Unit 2

Basic Civil Engineering
( Subject Code: 1150CE101 )
Lecture Slides
By
Department of Civil Engineering
Vel Tech Rangarajan Dr. Sagunthala R&D Institute of Science and Technology
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Syllabus
UNIT I: Building Materials
Introduction – Civil Engineering – Materials – Bricks – Composition – Classifications – Properties – Uses – Stone – Classification of
Rocks – Quarrying – Dressing – Properties – Uses – Timber – Properties – Uses – Plywood –Cement – Grades – Types – Properties –
Uses – Steel – Types – Mild Steel – Medium Steel – Hard Steel –Properties – Uses – Market Forms – Concrete – Grade designation –
Properties – Uses – Advancements in Concrete – Pre-stressed Concrete – Pre fabricated concrete.
UNIT II: Building Components
Building – Selection of site – Classification – Components – Foundations – Functions – Classifications – Bearing Capacity – Flooring –
Requirements – Selection – Types – Cement concrete marble – Terrazzo floorings – Roof – Types and requirements.
UNIT III: Planning Aspects and Regulations
Building types and design criteria – Space standards for residential, commercial and institutional categories – Building by-laws
applicable for approval by the local governing body – Development control rules for Chennai Metropolitan Area. Basic guidelines for
earthquake resistant structures.
UNIT IV: Water Supply and Sanitary Systems
Water supply – Objectives – Quantity/Quality of water –Sources – Standards of drinking water – Distribution system –Sewage –
Classification – Technical terms – Septic tank – Components and functions – layout of external services –water supply – Sewage
disposal – water supply and plumbing layout for a residential building.
UNIT V: Surveying and Transportation
Surveying – Objectives – Classification – Principles of Survey – Transportation – Classification – Cross section and components of
road – Classification of roads – Railway – Cross section and components of permanent way – Functions – Water way – Docks and
Harbors – Classification - Components – Bridges – Components of bridges.
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Unit II: Building Components
Building – Selection of site – Classification – Components – Foundations –
Functions – Classifications – Bearing Capacity – Flooring – Requirements –
Selection – Types – Cement concrete marble – Terrazzo floorings – Roof – Types
and requirements.
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Building
4
“A building is any structure
enclosing a space and provided with
roof. Such a structure may be
meant for people to live (or) to
provide working space for offices
(or) to accommodate machinery
(or) to store materials or any
purpose”

Building
A building has to be planned in such a manner that it is comfortable and pleasant for living. Building meant for
offices, factories, etc. should be planned to provide a healthy environment offering good light, ventilation, drainage
and good water supply connections.
Some of the requirements of a building are as follows:
(i) A building should not be affected by atmospheric conditions
(ii) A building should be strong enough carry safely all the possible loads that are liable to act on it.
(iii) A building should be planned to prevent entry to moisture
(iv) A building should have good ventilation
(v) Doors and windows must be properly located to afford good lighting without causing glaring.
(vi) A building should be constructed so as to be safe against fire hazards.
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Site Selection
I. Site Selection for Residential Buildings: The selection of site has an important
bearing on the planning as well as designing of building. A building has to be planned
based on the location and geometry of the site.
The following points may be given due consideration while selecting a site for a
residence:
(i) The site should be preferably in a well developed or a rapidly developing locality
(ii) The neighborhood should be civilized and sociable
(iii) General facilities like water line, sewer line, power line, street lighting should be
available.
(iv) The site should be easily accessible by roads.
(v) The soil condition should be satisfactory. Hard rock or good compact soil should
be available at a depth of 1metre.
(vi) Quarries, Kilns, factories etc. should not be close to the site. 6

