Ebook Interior design principles and practice - M. Pratap Rao: Phần 1

PREFACE
Interior design is a fast developing discipline. Its importance lies in the fact that the interior use of an enclosed space is changing
frequently due to the. fast changing life styles. What we need today is an' enclosed. space which can adopt to these fast changing needs.
~
Thus tl1eneed of an mterior Designer will increase in the coming years.
. " In India" we are.slowly accepting this fact. In the process, many schools of interior desig-nare started offering dip mas an..

~.'

~

- Most of the students nf interior desigfl are not very clear about the syllabus and method of study. They are attracted to the profession for
the glamour and glossy photographs in magazines. There is no real 'textbook' which can guide the students of intenor design, and this

book tries to meet that desperate need.

I

This book is divided into two sections as Theory and Drawing. The theory part contains History of interior design, Basics of design
composition, Introduction to building materials, Plumbing, Natural ventilation, Air-conditioning, Natural & Artificial lighting, Acoustics,
Building protection, Interior furnishing and information on Indian Institute of Interior Designers. The drawing part contains Lettering &
Scales, Figures & Projections, Building material symbols, Space standards, External & Internal parts, Kitchen design, Staircases, Theory
of colours, Rendering techniques, Three dimensional views and Interior design method. These are the most essential topics and drawing
exercises a student of interior design should learn. I tried to incorporate the latest information available on each subject suiting to Indian
conditions.
I would have included many other topics, but then, it would. become an encyclopedia than a textbook for easy reading and
understanding. However, I welcome suggestions to improve the text in the coming editions from the students and fellow professi~nals
in
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interior design.

M. PRATAP RAO


CONTENTS
THEORY
!
CHAPTER 1. IDSTORY OF INTERIOR DESIGN
. I. Interior decoration as a profession, I
2. Emergence of professional interior designer, I
.

3. Modem interior design features, I
CHAPTER 2. BASICS
OF DESIGN COMPOSITION.
.
I
1. The elements, 3
2. The principles,. 3
3. Golden mean rectangle, 6.
CHAPTER

3. INTRODUCTION

TO BUILDING

1. Stone, 7
2. Clay products, 9

3. Cement. 10
4. Mortar, to
5. Concrete, 10
6. TImber, II
7. Plywood and related products, II
8. Plastics and related products, 12
9. Glass and related products, 12
10. Paints and related products, 13
11. Ferrous and Non-ferrous metals, 13
12. Gypsum and related products, 14
13. Adhesives (or Glues), 14
CHAPTER 4. PLUMBING
1. Water Supply, 15

2. Sanitation,17

MATERIALS
.


2.
3.
4.
5.

Atmospheric conditions for human comfort, 29
Process of air-conditioning, 30
Air-conditioning under lndianclimatic conditions, 30
Types of Air-conditioning methods, 30

6. Refrigeration methods, 32

.

7. Calculation of packaged systems, 32
.

CHAPTER 7. NATURAL LIGHTING.
1. Daylight factor, 33
2. Recommended daylight factors for interiors, 33
3. Calculation of the openings for natural lighting, 34
4. Guidelines for good natural lighting, 36
CHAPTER 8. ARTIFICIAL LIGHTING
1. Different types of lighting arrangements, 38
2. Variety of lamps, 39
3. Lighting accessories, 41
4. Protection devices, 44
5. Calculation of artificial lighting requirement, 45
6. Electrical wiring, 47
CHAPTER 9. ACOUSTICS
I. Properties of sound, 50
2. Sound in interiors, 52
3. Sound absorption, 53
4. Acoustic design of a hall, 55
5. Guidelines for good acoustic design, 56
CHAPTER 10. BUILDING PROTECTION
1. Dampness Protection, 57
2. Tcrmite Protectio~, 60
3. Fire Protection, 61
CHAPTER 11. INTERIOR FURNISHING

1. Ceiling, 63
2. Walls, 64
3. Doors and Windows, 65
4. Flooring, 65
5. Furniture, 68
6. Decorative items, 68
CHAPTER 12. PAINTING INTERIORS
J. Ingredients of paint, 70
2. Types of paints, 70


3. The painting process, 7]
4. Common painting defects and remedies, 72
CHAPTER 13. INDIAN INSTITUTE
A. Rules & Regulations, 73
B. Code of conduct, 78

OF INTERIOR DESIGNERS

DRAWING

73-80

PAGE NO.

1-5

A. LETTERING & SCALES
I. Lettering, ]
2. Scales, J

B. FIGURES & PROJECTIONS
I. Geometrical Figures, 6
2. Orthographic Projections, ]4

6-19

C. ,BUILDING MATERIAL SYMBOLS

20-20

D. SPACE STANDARDS

21

- 22

E. EXTERNAL PARTS
I. Brick Bonds, 23
2. Plan. Elevation and Section. 28
3. Typical Wall cross-section, 30
4. Arches and Lintels, 33
5. Types of Arches, 36

23

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F. )NTERNAL
PARTS
I. Wooden Joints, 38

2. Doors, 42
3. Windows, 46
4. Wooden Panelling, 49
5. Partition Wall, 5]
6. Suspended Ceiling, 53
7. Modular Furniture, 55

38-56

G. KITCHEN DESIGN
H. STAIRCASES

57- 59
60-66

37

1. Dog-Legged Stairs, 6]
2. Spiral Stairs, 63
3. Geometrical Stairs, 65
I.

THEORY OF COLOURS
J. Colour Wheel. 67

67- 75


3. Contrast Colour Scheme I, 72
4. Contrast Colour Scheme I, 74

J.

RENDERING

K.

