ADDIS ABABA UNIVERSITY

ADDIS ABABA INSTITUTE OF TECHNOLOGY

DEPARTEMENT OF CIVIL ENGINEERING

BUILDING CONSTRUCTION (CENG 3103)

CHAPTER-6
WALL SUSTEMS
CONTENTS
 Introduction
 Types of walls
 External walls
 Materials for external walls
 Types of external walls
 Walls of block construction
 Internal walls
 Cavity walls
 Opening in walls
WALL SYSTEMS
1. INTRODUCTION
 The primary function of wall is:
 To enclose or divide space of a building to make it more
functional and useful.
 To provide privacy and afford security
 Give protection against heat, cold, sun and rain
 Also to provide support to floors and roofs.

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WALL SYSTEMS
1. INTRODUCTION (cont...)
 The functional requirements of a wall are:

Strength and stability

Resistance to weather
Durability and freedom from maintenance
Fire resistance
Resistance to passage of heat
Resistance to passage of sound

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WALL SYSTEMS
2. TYPES OF WALLS
 A distinction between various types of wall can be made in two

different ways:
Foundation
walls
Walls in sub
structure
Basement
Based on walls
their position
in the
building External walls
Walls in super
Types of structure
walls Internal walls
Load bearing
walls
Based on
their function
Partition
walls
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WALL SYSTEMS
2. TYPES OF WALLS (CONT...)
 Foundation walls

 The function of foundation wall is to transmit loads coming

from the super structure.
 Confine the soil and hardcore in the substructure
 Load bearing capacity and resistance against effect of the
underground, such as swelling pressure, uplift pressure and
chemical attack should be taken into consideration.
 Basement walls
 The function of basement wall is to:
• Support vertical loads (if load bearing)
• Resist lateral loads, and
• Protect the building from dampness.
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WALL SYSTEMS
2. TYPES OF WALLS (CONT...)
 External walls:

 Must provide protection against wind and rain, should insulate heat
 Be water repellent, fire resisting and capable of sound insulation.
 Internal walls:
 Internal walls are basically required to separate rooms.
 They should have sufficient sound and heat insulating capacity and
should be water repellent.
 Load bearing walls:
 The strength must be sufficient to carry the loads placed on it.

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WALL SYSTEMS
3. EXTERNAL WALLS
3.1 MATERIALS FOR EXTERNAL WALLS
 Different materials are employed for the construction of external

walls such as: brick, stone, HCB, RCC, glass, metals and plastics,
chika, etc.
 The materials employed depend on several factors such as:

 Local availability of the material

 The standard of the house planned
 Climatic conditions
 Cost of the material
 Aesthetic requirements
 Skilled labour availability
 Function of the wall to be constructed
 Fire resistance requirement

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WALL SYSTEMS
3.2 TYPES OF EXTERNAL WALLS
 External walls can be classified in different groups according to

their structural functions and physical nature.

Load bearing
Based on
structural
function Non-load
bearing
Types of
external walls Block
construction

Based on their Monolithic

physical nature construction
Composite or
panels
construction
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WALL SYSTEMS
3.2.1 WALLS OF BLOCK CONSTRUCTION
 Walls composed of stones, bricks or HCB are of block construction.

 They are formed from fairly small units set in matrix of cement
mortar.
 The properties and strength of such wall depend on:
 Quality of masonry material
 Quality of mortar
 Method of bonding used

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 WALL SYSTEMS
A. BRICK WALLS
Manufacturing of clay bricks
 There are generally four basic stages in brick manufacturing:

MOULDIN
FIRING
• Excavation, G • Dryer chamber
storage • Tempering • Sun dry • Firing in kiln
• Grinding, • Mixing • Crack control • Vertification
blending • Moulding • Sintering
CLAY
DRYING
PREPARATIO
N