Site Selection
II. Site Selection for Industrial Buildings: Industrial buildings are meant
for production assembly, fabrications, etc. A site for an industrial building
may be selected on the following considerations:
(i) The site should be at a good distance from congested localities. Then
only there will be scope for future expansions.
(ii) The site should be near the source of raw materials needed for the
industry.
(iii) Due to utilization of large quantity of water, it is very necessary that the
site should be at a raised level facilitating easy drainage of wastewater.
(iv) The site should be easily approachable by road and rail.
(v) Enough power should be available. An industry can run only if there is
continuous and adequate power supply.
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Classification of Building
According to National Building Code (1970), the buildings are classified based on:
I. Type of Occupancy
II. Type of Construction
III. Fire Resistance
I. Based on Occupancy
(i) Residential Building: These include any building in which accommodation is provided for normal residential
purposes, with or without cooking and dining facilities. For eg. Houses, lodges, apartment houses.
(ii) Educational Building: These include any building used for schools, colleges, Universities, etc.
(iii) Institutional Building: These include any building which is used for treatment purposes. Hospitals, Clinics,
houses for aged and infants, Jails, etc. comes under this category.
(iv) Assembly Building: These include any building where a group of people gather for recreation, social, religious,
patriotic and similar purposes. Cinema theatres, gymnasiums, railway stations, stadiums etc. comes under this
category.
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(v) Business Buildings: These include any building which is used for the transaction of businesses. Offices, bank city
halls, courthouses and libraries comes under this category.
(vi) Mercantile Buildings: These include any building which is used as a shop, stores or markets for display and sale
of merchandise either wholesale or retail.
(vii) Industrial Buildings: These include any building in which products or materials of all kinds and properties are
fabricated, assembled or processed. Laboratories, dry cleaning plants, power plants, sawmills, etc. comes under this
category.
II. Based on Construction:
(i) Load Bearing Wall System: Raising the house, wall over wall and floor over floor, has been the most common
method all over the world. In this system, the load is supported and transferred to the foundation through the
masonry walls and there are no concrete structural elements, like columns or beams to support the load.
Therefore, the walls must be strong enough for the purpose and are usually 9 inches or more in thickness.
(ii) Framed System: Also known as column-beam structure has a combination of beams and columns to support and
transfer the load. The roof load rests on the beams, the beams transfer the load to the columns, which in turn
transfer the load to the foundation. In this system, the masonry walls are not subjected to any load. Frame
structures are preferable to load bearing wall structure in the construction of large and multi-storey buildings.
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Load Bearing System
Framed System

III. Based on Fire Resistance:
(i) Type I: Buildings those provides 4-hour fire resistance
(ii) Type II: Building those provides 3-hour fire resistance
(iii) Type III: Buildings those provides 2-hour fire resistance
(iv) Type IV: Buildings those provides 1-hour fire resistance
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Building Drawing
(Demonstration)

Components of Building
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A building consists of following basic
components:
(i) Foundation
(ii) Plinth
(iii) Damp Proof Course (DPC)
(iv) Plinth beam
(v) Floors
(vi) Walls
(vii) Openings
(viii) Stairs
(ix) Roofs
(x) Surface Finishes

1. Foundation
A foundation is necessary to evenly distribute the entire building load on the soil in such a manner that no
damaging settlements take place. Hence, the foundations need to be constructed on good/solid ground.
2. Plinth
A plinth is normally constructed just above the ground level and immediately after the foundation. It raises the
floor above the ground level and herewith prevents surface water from entering the building.
3. Damp proof course (DPC)
Damp proof course is a layer of water proofing material such as asphalt or waterproof cement. Walls are
constructed above the damp proof course.
Damp proof course prevents surface water from rising into the walls.
Dampness reduces the strength of the walls and creates unhealthy living conditions. Also it affects the paint and
plaster and increasing the cost of maintenance.
Damp proofing layer is not required where a plinth beam is constructed, because the plinth beam already
performs like a DPC. 18

4. Plinth beam
A plinth beam is constructed depending upon the type of the structure of the building and nature of the soil. It provides
additional stability in regard to settlements of the building and earthquake damages.
5. Floor
This is the surface on which we do most of our activities. Floorings is laid over the filling of the plinth and on
subsequent floors.
Flooring can be done with different materials, but care must be given that the ground below the floor is well compacted.
Flooring is done to prevent dampness from rising to the top and to have a firm platform that can be kept hygienic and clean.
6. Walls
Walls are the vertical elements on which the roof finally rests. They can be made of different materials like bricks,
stones, mud, concrete blocks, lateritic blocks etc. If the walls are very long, columns can be provided to carry the roof.
Walls provide privacy and enclosure. Walls also provide security and protection against natural elements such as wind,
rain and sunshine.
Openings are to be provided in wall for access and ventilation.
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7. Openings
Openings are normally provided in the walls as door, windows and ventilators.
Doors provide access; windows and ventilators provide light and ventilation.
Lintels are constructed just above the openings. It is normally a stone slab or a concrete slab.
Sill is the part of the wall that is just below the window.
Lintels are constructed to hold up the walls above the openings. In earthquake prone areas a continuous lintel beam is
provided all over the walls.
8. Stairs
A stair is a sequence of steps and it is provided to afford the means of ascent and descent between the floors and landings.
The apartment or room of a building in which stair is located is called staircase. The space or opening occupied by the stair
is called a stairway.
There are different kind of stairs are used in buildings, like RCC stair, wooden stair, metal stair, brick stair etc.
9. Roof
The roof provides protection for the building and the people living in it. The roof rests on the walls and requires proper
anchoring so that wind and other mechanical impact cannot destroy it. A roof can have different shapes but it is always either flat
or sloping.
Roof is typically made of RCC, stone slab, tiles etc.
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10. Surfaces / Finishes
External finishes are the outer most layer of protection, which protect the structure from weathering. Internal finishes
are the layers given on internal faces. They give durability and pleasing appearance to the inside.
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Cross Sectional