THREE DIMENSIONAL VIEWS
I. Isometric view, 78
2. Axonometric view, 86
3. Perspective Drawing Principles, 94
4. Perspective (I-point), 95
5. Perspective (2-point), 101

TECHNIQUES

76 :...77
78 - 106

L. INTERIOR DESIGN METHOD
I. Organisation of Space, 107
2. Interior Layout of a Residence, 109

107 -

114

M. INTRODUCTION TO COMPUTER AIDED DRAFING (CAD)
t. Facilities in CAD system, 114
2. Advantages of using CAD, 114

3. Auto CAD (ReI. 10) design software package~ 114

liS -

122



1. INTERIOR DECORATION AS A PROFESSION
The profession of 'Interior Design' did not exist before 20th century. Traditionally the carpenter ,or the store-keeper used to advise the arrangement of
interiors for their clients. Until the First World War interior decoration was closely related to the trade of antiques. The social and economic situation during
the 20th century increased the importance of an interior decorator. Interior decoration still remains a ld?'ury available only to the upper classes of the society.
Certain status is attached in the society in taking professional advise on the appearance of home or'\vork-place. The role of interior decorator is always
advisary because of the consultative nature of the work. It is one of the professions in which women did very well. In America, women tried to establis,h
economic independence through interior decoration of existing buildings or rooms. Interior decorators were mainly responsible for selecting suitable textiles,
floor and wall coverings, furniture, lighting and colour schemes for rooms. Interior decoration never enjoyed the status of architecture and the interior
decorator is rarely responsible for structural alterations. It is regarded as a branch of fashion design because in interior decoration very few schemes remain
.intact for a long time. Interior decoration gained importance with the publication of the book, 'The decoration of houses' by novelist Edith Wharton and
'good taste'
architect Ogden Codman in 1897. They identified the principles of proportion and harmony for the planning of interior schemes. The criteria

~

dominated the profession.

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2. EMERGENCE OF PROFESSIONAL INTERIOR DESIGNER
The status of an interior designer did not improve further due to the Second World War shortages. Then the emergence of interior designer with
,

professionalqualificationstarted to dominatethe interiors.These designersworkedon non-domesticinteriorsbecausethe commercialsector realisedthe
worth of good interior design. During and after the Second World War, modernisation was developed in America. Among the prominent modem architects in
America, Mies Van der Rohe, designed exposed steel-frames and brick-and-glass infills. Different functional areas were delimited by storage units not
reaching the ceiling. Many of the technical innovations of post-war interior design are widely used in the interi~rs.
3. MODERN

INTERIOR

DESIGN FEATURES

Let us discuss some important interior design features in modem buildings. The false ceiling of each floor conceals services such as air-conditioning and
electric cables. They can be easily accessible for maintenance through the false ceiling. The interior working space was opened with rows of desks and small
p~itions replacing corridors and office rooms. The concept of an open-office was developed during the 1950's with large floor areas divided by partitions,
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d~sks, filing cabinets and plants. The working environment is totally controlled with air-conditioning and artificial lighting. The natural elements are
introduced with floor carpets, indoor plants and the use of sky lights. Another interior design feature is to leave interior brickwork and concrete exposed. New
t~hniques for moulding and glueing plywood were discovered by American manufacturer~ during the War forth~ Navy. Th~se. are used for furniture design
hke plastics with fibre-glass reinforcements, plastic shell chairs on metal legs, wire chairs, stacking plastic chairs. bent plywood chairs and black leather


INTERIOR DESIGNS PRINCIPLES AND PRACTICE

2

upholstery. Open shelving, drawers, cupboards and desks replaced partition walls. Thus a good interior design was defined as 'items in which the design was
simple of good proportions and without dust collecting features with stress on good construction'. Manufacturers were allowed to produce their own designs
and there was public demand for ornament and periodic design features. Certain features of modem interiors are indoor plants, built-in furniture, animal skins
as floor coverings, Venetian blinds, open storage space and smooth organic forms. There is a tendency to use different textures and patterns. Free-standing

lamps replaced wall and ceiling lamps. The garden is integrated with the living space by a sliding glass door. The discovery of new building materials led to
many more innovative interior design concepts.

EXERCISE
1. Describe the emergence of professional interior designer?
2. What are the important features of modem interior design?


The main source of design has been nature for man and his creations. From nature many aspects has been picked up for various designs.. To communicate
these thoughts, there is a need to develop a design language. Broadly we can divide them into two groups.
.

.

t'

These are basically visual components used in creating an object or a composition. They can be classified into:
.
(B) Form
(A) Line'
.(D) Colour
(C) Texture
(E) Pattern
(F) Light

.

2. THE PRINCIPLES
These principles help us in determining an object, whether it is artificialty good or bad in appearance. They can be classified into:

(A) Balance

(B) Emphasis

(C) Rhythm
(E) Unity or Harmony

(D) Proportion

Let us discuss t~e 'Elements' in detail

'

,
'

1. A. Line - Line is the basic design element. Too many lines of different nature in a room create an impression of visual chaos like too many beams,
panelling on walls etc., Lines should be restricted to the minimum. Equal heights in furniture bring in the impression of unity in the space. Vertical lines
create the imPression of height and similarly horizontal lines create the impression of more length. Vertical lines of door ways, draperies, windows, built-in

cupboards give strength and height to a room. Similarly horizontal lines are obtained by tables, chairs, book cases etc.,
1. B. Form It is also referred as shape, area or mass. Forms are closely related to lines.,Forms unite with lines to achieve overall design of a given
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.:..

space. A long rectangular table or sofa helps in creating a line of unity in the room but at the same time too many shapes or formS of furniture create the

impressionof chaos.
1. C. Texture - Surface characteristics of any object is known as texture. Text~aJ surfaces range from smooth to rough. A rough texture absorbs light

,

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4
and smooth surface reflects light. Small and dark rooms should have smooth texture and large rooms can have rough texture, if needed. Textures can be used

for wall finish, woodwork, furniture etc.,

1. D. Colour

.