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WALL SYSTEMS
Types of clay bricks
 Different types of bricks can be produced depending on the types of

clay, the moulding and firing process:

i. Common bricks ii. Facing bricks

• Ordinary bricks • Designed to give attractive
• Not designed to provide appearance
good finished appearance • Free from imperfections
& highest strength such as cracks & size
• The cheapest brick variations

iii. Engineering bricks iv. Fire bricks

• Designed for strength & • Made of special fire clay
durability • Used for lining in fire
• High density & well fired places, furnaces, etc.
where high temperatures
are prevalent. 12
 WALL SYSTEMS
Tests for bricks

Field test for burnt

Field test for soils Laboratory tests
clay bricks

• Balls of about 8cm are • Appearance: shape, • Compressive strength:

moulded with hands & plainness, color checks direction of loading
allowed to dry. • Hammer test: properly same as that to be
• If it is clay when it burnt & free from applied in practice.
dries it becomes as hard cracks brick emits a • Water absorption: 24 hrs
as stone if not it easily metallic ring. cold water or 5 hrs
falls apart • Hardness test: boiling water test.
scratching surface with • Efflorescence: results
a knife. from dissolved salts &
spoils the appearance .

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WALL SYSTEMS
Tests for bricks

MINIMUM COMPRESSIVE STRENGTH OF BRICK (ES C.D4.001)

Class Average of 5 brick [MPa] Individual brick [MPa]

A 20 17.5
B 15 12.5
C 10 7.5
D 7.5 5.5

MAXIMUM WATER ABSORPTION (ES C.D4.001)

class 24-hrs immersion (%) 5-hrs immersion (%)
Avg. of 5 bricks Individual brick Avg. of 5 bricks Individual brick
A 21 23 22 24
B 22 24 23 24
C,D No limit No limit No limit No limit

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WALL SYSTEMS
Brick masonry
 Brick masonry is sometimes preferred over other types of masonry

for the following reasons:

 Bricks are of uniform size and shape, and hence they can be
laid in any definite pattern.
 Bricks are light in weight and small in size. Hence they can
be easily handled.
 Brick do not need any dressing.
 Ornamental works can be easily done with bricks.

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WALL SYSTEMS
A) BRICK WALLS (CONT...)
Terminologies
 Course: A course is a horizontal layer of masonry units.

 Stretcher: A stretcher is the longer face of a brick as seen in the

elevation of the wall.

 Header: A header is the shorter face of a brick as seen in the elevation

of the wall.
 Lap: Lap is the horizontal distance between the vertical joints of

successive brick courses.

 Bed: Bed is the lower surface of the brick when laid flat.

 Closer: It is a portion of the brick with the cut made longitudinally and

is used to close up bond at the end of the course.

 Queen closer: It is a portion of a brick obtained by cutting a brick
length wise into two portions.
 King closer: It is obtained by cutting the triangular piece between
the center of one end and the center of the other side.
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WALL SYSTEMS
Terminologies (cont...)
 Bevelled closer: A special form of king closer in which half width
is maintained at one end and full width is maintained at the other
end.
 Mitred closer: It is a portion of a brick whose one end is cut
splayed or mitred for full width.
 Bat: It is the portion of the brick cut across the width. Thus, a bat is

smaller in length than the full brick.

 Half bat: equal to half the length of the original brick
 A three-quarter-bat: its length equal to three-quarters
 Bevelled bat: A bat with its width bevelled
 Racking back: It is the termination of a wall in a stepped fashion.

 Toothing: It is the termination of the wall in such a fashion that

each alternate course at the end projects.

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WALL SYSTEMS
Terminologies (cont...)

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WALL SYSTEMS
Rules for bonding
 For getting good bond, the following rules should be observed:

i. The brick should be of uniform size. The length of the brick

should be twice its width plus one joint.
ii. The amount of lap should be minimum ¼ brick along the
length of the wall and ½ brick across the thickness of the wall.
iii. Use of brick bats should be discouraged, except in special
locations.
iv. In alternate courses, the center line of header should coincide
with the center line of the stretcher, in the course below or
above it.
v. The vertical joints in the alternate courses should be along the
same perpend.
vi. It is preferable to provide every sixth course as header course
on both sides of the wall.

