reinforcement is most important part in the construction works, in this task the
reinforcement arrangement is mentioned.
Most of the buildings are built by bricks. In Sir Lanka brick is the most usable construction
material. Brick is stronger than other wall materials. In that site the finishes are not done yet. In
this report it includes some common details about the floor finishing.
In our site the water proofing work is not done yet. But the concrete slab roof is already built.
So here some common details are included. These are taken from one of the leading water
proofing company in Sri Lanka. Timber is a most usable material used in construction site.
It’s used in doors, windows, staircase, excavation work, joining, carpentries and formworks.

REFERENCES
 Bcas (2015). building construction technology. colombo: bcas. 03-04.
 DIYWiki. (2014). roof construction. Available:
http://wiki.diyfaq.org.uk/index.php?title=Roof_construction. Last accessed 23th jul
2015
 All images are got from Google image search engine.
 Bcas (2015). building construction technology. colombo: bcas. 03-04.
 castles. (2013). Step by step: How to build a Raft Foundation.Available:
http://www.castles.com.ng/articles-
story.aspx?id=2046&AspxAutoDetectCookieSupport=1. Last accessed 31st jan 2015.
 Chris van Hemer. (2010). trench. Available: http://www.trench.co.za/trenching.html.
Last accessed 23th jul 2015.
 Chudly, R. (1987). Constructions Technology. 2nd ed. Longman: SingaporePublishers
(pte) Ltd.. 1-200.

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