- We react

emotionally to different colours in different ways. Our national flags and political party flags are good examples of our
attachment to various colours. We all know that colours are an integral part of our religion and culture, so the choice of colour is very important and relative
to the functional use of space. Light is intimately linked with colour because light is the source of all colours in nature. Bright colours should be used in dark
areas and dark COIOurfcan be used in lighted areas. There are wide variety of colours for interior surfaces. A careful and thoughtful use of colours is very
essential for attractive interiors.
1. E. Pattern - Pattern is a kind of surface enrichment. Any room will look dull without any pattern. In interior design there are three types of motifs or
units of design.
(a) Naturalistic motifs, which look like picture of flowers, fruits, animals or scenes.
(b) Stylised motifs, which depend upon the material as well as purpose of the article. Ferns and leaves are the most commonly used pattemmodels for
fabrics and other decorative articles.
(c) Geometrical motifs, which are based on forms of circle, rectangle, triangle etc., Stripes, dot and checks are the most commonly seen geometrical
.

motifs in interiors.

.

1. F. Light - Light is an art and utilitarian element. Light is closely related to colour and texture. Daylight is very important in the overall appearance of
a room. Artificial lighting has become common in interior design today due to the lack of natural light in the interiors. There are many reasons for this. Many
designers prefer artificial light for dramatic effect of interiors. However a good combination of natural and artificial lighting will save energy consumption.
Artistic placement of lights can bring out important areas and keep subordinate areas in shadow. There are several types of artificial lighting appliances
available today for interior designers.
Now, let us discuss the 'Principles'
2. A. Balance - Balance is
equalisation of attraction on both
sides of the centre. There are two
types of balance.
(a) Symmetrical or Formal When articles of equal
weight are placed on each
side of the centre and at
equal distance from the
centre, then it is called as
symmetrical
or
formal
balance.
(b) Asymmetrical or InformalIf each side of balancing
point is ditferent and there
is no centre line whichdivides
the composition
into two equal parts, t.l)en it
is called as asymmetrical or
informal balance.

in detail


5
2. B. Emphasis - Emphasis helps to centre the interest to the most important thing or spot in any arrangement. It should be called as focal point or cenVe
of interest. If there is one main emphasized point in a room then others will become subdued. Few examples are a window, an arch. a painting and a furnitUre
piece. The point of emphasis should be decided by the interior designer.

Fig. 2.3. Emphasis

2. C. Rhythm - Rhythm is the movement of the eye' across a design. It is a kind of organised movement in continuity. Rhythm develops through
repetition of shapes, lines or colours.

Fig. 2.4. Rhythm

2. D. Proportion - Proportion is the consideration'of weight. shape and division of an object. It demands that all space divisions should be pleasingly
related to each other. For example the division-of a room (4.0 x 6.0 m) as shown below.


6
2. E. Unity of Harmony - When all the elements of design are nicely related, then the design has unity or harmony. For example if all items have same
colour or similar type of wood or. similar furniture design or similar fabric design. All forms, lines, textures and colours should be harmonious. The colours
need not be the same always, but they can be complementary or matching one another.
J.

\J'Jl.J1..1r..l.,

lUr..ftl.,

~L\.-lftl"'\JLL

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The proportional system most associated with Greek architecture and design, and with classical architecture as a whole is called the 'Golden section or
Golden mean'. Gold is the most uncorruptable and perfect of all the metals, so similarly this propotional relationship is also believed to be perfect. It can be
described as the relationship of two unequal parts, where the ratio of the smaller part to the larger pan is the same as that of the larger part to the whole. The
ratio can be approximately assumed as 1:I.6~ It can also be wriuen algebraically. Assume 'a' as the..maller unit and 'b' as the larger unit, then the relationship

. can be expressed as below

"

-.......

A G()lden mean rectangle can be generated from a given square. First the square is divided into half, then the diagonal of one of these rectangles is
rotated d6wn along the side of the original square. From the end of the rotated diagonal the desired Golden mean rectangle is constructed.
Example:
Assume a square of 4.0 x 4.0 metres.
*
Draw a square of ABCD 4.0 x 4.0 m. in any convenient scale.
*
Divide the square into two equal parts of A~D and PBCO.
*
of OB and calculate its length based on the formula OB
I * Draw a diagonal
.
It is 4.47 m.
Draw the diagonal arch OB cutting at F.
*
Calculate area of larger part (b) or ABCD. It is 16 sq. m.

*
Calculate area of smaller part (a) or BEFC. It is 9.88 sq. m.
*
Add the areas of (a + b) or ABCD + BEFC..It is 25.88 sq. m.
*

EXERCISE
1. What are the elements of design composition?
2. What are the principles of design composition?
3. What is 'Golden mean rectangle' ? Descri~ with an example 'J


Buildings are made of different kinds of mat~rials. It i~ very important to know thes~ building materials. The knowledge of different building materials,
their properties and uses help in achieving economy and efficient use of materials. The cost of materials in the construction of a building ranges from 60 to
70 percent of the total cost. Some essential building materials are described below. Many new building materials are combinations of these materials or
further innovations of these materials. However, there are many other new building materials in the market, so it is also necessary for the Interior Design~ to
.
get acquainted with them for creative interior designing.