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WALL SYSTEMS
Types of brick bonds
 Bond is the system of laying bricks in such a manner that there is no

vertical joint in any row or course immediately above or below the one
considered.
i. Stretcher bond
 Is the one in which all the bricks are laid as stretchers on the faces of the

wall.
 This pattern is used only for those walls which have thickness of half

brick. Used as partition walls, sleeper walls, chimney stacks, etc

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WALL SYSTEMS
Types of brick bonds
i. Stretcher bond

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WALL SYSTEMS
ii. Header bond
 Is the one in which all the bricks are laid as headers on the faces of walls.

The width of the brick is along the direction of the wall.

 The pattern is used only when the thickness of the wall is equal to one

brick.
 This bond does not transmit pressure in the direction of the length of the

wall. Thus it is unsuitable for load bearing walls.

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WALL SYSTEMS
iii. English bond
 This is the most commonly used bond, for all wall thickness. And it is

considered to be the strongest.

 The bond consists of alternate courses of headers and stretchers.

 The vertical joints of the header courses come over each other, the same

goes for stretcher courses.

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WALL SYSTEMS
iii. English bond

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WALL SYSTEMS
iii. English bond

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WALL SYSTEMS
iv. Flemish bond
 Each course is comprised of alternate headers and stretchers

 Every alternate course starts with a header at the corner (i.e. Quoin

header). Quoin closers are placed next to the quoin header in alternate
courses to develop the face lap.
 Every header is centrally supported over the stretcher below it.

Double Flemish bond: each course presents the same appearance both in
the front face as well as in the back face.
• Alternate headers and stretchers are laid in each course.
• It presents better appearance than English bond.
Single Flemish bond: Comprised of double Flemish bond facing and
English bond backing and hearting in each course.
• It combines the strength of English bond and appearance of
Flemish bond.

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WALL SYSTEMS
iv. Flemish bond

Double Flemish

Elevation
Single Flemish
Double Flemish

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WALL SYSTEMS
iv. Flemish bond

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WALL SYSTEMS
Joints in brickwork
 Joints are the weakest part of a masonry structure and they require

special care in laying and finishing.

 The purpose of finishing joints is to improve the appearance of

brickwork and to make it more water proof.

 The finishing of joints as the brickwork proceeds is termed as jointing

whereas finishing of joints after the brickwork has been completed is

called pointing.

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WALL SYSTEMS
Types of pointing finishes
 Generally, brickwork is jointed by striking, raking or rubbing the mortar

while it is green.
 Pointing consists of raking out the green mortar in the joint to a depth of

about 20mm and then refilling the joint with fresh mortar.
 Flush or flat pointing: are formed by pressing mortar in the raked
joint and by finishing off flush with the edges of masonry unit.
• This type of pointing does not give good appearance, however,
it is more durable since it does not provide any space for the
accumulation of dust, water, etc.
 Struck pointing: this is a modification of flush pointing in which
the face of pointing is kept inclined, with its upper edge pressed
inside.
• The point permits water to drop off from the face off the
brickwork. The appearance is not satisfactory.

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WALL SYSTEMS
Types of pointing finishes
 Recessed pointing: is done by pressing the mortar back from the
edges by 5mm or more. The face of pointing is kept vertical by a
suitable tool.
• The pointing gives very good appearance in face-work for good
Recessed
textured bricks and good quality of mortar.
 Concave pointing (keyed): It is formed by a round jointer and it
gives a very attractive appearance to the brickwork.
 V-pointing: It is made in a manner similar to concave pointing by
forming V-groove in the flush-finishing face.
 Projecting pointing: a special type of pointing formed by a suitable
slighted steel rod.
• Such type of pointing gives good appearance but is liable to
damage easily.