Foundation
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“The foundation is a structural
component of the building which is
in direct contact with the ground
and transmits the entire load of the
building to the ground”

Functions of Foundation
(i) Reduction of Load Intensity:
Foundation distributes the loads of the super structure, to a larger area so that the intensity of
the load at its base (i.e. total load divided by the total area) does not exceed the safe bearing
capacity of the sub-soil.
(ii) Even Distribution of load:
Foundations distribute the non-uniform load of the super structure evenly to the sub soil. For
example, two columns carrying unequal loads can have a combined footing which may transmit
the load to sub soil evenly with uniform soil pressure. Due to this, unequal or differential
settlements are minimized.
(iii) Provision of Level Surface:
Foundation provide leveled and hard surface over which the super structure can be built.
(iv) Lateral Stability:
The stability of the building, against sliding and overturning, due to horizontal forces (such as
wind, earthquake etc.) is increased due to foundations. 23

Classification of Foundation
Foundations may be broadly classified into the
following two categories:
(i) Shallow Foundation
(ii) Deep Foundation
A Shallow Foundation is the one in which the
depth is equal to or less than its width.
When the depth is more than the width of the
foundation, it is termed as Deep Foundation.
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Shallow Foundation
Shallow foundations are constructed where soil layer at shallow depth (up to 1.5m) is able to support the structural loads.
The depth of shallow foundations are generally less than its width.
In this foundation, the total loads of the structure are distributed over a horizontal area at shallow depth below the
ground level.
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Types of Shallow Foundation
The different types of shallow foundations are:
(i) Strip Footing
(ii) Isolated footing
(iii) Combined footing
(iv) Strap or Cantilever Footing
(v) Mat or raft foundation
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Strip Footing
• A strip footing is provided for a load-bearing wall.
• A strip footing is also provided for a row of columns which are so closely spaced that their spread footings overlap or
nearly touch each other.
• In such a case, it is more economical to provide a strip footing than to provide a number of spread footings in one line.
• A strip footing is also known as continuous footing.
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Isolated Footing
• Isolated footing (or Stepped or pad) footing is provided to support an individual column.
• Isolated footing is circular, square or rectangular slab of uniform thickness.
• Sometimes, it is stepped or haunched to spread the load over a large area.
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Combined Footing
• A combined footing supports two columns.
• It is used when the two columns are so close to each other that their individual footings would overlap.
• A combined footing may be rectangular or trapezoidal in plan.
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Strap or Cantilever Footing
• A strap (or cantilever) footing consists of two isolated footings connected with a structural strap or a lever.
• The strap connects the two footings such that they behave as one unit.
• A strap footing is more economical than a combined footing when the allowable soil pressure is relatively high and
the distance between the columns is large.
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Mat (or) Raft Foundation
• A mat or raft foundation is a large slab supporting a number of columns and walls under the entire structure or a large
part of the structure.
• A mat is required when the allowable soil pressure is low or where the columns and walls are so close that individual
footings would overlap or nearly touch each other.
• Mat foundations are useful in reducing the differential settlements on non-homogeneous soils or where there is a large
variation in the loads on individual columns.
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Deep Foundation
A deep foundation is a type of foundation which transfers building loads to the earth farther down from the surface
than a shallow foundation does, to a subsurface layer or a range of depths.
There are many reasons a geotechnical engineer would recommend a deep foundation over a shallow foundation,
such as for a skyscraper.
Some of the common reasons are very large design loads, a poor soil at shallow depth, or site constraints (like
property lines).
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Types of Deep Foundation
The different types of deep foundations are:
(i) Pile Foundation
(ii) Well (or) Caisson Foundation
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Pile Foundation
A pile is basically a long cylinder of a strong material
such as concrete that is pushed into the ground to act as a
steady support for structures built on top of it.
Pile foundations are used in the following situations:
• When there is a layer of weak soil at the surface. This
layer cannot support the weight of the building, so the
loads of the building have to bypass this layer and be
transferred to the layer of stronger soil or rock that is
below the weak layer.
• When a building has very heavy, concentrated loads,
such as in a high rise structure, bridge, or water tank.
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Types of Pile Foundation
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There are two fundamental types of pile foundations
(based on structural behaviour), each of which works
in its own way.
End Bearing Piles: In end bearing piles, the bottom
end of the pile rests on a layer of especially strong soil
or rock.
The load of the building is transferred through the pile
onto the strong layer. In a sense, this pile acts like a
column.
Friction Piles: Friction piles work on a different
principle. The pile transfers the load of the building to
the soil across the full height of the pile, by friction.
In other words, the entire surface of the pile, which is
cylindrical in shape, works to transfer the forces to the
soil.