1. STONE
There are many varieties of stones available in nature. They can be broadly classified as below:
(A) Different types of stones
(a) Sand stone
(b) Lime stone
(c) Slate
(d) Marble'
(e) Granite
if) Basalt
(g) Laterite
(a) Sand stone - It is very easy tp dress and work. It is extensively used in general ,building cQnstruction and ornamental carving.

(b) Limestone - Lime stone slabs are used for floor41g, paving and roolmg. It is also used for general building purposes and manufacturing of lime.
(c) Slate ~ Slates are used as a roofmg and flooring material. Harder slates are used fot damp-proofmg and steps of staircases.
(d) Marble -'- It is extremely suitable for ornamental and superior type of building work. It is also used for flooring and other decorative works.
(e) Granite It is very hard and durable stone suitable for bridge abutments, piers etc., It is not suitable for carving.
(j) Basalt - It is hard and compact and hence very expensive to wor~. It is used in foundations of structures and superstructures also, but not used for
ornamental work.
I
(g) Laterite - It is normally used for inferior type of stone masonry work.
B. Stone aggregate - Aggregate is a general term applied to all inert materials which when bonded together with cement form concrete.
C. General properties
(a) A good building stone should be hard, tough, compact grained and unifonn in texture and oolour.

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INTERIOR DESIGNS PRINCIPLES AND PRACTICE

8

(b)
(c)
(d)
(e)
(j)

Stone absorbing less water is stronger and more durable as it will have less action of rainwater.
Stone should be properly seasoned by exposure to the air before they are put in a structure.
They should be small enough to be lifted and placed by hand.
Length should be three times of the height and breadth, and it should not be less than six inches. Maximum height should be one foot.
All stones should be wetted before use.

D. Stone masonry types
(a) Random rubble masonry
(b) Coursed random rubble masonry
(c) Square rubble coursed and uncoursed masonry
(d) Ashlar
(a) Random rubble masonry - The stones are hammer dressed on the face, sides and beds to such an extent that the stones will come into close proximity
with the neighbouring stones.

Fig. 3.1. Random Rubble Mason!)' (Uncoursf'.d)

(b) Coursed random rubble masonry - Stones are hammer dressed on the bed and LOPsurfaces until the stones give parallel faces. No face stone should
'''be narrower or shorte.r than its height.

Fig. 3.2. R~dom

Rubble Masonry (Coursed)

(C) Square rubble coursed and uncoursed masonry - Stones should be hammer or chisel dressed on all beds and joiilts so as to make rectangular shapes.

Fig. 3.3. Square Rubble Masonry (Uncoursed)

Fig. 3.4. Square Rubble Masonry (Coursed)


INTRODucnON

9

TO BUILDING MATERIALS

(d) Ashlar - Every stone should be chisel dressed on all beds and joints to be true and square giving perfectly vertical and horizontal joints with the
adjoining stones.

Fig. 3.5. Ashlar

2. CLAY PRODUCTS
The different varieties of clay products are:
(A) Bricks
(B) TIles
.
(C) Terracota
(A) Bricks
The manufacturing of bricks involves four distinct operations. They are earth preparation for bricks, moulding, drying and buining. The

-

normal sizes of bricks available in India are 9" x 4
(a) Brick properties

--

r

x 3" and 10" x 5" x :

The surface should not be too smooth because mortar will not stick to it.
*
A brick should give a metallic ring when struck with a small hammer or another brick.
*

A good brick should not break when struck against another brick or ,,,hen dropped flat from a height of about four
*
to five feet.
* It should have a surface so hard that cannot be scratched by fingernail.
All bricks should be soaked in water for about one hour before use.
*
(b) Bricks are extensively used for construction of building exteriors and interiors in India.
(B) TIles - They can be divided into two classes.
(a) Common tiles used for rooImg, paving and draining,
(b) Encaustic tiles used for decorative purposes,
(c) Properties of tiles - TIles are made more Dr less in the same manner as bricks but they are.made thinner for the sake of lightness and width wise
larger so that the number of joints may be reduced.
(d) TIles can be classified into:
1. Flooring tiles
2. RooImg tiles
3. Quarry tiles.

4. Glazedearthenwaretiles

,

1. Flooring tiles - The tiles should be uniform in size, shape and free from irregularities such as twists, bonds, cracks and laminatio~. Square tile siZes
are 15 x 15 ems with 18 mm thickness, and 20 x 20 cms with 20 mm thickness:2. Roofing tiles - There are number of vaqeties.of interlocking type roof tiles used for sloped roofs and have been patented by some companies. These
are generally rectangular in plan. For example Mangalore tiles, Allahabad tiles, flemish tiles and country tiles.


INTERIOR DESIGNS PRINCIPLES AND PRACfICE

10

3. Quarry tiles - These are very dense and possess a good wear resisting property. They are used for heavy wear or chemical resistance flooring.
4. Glazed earthenware tiles - The top side of the tile should be glazed and the underside should be completely free from glaze so that the tiles may stick
well to the surface. The edges should be free
from glaze. These are generally used in finishing floors and walls of kitchens, bathrooms, water closets and
.

hospitals,wherecleanlinessis important.
5. Terracota - It is a kind of earthenware made from superior clay by burning. Hollow terracota blocks are used as a substitute for stone in ornamental
parts. Porous terracota is a fire resisting material.