Projecting

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WALL SYSTEMS
Reinforced brickwork
 Reinforced brick work is the one in which the brick masonry is

strengthened by the provision of mild steel flats, hoop iron, expanded

mesh or bars. It is adopted or used for the following circumstances:
i. When the brick work has to bear tensile and shear stresses.
ii. When it is required to increase the longitudinal bond.
iii. When the brick work is supported on soil which is susceptible to large
settlement
iv. When the brick work is supposed to act as a beam or lintel over
openings
v. When the brick work is to resist lateral loads, such as retaining walls
etc.
vi. When the brick wall is to carry heavy compressive loads.
vii. When the brick work is to be used in seismic areas.

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WALL SYSTEMS
Reinforced brickwork
 Brickwork can be reinforced in one of the following way:

i. Reinforcement may consist of iron bars of expanded metal mesh.

Usually the metal mesh is provided at every third course.

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WALL SYSTEMS
Reinforced brickwork
ii. Another type of reinforcement is hoop iron. Theses are steel flats
about 2.5-3 cm in width and are from 1.5-2.5 mm in length.
• Two strips of hoop iron are used for header bricks and one hoop
iron for stretcher bricks, and every sixth coarse is reinforced
iii. For walls that have to withstand pressure vertical reinforcement
passing through openings made in special types of brick is
employed.

Hoop iron reinforcement

Reinforced brick work

retaining wall 34
WALL SYSTEMS
Causes of failure of brick masonry
 Brick masonry may fail due to the following three major causes:

i. By crushing if it is overloaded
 Can be prevented by providing adequate dimensions
ii. By shearing along any horizontal plane
 Can be prevented by providing a strong mortar
iii. By rupture along a vertical joint under vertical loads.
 Can be prevented by breaking vertical joints in brickwork
Defects in brick masonry
 Brick masonry may develop the defects due to the following reasons:

 Sulphate attack
 Crystallization of salts from bricks
 Corrosion of embedded fixtures
 Drying shrinkage

35
WALL SYSTEMS
Maintenance of brickwork
 Brick walls can be maintained using alternative methods among

which the following are widely used in practice:

i. Re-pointing old brickwork
ii. Repainting brickwork
iii. Cleaning brickwork
iv. Removal of efflorescence

Mechanism of efflorescence in brickwork

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WALL SYSTEMS
B) STONE WALLS
 The stones used for masonry should be hard, durable, tough and

sound and free from weathering, decay or defects like cavities,

cracks, sand holes, injurious veins, patches of loose or soft materials
etc.
 Rocks from which building stones are obtained, are divided into

three groups:
i. Igneous rock: the chief building stones in this class are
trachyte, basalt, granite, etc.
ii. Sedimentary rocks: The principal building stones in this
group are lime stones and sand stones. These are used in
floors, steps, facing works, columns, walls etc.
iii. Metamorphic rocks: the common building stones are slate
and marble. Since marble is costly it is not used for masonry
but used for flooring, facing work, steps, ornamental works
etc.
37
WALL SYSTEMS
B) STONE WALLS
CLASSIFICATION OF ROCKS

ROCK

GEOLOGICAL PHYSICAL CHEMICAL HARDNESS

SILICONS SOFT ROCKS

STRATIFIED
IGNEOUS

MEDIUM
ARGILLACEOUS
SEDIMENTARY UNSTRATIFIED ROCKS

HARD
METAMORPHIC FOLIATED CALCAREOUS
ROCKS

VERY HARD
ROCKS
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WALL SYSTEMS
B) STONE WALLS
TESTS FOR STONES
 Building stones are tested for their different properties:

i. Attrition test: This test is carried out to find out the rate of
wear of stones (Daval’s attrition test machine).
ii. Crushing test: The compressive strength of stone can be
found out with the help of this test.
iii. Hardness test: To determine the hardness of a stone
(Dorry’s testing machine). Coefficient of hardness is
determined.
iv. Impact test: to determine the toughness of a stone.
Toughness index is determined.
v. Water absorption test: to determine the water absorption
capacity of a stone.

