10.

0 WALL SYSTEM
10.1 Introduction
 Walls are the vertical constructions of a building that enclose, separate, and
protect its interior spaces.
 They may be loadbearing structures of homogeneous or composite construction
designed to support imposed loads from floors and roofs, or consist of a
framework of columns and beams with non-structural panels attached to or filling
in between them.
 There are two types of walls which are :
i. Exterior wall
ii. Inteior wall

10.2 Function of wall

 Support other parts of the structure such as upper floors and roof.
 Provide mutual stability with other building parts.
 Give privacy to the occupants from outside the house and between compartments
in the house
 Modify the micro-climate inside the building such as heat, temperature and
others.

10.3 Requirement of wall

Requirement Description
i. Structural  Resistance to overturning, crushing and buckling.
stability
ii. Dimensional  Thermally induced movement
stability
iii. Weather  Resistance to weather, air movement and fire.
resistance  Thermal resistance and termal capacity 
 Noise transmission
iv. Fire  Wall must not spread the fire easily. Requirement that
resistance need to compile in construction of windows are :
i. Combustibility : How easily a material will ignite and
sustain ignition 
ii. Surface spread of flame : the rate at which flame will
spread across one material to ignite another surface
10.3 Types of walls
Type of wall Description
Non load  Define as :
bearing wall  Concrete frames are typically rigid frames and qualify as
non combustible, fire-resistive construction.
 Non combustible steel frames may utilize moment
connections and require fireproofing to qualify as fire-
resistive construction.
 Timber frames require diagonal bracing or shear planes
for lateral stability and may qualify as heavy timber
construction if used with non-combustible, fire-resistive
exterior walls and if the members meet the minimum size
requirements specified in the building code.
 Steel and concrete frames are able to span greater distances
and carry heavier loads than timber structures. •
Load bearing  Define as :
wall  Use in construction of :
a. Masonry wall
b. Pre Panelised Load Bearing Metal Stud Walls
c.
11.0 WALL CLADDING
11.1 Introduction
 Wall Cladding can be defines as the visible external finish of a building.
 Wall cladding is a non structural external finish , as opposed to a load bearing
external construction.
 Cladding is often prefabricated into panels that arae attached to the structural
frame of building,
 Cladding can be purchased ‘off the shelf’ or on the market easily.
 Cladding must be designed to have adequate strength and stifness to resist load
since wind will effect positive & negative pressure n surface of building.

11.2 Function of wall cladding

 Create a controlled internal environment
 Provide privacy
 Provide thermal insulations
 Prevent the spread of fire
 Protect building from externa conditions : Example, weather outside building is
too hot for the wall. Hence, wall cladding will protect it.

11.3 Types of cladding

 There are many types of cladding that have been used in the construction of
building.
 Common cladding that usually been used are:
Cladding wall Description
a. Curtain  A non structural cladding system for the external walls of
wall building
 Only support their own weight and the loads are imposed on
them, which they transfer back to the primary structure of
building.
 Designed to resist air and water infiltration, sway indiced by
wind and seismic forces acting on the building and its own
dead load weight forces.
 There are two types of curtain wall , which are:
i. Stick system : Installed piece by piece on site
 ii. Unitised : Prefabricated modules offsite and deliverd in
panels.
b. Tensile  The membrane is formed by a structural fabric, consisting of
Fabric a woven base cloth, coated on both sides, and held in
Covering position by tension forcesimposed by a structural
framework.
 Can be relatively quick to construct and can be relocatable
making them suitable for temporary use.
 Fabric structure are tensile structure in which a membrane is
strestched to form a 3-D surface that can be use as shading,
roof or decorative component.
c. Metal  Commonly used for agricultural, industrial, retail and
Profile leisure buildings.
Cladding  Sheets are manufactured in a range of corrugated and other
profiles, such as trapezoidal, sinusoidal or half round.
 Types of metal that are commonly used are:
i. Steel
ii. Aluminium
iii. Zinc
iv. Copper
v. Composite Panel
12.0 STEEL IN BUILDING
12.1 Introduction
i. Steel
 Steel is an alloy of iron and other elements such as carbon.
 Carbon content is not more than 2% and the rest is iron.
 Steel widely used in construction due to its high tensile strength and low cost.
 Steels can be categories as mild, medium or high based on the percentage of
carbon.
 It is a major component in building, infrastructure, tools, ships, automobiles,
machines, appliances and weapons.
ii. Steel structure
 Steel structure is steel construction material which fabricated with a specific
and chemical composition to suit the specifications.
 It is made of structural steel components that connect with each other to carry
loads and provide full rigidity.
 Steel has high strength grade of steel and it makes the structure reliable and
require less raw materials compared to concrete structure and timber
structure.
 In modern construction, steel structure is used for almost every type of
structure including heavy industrial buildings, multi-storey buildings,
equipment support systems, infrastructure, bridges, towers, airport terminals,
etc.
12.2 Application of steel structure
 There are three basic types of steel in the construction. These may be
designated as :
i. Engineering construction
- Define as construction that involves in designing, planning,construction and
management of infrastructures such as roads, tunnels, bridges, airports,
railroads, facilities, buildings, dams, utilities and other projects.
ii. Skeleton construction
- A method of constructing high buildings in which the chief horizontal and
vertical members are of rolled steel and the walls are for the most part
supported at the floor levels by the steel frame itself.
iii. Long-span construction
- Long-span constructions create unobstructed, column free spaces greater
than 30 metres for variety of functions. These include activities where
visibility is important for large audiences, flexibility and where moveable
objects are housed. Example of long-span buildings such as auditorium,
covered stadium, exhibition halls and aircraft hangar