3. CEMENT
The best variety of artificial cement is known as 'Portland Cement' or 'Ordinary Cement'. It mainly consists of three ingredients lime, silica and alumina.
Lime 60 to 65 percent and silica 20 to 25 percent. give the required strength, alumina 4 to 8 percent for quick setting and rest 2 to 16 percent are meant for
hardness and colour. Manufacturing of dment by wet process can be-divided into three stages..First stage is mixing of raw materials, second stage is burning
and third stage is grinding. There are other varieties of cement apart from portland cement, they are as described below:
(A) Rapid hardening cement - This type of cement attains high strength in early days because of increased lime content in composition and bumingat
higher temperature and finer grinding. This type of cement is used in concrete when earlyhigh strengths are needed either to remove form work quickly or
speedy construction or in cold weather conditions to reduce the period of protection against low temperature or to achieve economy for early higher strengths.
(B) Quick selling cement - This type of special cement starts setting within five minutes of water addition and becomes bard like stone within thirty
minutes. This is produced by adding small percentage of aluminium sulphate as an accelerator and also by reducing percentage of gypsum and fine grinding.
This type of cement is used where the work has to be completed in a short time. For example cement concreting in static or running water.
(C) White cement - This is a variety of ordinary cement and prepared from such raw materials which are practically free from iron oxide. It is more

costly and used for architectural decoration purposes.
I(D) Pozzalona cement- Pozzalona is a volcanic powder found in thermal plants. It is mixed with cement clinker to prepare cement. It is used for ~
structures, sewage works and other underwater works. This can also be used for internal plastering for economical building construction.
4. MORTAR
It is a mixture of binding material (like cement and lime), fine aggregates (like sand) and water. This is used to bond masonry or other structural units.
The uses of mortars are as mentioned below:
To unite bricks or stones in the construction of brick and stone masonry.

*
To form an even bed between different courses of masonry.work and to distribute the load evenly on the layers.
*
To hold stone aggregate together and form a solid mass of concrete.
*
To cover exposed surfaces of walls and joints with plaster to provide smooth and hard surface.
*
(a) Different varieties of m~rtar
mortar - It is a mixture of lime, sand and water. Lime acts as a binding material for preparing mortar when it is to be used in masonry work.
Generally lime to sand ratio is 1:2.

lime

*

Ce"rent mortar - It is a mixture of cement, sand and water. Where cement acts as a binding material. The proportion of cement to sand varies from
1:2 tC' 1:6 depending upon the desired strength.
Surkhi mortar - It is a mixture of lime, surkhi and water. Here sand is substituted by surkhi for economy and strength. Surkhi is a form of finely burnt

*
*
.

clay.

..5. CONCRETE
It is the most versatile material for all types of construction. It is mainly used in building construction for foundations, columns, beams, slabs, staircases,
lintels, sunshades, door & window frames, storage water tanks etc., There are many varieties of concrete. They are:

/

INTRODUCfION

TO BUILDING MA'JERIALS

11

(A) Plain cement concrete,
(B) Reinforced cement concrete
(C) Prestressed concrete
(D) Lime concrete
(E) Reinforced brick concrete.
(A) Plain Cement Concrete - It is a mixture of cement, water and aggregate. It has high compressive strength. It has good workability as it can be
moulded into different shapes. It has high durability value and not much affected by atmospheric conditions. It is a good insulator and has a fairly good fire

resistance.

.

(B) Reinforced Cement Concrete (RCC) - In reinforced cement concrete, both concrete and reinforcing metal (usually steel) are combined to act together
as one material and produce a more economical material than either acting alone. A general proportion of mix is 1:2:4 for general work.
(C) Presttessed Concrete - This is a modification over RCC in which steel provides high initial compressive stresses in the concrete so that it may resist
tensile stresses without cracking. Prestressed concrete saves upto fifty percent of concrete and quantity of steel is also reduced as high
tens.!!~ steel is used.
(D) Lime Concrete - It is a mixture of lime, fine and coarse aggregates and water in 1:2:4 proportion.
(E) Reinforced brick Concrete - It is known as RBC. In reinforced brick concrete, steel rods are embedded inrement concrete which take teJlSion

whereas compression is.taken by brick. This is cheaper than RCC.

.

6. TIMBER
Timber is that part of wood of a tree which is of sufficient size and can be used for builQing, carpentary and various other construction purposes. Some
trade names of timber available in the market are Babul, Deodar, Teak, Sal and Walnut. Timber is available in different forms. They are:
Converted timber, which is sawn and cut into suitable commercial sizes.
*
j Rough timber, which is ?btained after falling a tree.
* Standing timber, which is available in a living tree.
(A) Properties of good timber
Timber should have sufficient weight. A timber with heavy weight is considered to be sound and strong.
*
The structure of timber should be uniform, hard and compact.
*
It should have favourable physical characteristics such as dark colour, straight fibres,. and shining appearance. It should be free from defects and good
*
sound rSl10UIdemit when struck.

(B) Seasoning of timbers

.

This is the process of drying of timber in order to remove all the plant juice and moisture out of it so that it will not decay. Seasoning of timber may be
done naturally- or artificially.
.
(C) Preservation of timber
It is the process of preserving the timber structure from the attack of destroying agents like moisture, fungi and insects to ensure increased life. Some of
the preservatives used are oil paints, coal tar and chemical salts.
7. PLYWOOD AND RELATED PRODUCTS
Timber, which is scientifically prepared in factory to meet the desired shape, appearance, size and strength is termed as 'industrial timber'. Industrial

timber is available in various varieties such as veneers, plywoods, laminated timber and block boards. Such varieties are:
(A) Plywoods
(B) Fibre boards
(C) Block boards


12

INTERIOR DESIGNS PRINCIPLES AND PRACTICE

Veneers are thin sheets or slices of wood of superior quality, which are knife cut by various processes. Thickness varies from 0.4 to 0.6 mm or even
more. Veneers are used to produce plywoods, batten boards and laminated boards. This process is known as veneering.
(A) Plywoods - These are prepared by cementing together thin boards or sheets or'wood into panels. Three or more veneers, which are always odd in
numbers are placed one above the other so that the grain of each layer is at right angles to the grain in the adjacent layer. The main advantage is uniform
strength and greater resistance to cracking and splitting with change of moisture content. The veneers are held by suitable adhesives like synthetic resms.
They are available in standard sizes and thickness. It is used for interior partitions, doors and panelling.
(B) Fibre boards These are rigid boards, which are prepared after processing pieces of wood, cane and then pressing them together. It is also known as
pressed wood and available in various forms like laminated boards and hard boards. They are used for wall panelling, suspended ceiling and partitions.
(C) Block boards - Block board has a core made up of strips of wood glued or joined to form a slab, which is further glued between two or more outer
veneers in such a way that direction of the grain of the core blocks running at right angles to the adjacent outer veneers. These boards are Qf two types,

-

.

commercial and decorative. It is used for furniture, panelling and partitions.