Materials for Pile Foundation
Piles can be made of wood, concrete, or steel.
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Construction of Pile
Foundation
Piles can be either cast-in-place or precast driven
piles.
Cast-in-place piles are made in the following
steps:
• Hammer a thin-walled steel tube into the
ground
• Remove all earth left inside the tube
• Lower a steel reinforcement cage into the
tube
• Cast the pile by pouring wet concrete into
the tube
• The thin walled steel tube is called the
casing, and only serves to form a secure
mould for casting concrete that is free from
earth and debris. It has no structural role to
play after the casting is complete.
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Construction of Pile
Foundation
Precast Driven Piles are first cast at ground
level and then hammered or driven into the
ground using a pile driver.
This is a machine that holds the pile perfectly
vertical, and then hammers it into the ground
blow by blow.
Each blow is is struck by lifting a heavy
weight and dropping it on the top of the pile.
The pile is temporarily covered with a steel
cap to prevent it from disintegrating
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Well (or) Caisson Foundation
• Well foundations are also called as Caisson foundation.
• It is box like structure – circular or rectangular that
sunk from the surface of land or water to the desired
depth.
• Well foundation forms the most common type of deep
foundation for bridges in India.
The following components are to be considered while
designing the well foundations. They are:
(i) Well Curb
(ii) Cutting edge
(iii) Bottom plug
(iv) Steining
(v) Well cap
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Well (or) Caisson Foundation
Advantages of Well Foundations:
(i) It can go to large depth
(ii) The cost of construction is low
Uses of Well Foundations:
Caisson or well foundations are used for major
foundation works like:
(i) Break water and other structures for shore
protection
(ii) Wharves, quay walls and docks
(iii) Bridge piers, abutments in lakes, rivers, etc.
(iv) Pump houses that is subjected to heavy
vertical and horizontal loads
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Foundation of World’s Tallest Building

Bearing Capacity of Soil
The maximum load which the soil can bear per unit area without any yielding (or) failure is
called as bearing capacity. Safe bearing capacity is obtained by,
Safe bearing capacity = (Ultimate bearing capacity / Factor of safety)
It is denoted by kN/m2.
Methods for Improving Bearing Capacity of soil:
If the bearing capacity of the soil is very low, the dimensions of the footing should be
very large and will be uneconomical. In such cases, it is better to improve the bearing capacity
of the soil. The following methods are used to improve the bearing capacity of the soil:
(i) Increasing the depth
(ii) Draining the soil
(iii) Compacting the soil
(iv) Confining the soil
(v) Cement grouting
(vi) Chemical treatment.
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Improving Bearing Capacity
(i) Increasing the depth:
• For sandy soils, the bearing capacity can be increased by increasing the depth of foundation.
• But, this method is not economical because the cost of construction and load on the foundation increase with the
increase in the depth.
(ii) Draining the soil:
• The presence of water in the soil decreases the bearing capacity especially when it is saturated. Hence the water should
be drained from the soil.
• Water can be drained by using gravity pipe drainage system (or) by installing shallow tube wells.
• Drainage results in decrease in the void ratio and improvement of bearing capacity.
(iii) Confining the soil:
• Due to the lateral movement of loose granular soil, the safe bearing capacity of the soil may be low.
• This movement of soil under the action of load can be prevented by confining the ground by the use of sheet piles. The
sheet piles are driven outside the perimeter of foundation area, thus forming an enclosure and confining the soil.
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49
Sheet Piles for soil
confining
Soil Grouting with
cement/chemical