39
WALL SYSTEMS
B) STONE WALLS
QUALITIES OF GOOD BUILDING STONE
 A good building stone should posses the following qualities.

i. Crushing strength: The crushing strength of stone should

be greater than 100 N/mm2.
ii. Appearance: stones for face work should be decent in
appearance, capable of preserving their color uniformly
and free from clay holes, spots of other colors etc.
iii. Durability: A good building stone should be durable which
depends up on its chemical composition, texture,
resistance to environment and positioning.
iv. Facility of dressing: It should be such that they are easily
carved, moulded, cut and dressed.
v. Hardness: The coefficient of hardness should be more
than 17.
40
WALL SYSTEMS
B) STONE WALLS
QUALITIES OF GOOD BUILDING STONE (CONT...)
vi. Percentage wear: The wear of stone should be maximum
3%.
vii. Specific gravity: specific gravity of good stone should be
minimum 2.7.
viii. Texture: It should have compact fine texture free from
cavities, cracks and soft fragments.
ix. Toughness index: T.I. > 19 good stones, T.I < 13 poor stones.
x. Water absorption: Different stones have different water
absorption depending upon the porosity.
xi. Weathering: A good stone should be able to resist the
environment attack.
xii. Fire resistance: A good stone must preserve its shape in case
of fire.

41
WALL SYSTEMS
B) STONE WALLS
CLASSIFICATION OF STONE MASONRY (CONT...)
 Depending upon the arrangement of stones in the construction,

degree of refinement used in shaping the stone and finishing

adopted stone masonry can be classified as:
i. Rubble masonry:
 The block of stones used are either undressed or
comparatively rough dressed.
 The masonry has wide joints, since stones of irregular sizes
are used.
ii. Ashlar masonry:
 Consists of blocks of accurately dressed stone with
extremely fine bed and end joints.
 The blocks may be either square and rectangular shape. The
height of stone varies from 25-30 cm
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 WALL SYSTEMS
B) STONE WALLS
CLASSIFICATION OF STONE MASONRY (CONT...)
Stone
Masonry

Rubble Masonry Ashlar Masonry

Fine tooled
Random Rubble Square Rubble Miscellaneous Types Dry Rubble
Rough tooled

Polygonal
Un-coursed Un-coursed Rock faced
walling

Built to Built to courses Flint Chamfered

courses walling

Regular Block in course

coursed

Facing
43
WALL SYSTEMS
RUBBLE MASONRY

44
WALL SYSTEMS
II. ASHLAR MASONRY

45
WALL SYSTEMS
DRESSING OF STONES
 The surface of stones obtained from quarry are rough. The blocks

are irregular in shape and non uniform in size. Hence their dressing
is essential.
 It serves the following purposes:

i. It gives desired aesthetic appearance.

ii. It makes transport easy and economical.
iii. It suits the desired requirements.
iv. It helps taking advantage of locally available skilled labour

46
WALL SYSTEMS
B) STONE WALLS
DETERIORATION OF STONES
 Various environmental and external agencies play an important role

to deteriorate stones:
i. Alternate heating and cooling: Repeated contraction and
expansion cause cracking of stones due to internal stresses.
ii. Alternate wetting and drying: repeated wetting and drying
result in wearing it out quickly.
iii. Thawing and freezing: it results in entrapping of moisture
which expand on freezing resulting in splitting of stones.
iv. Nature of mortar: The mortar may react chemically with
constituents of stone and leads to the disintegration of stones
v. Rain water:
vi. Vegetable growth:

47
WALL SYSTEMS
B) CONCRETE BLOCK WALLS
 One of the most common masonry units.

 It consists of hardened cement and may be completely solid or

contain single or multiple hollows.