8.PLASTICSANDRELATEDPRODUCTS

,..

\

Plastic is an organic material of high molecular weight, which is soft enouglf at some stage of its manufacture to be formed in various shapes by aptftymg

beat and pressure. Plastics are broadly classified into different types depending upon their behaviour when heated and cooled during manUfacture.
(A) Thermoplastics - These plastics are softened by heat during the manufacturing process and regain their original properties as they solidify duriQg
.

'

cooling to form the fInished product. Some of the uses are PVC tubes, wall tiles, floor tiles and glazing.
(B) Thermosetting plastics - These plastics change chemically when heated during manufacturing. They solidify while still hot and assumetli~'iQrii1 of
finished product. It is not possible to reshape these plastics by means of heat and pressure. Some of the uses are Wash basins, water closets, vMves,haIidles
and wall panels.
'~
9. GLASS AND RELATED PRODUCTS
Glass is a mixture of number of metallic silicates like pure sand, soda, chalk and one of which is usually an alkali metal. Various varieties.~
developed in recent tiiI}es. Some of them are:

gi~are


INTRODUCfION

13

TO BUILDING MAlERIALS

10. PAINTS AND RELATED PRODUCTS

Paints.are the coating of fluid materials applied as a final finish to all surfaces like walls, ceiling, woodwork and metal work.
(A) Characteristics of a good p~int
(a) It should possess good spreao~g or covering power.
(b) It should be cheap and economical in the long run with easy applicability and drying capacity within a day.

(B) Types of paints

.

(a) Aluminium paint - This paint c~sists of finely ground aluminium suspended in varnish and ~ evaporation of varnish spirit or oil, the particles of
aluminium form a thin coating on the surface. It is used for metal roofs, gas tanks, eledtReal and telephone poles and machinery.
(b) Anti-corrosive paint - It consists of oil, a strong drier and a pigment mixed with fine sand. It gives black appearance to the surface. It is ..sed to

preserve steel work from corrosion.
(c)
Bituminous
and Tar paints - These paints consists of bitumen or tar dissolved in petroleum or spirit. They are alkali resistant and possess high
.
. covering power. They are used for painting steel, brickwork exterior and roofs.
'
.

(d) Cement paints

- This

'

consists of boiled linseed oil into which dry good cement (65 t075 percent) is mixed so that a paint of workable consistency is

obtained. Cement paint is available in powder form in variety of shades. It has Ibetter water proof qualities, strength, hardness, durability and
decorative appearance. It is used for p,lastered brickwork, stone masonry and concrete. It lasts minimum five to six years before renewed painting is
~~
Emulsion paint - This paint consists polyvinyl a~etate, synthetic resins etc., giving excellent quality of alkali-resistance. It has good workability, high
'

(e)

,

"

durability and quick drying. It is used for masonry surfaces.

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.
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if>Enamel paint - This paint consists of metallicoxide ground with a small quantityof oil and mixed with petroleumspirit for holding the paint
together. It is available in ready made form in variety of colours. It dries slowly but after drying it forms a smooth surface. It is not affected by hot

and cold water and steam,and it is easilywashable.It is used both for internaland externalworks.
(g) Oil paint

- This

,

is the ordinary paint. The oil paints are used in. general for all types of surfaces such as'wood work, walls, ceilings and metal work.

Three coats like primer, undercoat and finishing coat are necessary for internal work.

'

(h) Plastic paint - It consists of a variety of plastics as the base. When this paint is thinned with water, it is known as 'plastic emulsion paint'. It has

decorative appearance, high covering power and quick drying. They are widely used for showrooms, auditoriums and cinema halls.

'

(i) Distempers - They are considered to be water-paints consisting of whiting or chalk powder, glue as a binder and suitable fast colouring pigments.
These are cheap, durable and easily applied on plastered, cement concrete and wall board surfaces.
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11. FE~ROUS

AND NON-FERROUS

-

METALS'

(A) Ferrous metals All such metals containing iron as their main constituent are termed as ferrous metals.
(a) Cast Iron ~ It is ItlaIlufactured by refining pig iron in a cupola furnace. Carbon content in cast iron varies from 1.7 to 4.5 percent It is strong in
,

compression and weak in, tension. It cannot be welded, rolled, puncheq or riveted but caD be melted and cast into various. shapes and rusts slowly. It
.
is used for making builcfu\g column brackets, spiral staircases, manhole covers, ra;.n water pipes and sanitary fittings.

(b) Wrought iron - It is the p1.\re~tform of iron with low carbon content (less than 0.15 percent) It is hard and can be bent, twisted, rusts more quickly

than cast iron. It is replace~ brmild steel at present, so it is produced in small quantity. It is used for making tough materials such as nails, bolts,
chains, sheets, handrails an4 ornamental gates.
"

(c) Steels - Steel is an alloy or compound of irOn and carbon in the form of carbide of iron. The carbon percentage is limited to 1.5. There are three
"

grades of steel in accordance with the percentage of carbon.