12.3 Properties of steel

Physical Mechanical Chemical
 Density of 7,850  Can easily be moulded  Oxidation
kg/m3 and it is 7.85 to form any desired
times as dense as shape
water.
 Melting point of 1,510  Can easily be moulded  Corosion
C which is higher than to form any desired
that of most metals shape
and boiling poimt
 Steel has lower  Ductility  Toxicity
thermal conductivity
than aluminum
12.4 Advantages & Disadvantages of steel
Advantages Disadvantages

▪ Flexible : Steel can be mold into any ▪ Heat conductivity : Heat is a good
shape, without changing its properties. absorber of heat. Hence, it will absorb
▪ Tensile : It has a high strength to heat from outside bulding and effect
weight ratio which means it has high environment inside. Plus, extreme heat
strength per unit mass. can warp or weaken steel to threaten the
▪ Can be easily fabricated and structural integrity of the residential
produced massively : Steel sections dwelling
can be produced off-site at shop floors ▪ Corrosion : Steel is an alloy of iron.
and then assembled onsite. This saves This makes it susceptible to corrosion.
time and increases the efficiency of ▪ Can bend in fires : While steel itself
the overall construction process. isn’t flammable, it is an excellent
▪ Cheap : Structural steel is relatively conductor of heat. This means that if fire
cheap compared to other building comes into contact with it, the fire can
materials spread to any material the steel touches.
▪ Recyclability : Steel undergo a
recycling process every year and being
reshaped into new forms that are just
as durable and tough as originally
sourced materials.
▪ Reduced construction costs :
Advances in steel fabrication
techniques mean that pieces can come
premade to a certain specification, so
that on-site rework will not be required
to make it the right size. Thus, it
reduces labour costs and the potential
for structural integrity weaknesses to
be introduced into the construction.
12.5 Structural steel shapes
Steel shape Description
i. S-shape ▪ Design provides less cross sectional area in flanges which make it
less strength compared to W-shape.
▪ Has slope approximately 17 degrees on the inner of flange sufaces.
▪ The flanges in addition to the vertical elements allow for perfect
bending capabilities when necessary.
ii. W-shape ▪ Most widely used structural member for beams, columns and other
load-bearing applications.
▪ It has parallel inner and outer flange surfaces that are of constant
thickness.
▪ Provides greater cross sectional are in the flanges, which results in
greater strength compared to S-shape.
iii. C-shape ▪ Also known as C-beams.
▪ Created with top and bottom flanges that create a C shape.
▪ It is similar to S-shape in that its inner flange surface is also
approximately 17 degrees,
▪ Useful in locatiions where a single flat surface on one side is
required. Usually when used alone, the C-shape is not very efficient
as a beam or column.
▪ Connected by rivets or wels.
iv. Steel plate ▪ A structural member that has a width greater than 200mm and a
thickness of 6mm or more
▪ Plates are generally used ad connections between other structural
members.
▪ They may also be used as component parts of built-up structural
members, such as built column.
v. Steel Angles ▪ Angles are used primarily to support, brace or connect other
structural members.
▪ They may be used as single members or in combinations of two or
four to form main members.
▪ Provides great stability for floor systems all while reducing
structural depth simultaneously.
12.6 Steel protection
Protection Methods