50
Geo-grids for soil
confining
Soil Grouting with
cement/chemical

(iv) Cement Grouting:
• Number of bore holes are driven in the ground.
• Then the cement grout is forced through these holes under a high pressure.
• The voids, cracks and fissures of rocks are filled with the cement grout, thus resulting in the
increase of bearing capacity.
(v) Chemical Grouting:
• This method is as same as cement grout method except which certain chemicals are grouted in
the place of cement grout.
• The chemicals used should be in such a way that it can solidify and gain early strength.
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(vi) Compacting the soil:
Compaction of the soil reduces the open space
between the individual particles and hence it is less
liable to displacement. So the bearing capacity is
increased. Compaction of the soil can be achieved by
the following :
(a) Ramming the moist soil
(b) Rubble compaction
(c) Flooding the soil
(d) Vibrating the soil
(e) Vibrofloatation method
(f) Pre-loading
(g) Sand piles
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Flooring
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“The solid construction that
subdivides the portion between
basement level and roof level is
known as floors and exposed top
surface of floor is known as
floorings.”

Components of Floor
A floor consists of two essential components namely,
(a) Subfloor – Base course or floor base
(b) Floor covering – flooring or paving
(a) Sub floor: A sub floor is a structural component that supports the floor covering. The main
purpose of sub floor is to impart strength for load bearing capacity and stability to support
other super imposed loads.
(a) Floor Covering: The covering over the sub floor is called as floor covering. The main
purpose of floor covering is to provide a hard, clean, smooth and attractive surface to the
floor. Floor covering can also be called as paving or flooring.
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Requirements of Floor
Following are the functional requirements of floors in a building:
(i) Strength and Stability of floors in building:
• Floor strength depends on the properties of material such as timber, reinforce concrete, and steel that are employed to
construct the structure of the floor.
• The strength of floor structure should be adequate to carry dead load of the floor, finishes, fixtures, partitions, services
and expected imposed loads of occupants.
(ii) Resistance of floors to weather and ground moisture:
• There are various factors which affect the moisture penetration level from the ground to the floor includes the nature
of subsoil, water table, and whether the site is horizontal or sloping.
• There is small amount of moisture penetration into the ground if the base is gravel or coarse grain sand (because
water table level is below the surface during the whole year); in this case, concrete slab is suitable solution to resist
moisture penetration.
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Requirements of Floor
(iii) Durability and free from maintenance:
The durability and free from maintenance of floors are rely on the nature of materials applied and the wear they are exposed to.
(iv) Fire Resistance of floors:
• Floors should withstand fire for enough period during which the occupant can get out of the building.
• Reinforced concrete floors combat fire for longer period compare with timber floors.
(v) Resistance to passage of heat:
Ground floor can be constructed in a way that prevents heat transfer from the floor to the ground or from ground to the floor by
applying hardcore and a damp-proof membrane.
(vi) Resistance to passage of sound:
• It is considerably significant that upper floors, which separate dwellings, shall work as barrier and prevent transmission of
sound.
• Reinforced concrete floor work better in preventing transmission of airborne sound compare to low mass timber floor.
• That is why reinforced concrete floor can be effectively used to separate residents.