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1. Low carbon or mild steel.
2. Medium carbon or hard steel.
,.'

3. High carbon steel."

,

The increase of carbon percentage increases the tenacity and hardness. Steel is used for trusses, beams, griiIs, mechanical devices and sheets.


INTERIOR DESIGNS PRINCIPLES AND PRACflCE

14

(B) Non-ferrous- metals - These are the metals which do not contain iron as their main constituent. They are of several types. Three of these metals are

of important use in building industry.

.

.

(a) Aluminium - It is silvery white lustrous metaIobtained from 'Bauxite' ore. Pure aluminium is very soft and it is mixed with other metals like copper,
magnesium, silicon, manganese and others to increase tensile strength and hardness while retaining the character of lightness and durability. It is
.
corrosion resistant and good conductor of heat and electricity. It is used for roofmg, window frames, glazing bars, posts, panels., wires and in paintS.
(b) Lead - It is bluish grey in colour with silvery lustre when freshly cut and available in free state. It is resistant to atmosphere corrosion and not
affected by soil,. sewage and industrial wastes. It is used for roofmg, water service pipes, cable coverings and ornamental work.
(c) Copper - Copper. is extracted by smelting 'Copper Pyrites' which is an ore of copper. Pure copper is of lustrous red colour, light, tough and good
.
conductor of heat and electricity. It is used for electric wires, cables, roofing and electroplating.
C. Alloys It is an intimate mixture of two or more metals. The properties of an alloy are entirely dim~rent from those of its constituents.

-

(a) Brass

- It is all alloy

of copper and zinc. Commercial brass contains 65 percent copper and 35 percent zinc. Properties of brasses vary considerably

by changing these proportions. It resists corrosion but needs regular cleaning. It is used for door and window fittings, household utensils and
hardware.
(b) Bronze - It is an alloy of copper, zinc and tin containing 80 percent copper. Bronzes are hardened copper. They are stronger and superior to brass in

cOrrosionresistance. It is difficult to work and niore expensive. It is used for frames, grills and hardware.
12. GYPSUM AND RELATED. PRODUCTS
. (A) Gypsum

-

It is a combination of calcium sulphate. with water and the white substance is found in the form of rock in nature. It is mainly used in th~
manufacture of cement to increase its setting time.
.

..

(B) Plaster of paris (POP) - When finely ground gypsum rock is heated to a temperature between 100°C and 140°C, three fourth of the
passes off as a steam. The remaining product is known as 'plaster of paris'. It is used for ornamental work and its products are hard-surfaced,
contours and they are sufficiently strong. Gypsum plaster is rendered more plastic by the addition of clay on hydrated lime. Its cohesiveness
adding
hair or shredded wood fibre.
.
(C) Plaster board - It isa large sheet of gypsum plaster faced on both sides with stout paper as a reinforcement. Depending upon the

.
paper, plaster boards are of two types. They are:
1. Gypsum lath board, when the .facing paper is rough and provide adhesive grip for plaster finish.

combined water
can have sharp
is increased by
.
nature of facing

.

2. Plaster wall board, when facing paper is of self-finish type for decoration. They have good insulation properties and used for ceilings and partitions.
. (D) Asbestos - It is naturally occuring mineral substance composed of hydrous silicates and contains small amount of" iron oxide and alumina. It is
largely uSed for preparing Asbestos Cement, which is used for making pipes and roofing material. Asbestos felt is used as damp' proof layer for insulation and
.
as lining material.
13. ADHESIVES

(OR GLUES)

An adhesive is a substance which enables two surfaces to stick together and behave as a single unit. They are classified into two types:
Organic adhesives are made out of animal blood albumin, vegetables, milk and other organic wastes.
(B) Synthetic adhesives are permanent, strong, water proof and made out of chemical resins.

(A)

EXERCISE
1. Describe the properties and uses of the following building materials:
.
(b) Clay
(a) Stone
(d) Mortar
(e) Concrete
2. Describe the properties and uses of the following building materials:
(€i) Plywood
(b) Plastics
(d) Paints
(e) Metal.s

(c) Cement
(j) Timber
(c) Glass
if) Gypsum


In the present context, plumbing services mean Water supply and Sanitation including sewerage and drainage. The importance of plumbing services is
well known in a building. This knowledge helps an Interior Designer to plan the interiors efficiently keeping in view of these service requirements.
1. WATER SUPPLY
..

A. Water supply in residential buUdings
Public water supply system consists of collection, conveyance, treatment and distribution. Water is distributed for consumption in a building through
internal water distribution system. Water supply in a building depends on the size :md height of the building. Large and tall buildings create numerous


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16

INTERIOR DESIGNS PRINCIPLES AND PRACTICE

installation and design problems, whereas in low rise buildings they are not found. Water piping system may be basically horizontal or vertical. Systems
above the .main or pressure tank are called upfeed systems. In tall buildings water is pumped to elevated tanks, so that it can flow down. Adequate water is
needed for drinking, fire protection and general use. Before designing a building water requirement should be calculated keeping the present and future needs
of the 9ccupants. Availability of sufficient quantity of water sources like municipal water, ground water and surface water should be found. Normally
municipal water is treated and supplied, whereas ground and surface water should be properly treated as per the need . of the users. Distribution of water is

done"with pipes internally in a building.