 It is made from conventional cement mixes and various types of

aggregates. These include: sand, gravel, crushed stone, expanded

shale or clay, volcanic ciders (Pozzolana), scoria, pumice, etc.
 Various types of blocks are manufactured to be used for wall

construction.

48
WALL SYSTEMS
B) CONCRETE BLOCK WALLS
ADVANTAGES OF HOLLOW CONCRETE BLOCK MASONRY
A. Concrete blocks are regular in size, requiring no dressing work.
Hence construction is very rapid.
B. Blocks are light and therefore easy to handle.
C. Because of their lightness, the loads transferred to foundations is
much less than the stone masonry.
D. There is a great saving in the material.
E. Because of larger size of the blocks, the number of joints in the
masonry is less. This results in saving in mortar.
F. Because of hollow space, the resulting wall has better insulating
properties against sound, heat and dampness.
G. Blocks can withstand the atmospheric actions, and do not require
plaster or any other covering.

49
WALL SYSTEMS
MANUFACTURING OF CONCRETE MASONRY BLOCKS
 The following points should be kept in mind while manufacturing

the concrete masonry blocks:

i. The cement-aggregate ratio should not be leaner than 1:6.
ii. Blocks should be taken out from the moulds only when concrete
has sufficiently set.
iii. Machine casting is preferable to hand casting, to obtain better
finish.
iv. After taking the blocks out of mould they should be kept under
shade for a week and should be properly cured 3 to 4 weeks.
v. Bocks should be used only after about 3-4 weeks of curing.

50
WALL SYSTEMS
B) CONCRETE BLOCK WALLS
CONSTRUCTION OF CONCRETE BLOCK WALLS

51
WALL SYSTEMS
B) CONCRETE BLOCK WALLS
CONSTRUCTION OF CONCRETE BLOCK WALLS (CONT...)

52
WALL SYSTEMS
B) CONCRETE BLOCK WALLS
CONSTRUCTION OF CONCRETE BLOCK WALLS (CONT...)

Checking horizontal block spacing Filling in the walls b/n corners

Story or course pole

Cutting off excessive

mortar 53
WALL SYSTEMS
B) CONCRETE BLOCK WALLS
CONSTRUCTION OF CONCRETE BLOCK WALLS (CONT...)

Tooled mortar joints

54
WALL SYSTEMS
3.2.2 WALLS OF MONOLITHIC CONSTRUCTION
 Walls of monolithic construction could either be load bearing or not.

 The modern concrete wall and the primitive mud wall are composed
of materials, which are placed in a plastic state into a mould.
 Concrete walls can be plain or reinforced. The two greatest
advantages of concrete wall are:
 Strength, and
 Freedom it gives in design.
 Freedom of design is expressed by the ease with which it can be
made to take up curved or other complex shapes.
 Reinforced concrete wall thickness may be from 8cm up, and the
cost is generally higher but the strength of the structure is
considerably higher.

55
WALL SYSTEMS
3.2.2 PANELS OR COMPOSITE WALLS
 Panel walls are used whenever the load bearing functions of the wall

are taken over by a framework, which leaves the spaces in the

uprights to be filled.
 Generally they consist of two or more layers or sections each of

which fulfils a specific purpose

 They are principally used with the object of reducing weight.
 Requirements to be fulfilled are:
 Resistance to wind pressure,
 Protection against wind and rain, and
 Providing satisfactory appearance.
 Aluminum panels, Gypsum panels, etc.

56
WALL SYSTEMS
3.3 INTERNAL WALLS
PARTITION WALL
 A partition wall is a thin internal wall which is constructed to divide

the space with in the building into rooms or areas.

 A partition wall may be either non load bearing or load bearing.

Generally partition walls are non load bearing.