i. Agains fire  Steel frame needs to be protected from fire becasue steel
siftens when in high temperature and this can cause the
building partially collapse.
 Methods can be used to against fire are :
i. Encasing column in some form fire resistant structure such
as masonry, concrete or plasterboard.
ii. Beams may be cased in concrete, plasterboard or sprayed
with coating to insulate it from the heat of the fire or it can
protected by a fire resistant ceiling construction.
iii. Intumescent coating are also method of attaining this
additional fire protection.
ii. Against corrosion  Corrosion of steel is an electrochemical reaction that
requires the presence of water, oxygen and ion such as
chloride ion.
 Methods can be used :
i. Coating
- Most common metallic coating used to protect steel
construction products is hot dip galvanising.
- The process involves are, coating the surface of steel with a
very thin coating anti corrosion or resistant metal.

12.7 Steel Jointing ( Connctors)

Type of steel Description
jointing
Bolts Most common, easy to use and reqire litte special treatment.
The development of higher steels and improved manufacturing
processh have resulted in the production of bolts that produce
strong structural steel connections.
There are two type of bolts being installed which are typical
 bolted joint and proposed bolted joint.
Welds Highly speacialized skill
Welding of load bearing parts of a structure should be
performed only by properly qualified personnel.
Rivets Used for a very long time, which is tradisional method.
Made up of :
- Round Ductile steel bar called shank
- A head at one end
The length of rivet should sufficient to form the second head
Design very similar to bearing type of bolted connection.
13.0 PORTAL FRAME
13.1 Introduction
Portal frames are made in a variety of shapes and sizes. They are usually made from
steel, but can also be made from concrete or timber.
Designed in such a way that it has no intermediate columns, as a result large open
areas can easily be created within the structure.
Generally used for single storey construction which require a large unobstructed floor
space such as : Factories, Shopping Complex & Warehouse

13.2 Type of portal frame

Portal frame Description
ii. Pitched roof  25 to 35 m are the most efficient spans
symmetric
iii. Portal frame with  Floor Office accommodation is often provided
internal within a portal frame structure using a partial width
mezzanine mezzanine floor
iv. Crane portal  Brackets can be fixed to the columns to support the
frame with crane rails
column brackets
v. Tied portal frame  The horizontal movement of the eaves and the
bending moments in the columns and rafters are
reduced.
vi. Mono-pitch  Simple variation of the pitched roof portal frame, and
portal frame tends to be used for smaller buildings (up to 15 m
span).
vii. Propped portal  The span of a portal frame is large and there is no
frame requirement to provide a clear span, a propped portal
frame can be used to reduce the rafter size and also
the horizontal shear at the foundations
viii. Mansard portal  Use where a large clear height at mid-span is
frame required but the eaves height of the building has to
be minimised.
ix. Curved rafter  Portal frames may be constructed using curved
portal frame rafters, mainly for architectural reasons.
x. Cellular beam  Rafters may be fabricated from cellular beams for
portal frame aesthetic reasons or when providing long spans.
13.3 Advantages and Disadvantages of Steel Portal Frames
Advantages Disadvantages
 Speed and ease of erection  Easily corrode
 Framework prefabricated in a  Steel is incombustible it has a poor
workshop and not affected by resistance to fire as it bends easily
weather when hot.
 Site works such as drainage,  Expensive to bend
roads etc can be carried out until  Need maintenance such as re-
framework is ready for erection. painting
 Connected together in factories
by welding and site connections
should be bolted.