'Residential buildings are nOrmaHy-ooe-- t~pipe. A water meter is connected to the service mm. Once the service pipe emerges from the floor level of the building, it is referred as the rising main. The
s(:rvice pipe can supply to upper floors depending upon the available water pressure. If adeEluate pressure is not available, then water can be collected in a
sUmp, which can be constructed below the ground floor level and pumped up to the elevated water tanks with a motor. From these tanks, water can be
distributed down with gravity pressure. Water storage tanks located on the terrace should be properly covered and protected from contamination. Plastic water
, tanks are preferred for storage pU1Jl..ose.
'
B. Water supply in multi storeyed buildings
Water supply pressure from the main will not be sufficient to reach the upper floors on many occasions, so it is necessary to pump it to reach the upper
floors. The water requirement in such buildings is very high for both drinking and general use. Thus there is a need to store water and supply it with gravity
pressure. The storage of water is possible only on the terrace of the building. Pumping of water from the main becomes a necessity, but continuous operation
would be costly and difficult to maintain. To avoid this, storage techniques are employed to prevent continuous pumping. Most common storage systems used
are:
(a) The header storage system
(b) Enclosed tank system
(a) The header storage system - In this system, water is pumped through the rising main to the terrace of the building, where two storage tanks are
placed. One is meant for drinking water, and the overflowing water from this tank is connected and collected in another storage tank for general use.
The storage capacity of the drinking water tank is calculated as 5-7 litres per dwelling unit in the case of residential buildings. The storage water is
supplied with gravity pressure.in separate pipes for drinking and general use.
(b) Enclosed tank system - Normally drinking water is directly taken from the main because storage can lead to contamination and bad taste. However,
storage of drinking water is inevitable due to various reasons for daily use. So it should be stored in an enclosed, insulated and ventilated tanks to
avoid contamination and bad taste. There are two common storage systems adopted for this purpose. In one system, two separate tanks are located
for drinking water and general use at .the ground or basement floor level. The capacity of the tanks at the roof level can be dwelling unit-wise or
floor-wise or one for all the dwelling units. This calculation depends on the space and convenience. In another system, a large tank is located in the
.

ground or basement floor to supply both drinking water and general purpose water. From this tank, water is pumped to the roof level for storing
separately for drinking and general use. From these storage tanks, water is supplied by gravity pressure in separate pipes for drinking and general
use.mfuth the systems wider is pumped to the roof level with motor.

C. Piping materials
Cast iron, steel, concrete and asbestos cement are the most common materials used in distribution pipes. Copper, lead, Zinc, brass, bronze and plastic are
used in small pipes, valves, pumps and 'other appurtenances. Common pipe joint materials are lead, cement, sand, rubber, plastic and sulphur compounds.
Stoneware pipes are mostly used for underground work. Cast iron is the most common material for city water mains. Steel is commonly used for large
pipelines and trunk mains but rarely used for distribution mains. Concrete pipes may be precast in sections and assembled on the job or cast in place. Hume

.

.pipes are RCC pipes used for drainage,irrigation,wells and culverts.Galvanisedpipes of steel or wroughtiron are widelyused for distributionsystems.
Thes~ pipes are used where pipes are to be exposed to corrosive conditions such as salt water or air. Lead pipes are not generally used for domestic water
supply. They can be used for flushing and overflow pipes inside the buildings. PVC pipes are more flexible, conosion resistant, light weight, easy to handle
and install. It is comparatively cheaper. They are not suitable for hot water installations.


2. SANITATION
Water after usage becomes waste water, which should be collected and conveyed through drain pipes to join the municipal sewers laid under the roads.
The surface and rain water is also let into the sewers in the combined drainage system. The waste water is let into the municipal sewers through underground
chambers like manholes connected by traps like gully trap, intercepting trap, grease trap, silt trap and ventilating pipes. The primary function of the trap is to
seal the foul air entering the building.
A. Traps
Traps prevent entry of foul gases and odour from municipal sewers and drains. Depending on the need, a water seal is created as a barrier. The depth of
the water seal can be between 35 rom to 75 rom. These traps should be created as close to the unit as possible. Efficiency of the water seal depends on the
depth of the water. Traps should be made of non-absorbent material. Entry inlet into a drain should be properly trapped with a water seal. It should be
provided with a cap or plug for cleaning. Traps can be made of different shapes. Most conimon shapes of traps are p. Q and S. (See Fig. 4.1,4.1.2, 4.1.3)
(a) Gully trap'- Gully traps disconnect the sullage drain of the house from the main drain. They are employed to receive sullage or waste water from
wash basins, sinks and baths and pass it on to the house d'mns. Gully traps should be fixed near the surface level of the flOQr.There should be a


grating on top of the tiap to block solid matter. Pipes should be connected to the gully trap below the grating. In combined system of sewage the rain
water is also passed into the house drains through the gully traps. (See Fig. 4.1.5).

(b) Intercepting Trap - It is also known as 'sewer'trap. It disconnects the house drain from the street sewer. It can be fixed in the last manhole of the
house or in a separate small chamber between tbe lowest end of the house drain and the street sewer. It has a comparatively deeper water seal than
ordinary trap and an opening at the top of the trap known as 'cleaning eye'. This opening is closed with a plug. The intercepting traps should be
properly flushed out otherwise they wilJ not be of much use. (See Fig. 4.1.4).
(c) Grease trap - Grease traps are used where large quantities of oily wastes are let out into the drain like hotels, restaurants and some industries. These
oily substances deposit solids in the house drains and municipal sewers. To avoid this, grease traps are used. Grease trap can be a small cast iron or
masonry chamber with a bent pipe as on outlet. The oily substances float to the surface to form a scum on top. The bent pipe allows the sewage to
flow out while retaining the scum. This scum cari be removed out from the top. (See Fig. 4.1.6).
(d) Silllrap - Washing of kitchen utensils, sometimes, involves ash and pulverised brick pieces. These particles need steep slopes and higher velocities

.