REQUIREMENTS TO BE FULFILLED
i. Should be strong enough to carry its own load
ii. Should be strong enough to resist impact to which the occupation
of the building is likely to subject them.
iii. Should have the capacity to support suitable decorative surface.
iv. Should be stable and strong enough to support suitable decorative
surface.

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WALL SYSTEMS
3.3 INTERNAL WALLS
v. Should be as light as possible.
vi. Should be as thin as possible
vii. Should act as sound barrier, specially when it divides two rooms.

viii. Should be fire resistance.

TYPES OF PARTITION WALLS
 Partition walls are of the following types:

♠ Brick partitions ♠ Clay block partitions ♠Concrete partitions

♠ Glass partitions ♠ Metal lath partitions ♠ Solid plaster
partitions
♠ Timber partitions ♠ Corrugated sheet partitions

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WALL SYSTEMS
4. CAVITY WALLS
 Cavity wall or hollow wall is the one which consists of two separate

walls, called leaves or skins, with a cavity or gap in-between.

 The thickness of the two leaves may be equal if it is non-load

bearing wall or the thickness of the inner may be increased to meet

the required structural strength.
 The inner and the outer leaves of the wall should not be less than

10cm in thickness through out the height of the wall.

 For a cavity wall to be effective, it is essential that the leaf is

entirely disconnected from the outer leaf, except for ties.

 The cavity varies from 4-10cm.

 The two leaves are securely tied together with suitable bonding steel

ties or sometimes with special bonding bricks.

 The ties should be placed at intervals not exceeding 1m horizontally

and 40 cm vertically.
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WALL SYSTEMS
4. CAVITY WALLS
ADVANTAGES OF CAVITY WALLS.
i. Damp prevention: cavity walls are able to prevent dampness
effectively.
ii. Insulation: cavity walls have about 25% greater insulating value
than the solid walls.
iii. Acoustic: cavity walls reduce sound and noise pollution.
iv. Economy: they are cheaper and economical.
v. Load reduction: loads on foundations are reduced because of
lesser solid thickness.

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WALL SYSTEMS
4. CAVITY WALLS (CONT...)

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WALL SYSTEMS
5. OPENINGS IN WALLS
 Openings are invariably left in the walls for the provision of doors,

windows cupboards, etc.

 These openings are bridged by the provisions of either a lintel or an

arch.
 Both lintels and arches are structural members designed to support

the loads of the portion of the wall situated above the openings.
5.1 Arches
 An arch is normally a curved member of either stone. Concrete,

steel, etc.
 Arches are constructed where:

 Loads are heavy,

 Span is large,
 Strong abutments are available, and
 Architectural appearance is required.
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 WALL SYSTEMS
5 OPENINGS IN WALLS
5.1 Arches (cont...)

Precast concrete arch lintel

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WALL SYSTEMS
5 OPENINGS IN WALLS
5.2 Lintels
 A lintel is a horizontal member, which is placed across the opening.

 Lintels are easy to build and the supporting walls need not be very

strong.
 At least 10cm length of bearing is a minimum requirement.

 For very long spans, the bearing for the lintel end should be equal at

least to its depth.

Types of lintels
 Lintels are classified according to the material of their construction.

a) Timber lintels: are the oldest type of lintels and are not
commonly used nowadays. They can not take greater load and
are vulnerable to fire and decay.

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WALL SYSTEMS
5. OPENINGS IN WALLS
5.2 Lintels (cont...)
Types of lintels
 Lintels are classified according to the material of their construction.

b) stone lintels: not widely used as the stone used for this work
is not available at all places.
c) Brick lintels: Plain brick lintels are not structurally strong
and they are not used in large openings and where loads are
heavy. Instead reinforced bricks are used.
d) Steel lintels: Are provided where the opening is large and
where the superimposed loads are heavy.
e) Reinforced concrete lintels: have replaced practically all
other types of lintels because of their strength, rigidity, fire
resistance, economy and ease in construction. Can be used on
any span and they may be cast in place or available as precast.
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