13.4 Joint for Portal Frame

i. Base Joint for Portal Frame
 The legs or stanchions of the portal frame need connecting at the bottom to a
foundation.
ii. Ridge Joint for Portal Frame
 The joint must be strong, hence the use of wedge shaped pieces called gusset
pieces to strengthen and increase the bolt area
iii. Knee Joint for Portal
 Knee joint must be strong to support the roof loads and prevent bending.
 Gusset pieces will be used to increase strength, give greater bolt area and
prevent deflection under load
iv. Diagonal Bracing for Portal Frame
 Used to help strengthen the framework and prevent movemen
v. Cladding Rails for Portal Frame
 Cladding ails can be fixed horizontal or vertical depending on the way the
cladding panels are fixed.
vi. Tie Cables for Portal Frame
 Wire and tubular ties are used to prevent sagging of the cladding rails which
can add considerable force unto the joints of the external cladding.
14.0 SPACE FRAME
14.1 Introduction
 Space frame is a long-spanning three dimensional plate structure based on the
rigidity of the triangle and composed of linear elements subject only to axial
tension or compression.
 Simplest spatial unit of a space frame is a tetrahedron having four joints and six
structural members.
 Usually utilize a multidirectional span, and are often used to accomplish long
spans with few supports.

14.2 Advantages and Disadvantages of Space Frame

Advantages Disadvantages

 Controlled load distribution  High cost compared to portal frame

 Versatility design freedom  The lifespan depend on the system
 Lightweight  used during construction.
 Supports all types of roofing  Can be hard to extend and build on
 Random column placement   Need space for crane
column-free spaces

14.3 Type of Space Frame

 Commonly type of space frame can be classified according based on few
elements, such as :
Elements Description
a. According to 1. Flats covers
Curvature  Composed of planar substructures. The plane are
channeled through the horizontal bars and the
shear forces are supported by the diagonals
2. Has a cross section of a simple arch
 Usually this type of space frame does not need to
use tetrahedral modules or pyramids as a part of
its backing.
3. Spherical domes
  Usually require the use of tetrahedral modules or
pyramids and additional support from a skin.
 A spherical/ geodesic dome is a spherelike (parts
of spheres, like half a ball) structure composed of
a complex network of triangles.
d. According to the 1. Two and three-way grids
number of grid  Characterized as two way or three way
layers
2. Single, Double and Triple Layered
 Single layer frame has to be singly or doubly
curved. Commonly used space frames are double
layered and flat.
 Triple layered is practically used for a large span
building
15.0 SHORING
15.1 Introduction
 Shoring can be define as temporary structure used to support vertical loads during
the process of construction.
 The loads supported can be from freshly placed concrete, existing structures, or
from construction equipment
 All shoring must be designed by a qualified person. Additionally, the services of
a qualified engineer will most likely be required, particularly if columns and
footings are removed.

15.2 Function of Shoring

 Supporting work for excavation
 To support building structure/element during construction
 Formwork for concreting
 Allow alteration or modification be made safely to the building

15.3 The use of shoring

 To give support to walls which are dangerous or are likely to become unstable
due to subsistence, bulging or leaning.
 To avoid failure of sound walls caused by the removal of adjacent support e.g.
where a basement is being constructed near to sound wall.
 During demolition works to give support to an adjacent building or structure.
 To support the upper section of a wall during the formation of a large opening
below such supporting section.

15.4 The type of shoring

Type of shoring Description
Raking shores  Raking shores consists of inclined boritis called
rakers. One end of the raker is placed against the wall
whilst the other sits on the ground. 
 Used to support walls that have begun to lean or
bulge.
 The most effective support is given if the raker meets
the wall at an angle of 60 to 70 degrees.
  Suitables material are timber structural steel and
framed tabular scaffolding
 Necessary to use both raking and dead shores together
Flying Shores  Flying shores are simply flat boritis struts used to
provide temporary support to two parallel walls where
one or both show signs of failure.
 The most common use for this kind of support is
where one building in a terrace has collapsed and
some support has been lost to the building on either
side.
 Two type of flying shoring which are :
- Single flying shore : For distances between walls of up to
9m or less.
- Compound flying shore : . For distances up to 15m
Dead shores  Consists of an arrangement of beams and posts which
(Also known as are required to support the weight of the structure
Vertical shores) above and transfer same to the ground on firm
foundation below.
16.0 UNDERPINNING
16.1 Introduction
 Underpinning can be defined as the process of strengthening and stabilizing the
foundation of an existing building or other structure.
 The main objective of most underpinning work is to transfer the load carried by a
foundation from its existing bearing level to a new level at a lower depth.
 Underpinning techniques can also be used to replace an existing weak foundation.

16.2 Reasons for underpinning

 Underpinning operation may be necessary for one or more of the reasons, such
as :
Reason Description
a. Uneven  Caused by uneven loading of the building, unequal
Settlement resistance of the soil action of tree roots or
cohesive soil settlement.
b. Increase in  Due to the addition of an extra story or an increase
Loading in imposed loadings such as that which may occur
with a change of use.
c. Lowering of  Usually required when constructing a basement
Adjacent Ground adjacent to existing foundations.
d. Original  Example,because of decays of timber piles under
foundation is not the foundation
strong or stable
e. Existing  caused by poor soil or changes to the soil
foundations of the conditions
building have
moved
16.3 Precautions of underpinning
 General Precautions before any form of underpinning work is commenced the
following precautions should be taken:
i. Notify adjoining owners of proposed works giving full details and temporary
shoring or tying.
ii. Carry out a detailed survey of the site, the building to be underpinned and of any
other adjoining or adjacent building or structures. A careful record of any defects
found should be made and where possible agreed with the adjoining owner(s)
before being lodged in a safe place
iii. Indicators or `tell tales' should be fixed over existing cracks so that any
subsequent movements can be noted and monitored
iv. If settlement is the reason - investigation should be carried out to establish the
cause and any necessary remedial work put in hand before any underpinning
works are started
v. Before any underpinning work is started the loads on the building to be
underpinned should be reduced as much as possible by removing the imposed
loads from the floors and installing any props.
vi. Any services which are in the vicinity of the proposed underpinning works should
be identified, traced, carefully exposed, supported and protected as necessary.

16.4 Methods of underpinning

Standard methods of underpinning are :
Method Description
Traditional  Traditional underpinning is the process of constructing a
underpining new foundation beneath an existing one to a deeper level
where the soil has a greater load bearing capacity.
 It is to prevent fracture, damage or settlement of the
wall(s) being underpinned the work should always be
carried out in short lengths called legs or bays.
 Advantages of traditional underpinning :
1. Occupants can remain in the property as work can be
completed from outside.
2. Method can be used in restricted access areas.
3. Low cost solution at shallow depths.
4. Minimal disruption and noise generated
Needle Beams  This method of underpinning can be used where the
Underpinning condition of the existing foundation is unsuitable for
traditional or jack pile underpinning techniques.
 The brickwork above the existing foundation must be in
a sound condition since this method relies on the
`arching effect' of the brick bonding to transmit the wall
loads onto the needles and ultimately to the piles. 
 The piles used in this method are usually small diameter
bored piles.
Cantilever Beams  This method stabilises existing wall foundations either
internally or externally whichever the most appropriate.
 This system is used where traditional underpinning is
not appropriate due to the existing foundations being
deep that it is uneconomical to dig. (depths greater than
1.5m).
 Advantages :
1. Faster than traditional underpinning 
2. Access from one side only 
3. Occupants can stay in the property during construction
 Suitable for restricted access 
4. Cantilever beam constructed at a higher level if existing
foundation too deep
Raft Underpinning:  Stabilises existing wall foundations to whole rooms or
buildings.
 Mini piles are installed within the property and capped
with an integral reinforced concrete raft.
 Needle beams project from the slab into walls below
ground level.
 Use where whole rooms or whole structures are to be
underpinned and includes the provision of a new integral
floor slab.
 Advantages:
1. Provides lateral traverse ties throughout the structure
2. Provides new floor slab upon completion
3. Economical at depths greater than 1.5m
 4. No need for external access
5. Minimise disruption to drainage and services
Jack Pile  Use when the depth of a suitable bearing capacity
Underpinning subsoil is too deep to make traditional underpinning
uneconomic
 Quiet, vibration free and flexible since the pile depth can
be adjusted to suit subsoil conditions encountered.
 Existing foundations must be in a good condition since
they will have to span over the heads of the pile caps
which are cast onto the jack pile heads after the
hydraulic jacks have been removed.
Pynford' Stool  Use where the existing foundations are in a poor
Method of condition and it enables the wall to be underpinned in a
Underpinning continuous run without the need for needles or shoring.
 The reinforced concrete beam formed by this method
may well be adequate to spread the load of the existing
wall.