Selection of Flooring Material
The selection of flooring material i.e. floor covering should be made by considering the following factors:
(i) Initial cost
(ii) Cleanliness
(iii) Appearance
(iv) Durability
(v) Sound insulation
(vi) Fire resistance
(vii) Damp resistance
(viii) Thermal insulation
(ix) Hardness
(x) Smoothness
(xi) Comfort criteria
(xii) Maintenance
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(i) Initial Cost:
• During the selection of a type of floor and floor covering, the cost of construction is one of the important factor.
• The floor coverings like marbles, rubber tiles and special clay tiles are very expensive whereas concrete and brick type
floor coverings are the cheapest type.
(ii) Cleanliness:
• Flooring should be a non-absorbent and should be capable of being cleaned easily. It should be water tight and oil
substance should not affect on flooring material.
• Floorings made up of marble, tiles and slates can be cleaned easily.
(iii) Appearance:
• Floor covering should give pleasing appearance and it should give desired color effect and architectural beauty.
• Flooring of tiles, marbles, cement mortar give pleasing appearances.
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(iv) Durability:
• The flooring material should give long life to floor.
• It should be resistant to temperature, chemical actions, wear and tear, etc.
• Floorings made up of marble, terrazzo, tiles are the best types that gives durability to floor.
(v) Sound Insulation:
• A floor should neither create noise nor transmit noise.
• It is an important factor in case of upper floors, where they act as horizontal barriers for the passage of sound.
• Cork tile flooring and rubber flooring give excellent sound insulation properties.
(vi) Fire Resistance:
• In order to safeguard the life, the flooring material should be resistant to fire.
• This is an important factor in case of upper floor which are required to act as a highly resistant fire barrier.
• Flooring made up of concrete, brick, clay tiles and marble are resistant to fire.
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(vii) Damp Resistance:
• The flooring material should provide sufficient resistance against dampness.
• Flooring made up of clay, tiles, concrete, bricks, terrazzo, etc. are preferred for use where the floors are subjected to
dampness.
(viii) Thermal Insulation:
• The flooring should have good thermal insulation.
• It should maintain constant temperature inside the building.
• Floor covering of wood, rubber, cork, PVC tiles are better for this purpose.
(ix) Hardness:
• The flooring material should be sufficiently hard.
• It should have resistance to marks (or) signs that are caused during shifting (or) rubbing of furniture, equipment etc.
• Flooring made up of concrete, marble, stones, etc. does not show any impressions. 60

(x) Smoothness:
• Flooring should be smooth and even surface but it should not be slippery.
• Floor coverings of tiles, concrete, terrazzo have better performance while considering smoothness.
(xi) Comfort Criteria:
• The flooring should have a shock absorbing and good conductivity property.
• The floorings made up of cork tiles, rubber, wooden blocks, plastic, etc. provide comfort criteria.
(xii) Maintenance:
• The flooring material should require less maintenance.
• It should be such that repairs can be done easily.
• The coverings of tiles, marble, terrazzo, concrete, etc. requires less maintenance.
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Types of Flooring
Based on the materials used, for flooring, the different types of floorings are listed
below:
(i) Mud Flooring
(ii) Stone Flooring
(iii) Brick Flooring
(iv) Timber Flooring
(v) Concrete Flooring
(vi) Mosaic Flooring
(vii) Terrazzo Flooring
(viii) Granolithic Flooring
(ix) Tiled Flooring
(x) Rubber Flooring
(xi) Linoleum Flooring
(xii) Cork Flooring
(xiii) Magnesite Flooring
(xiv) Glass Flooring
(xv) Marble Flooring
(xvi) Plastic (or) P.V.C Flooring
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Concrete Flooring
Concrete flooring is commonly used for residential, commercial and industrial buildings. The
floor has two components namely:
(i) Base Course
(ii) Wearing Course
These two components can be constructed either monolithically (or) non-monolithically.
Monolithic Construction:
• The topping is laid immediately after the base course is laid.
• In this type, base remains in plastic state, so topping get damaged and hairy cracks may
develop.
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Concrete Flooring
Non-Monolithic Construction:
• As the 1st step, the ground should be well-watered, levelled and
rammed.
• Above this, a 15cm hick layer of broken stones is spread and
consolidated. This base is called as the hardcore.
• A layer of lime concrete (1:2:4) about 10cm thick is laid on the
hardcore.
• This layer is watered and well rammed for two days.
• On the third day, the water is drained and a small quantity of dry
cement is sprinkled and it is swept with a broom.
• Then a cement concrete of proportions 1:2:4 about 4cm thickness
is laid. The concrete is rammed and smoothened with a power
float.
• At last finishing surface about 2cm thick cement mortar is laid on
concrete surface
• After flooring is completed, the whole surface is curved with wet
gunny bags.
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Concrete Flooring
Advantages of Concrete Flooring:
(i) It offers resistance to dampness and fire.
(ii) It is smooth, durable, hard, even and gives pleasing appearance.
Disadvantages of Concrete Flooring:
(i) The defects cannot be easily rectified.
(ii) It does not possess satisfactory insulation against heat and sound.
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Terrazzo Flooring
The floor whose topping consists of marble chips (terrazzo) is
known as terrazzo flooring. The construction of terrazzo flooring is
described below:
• The ground surface should be properly rammed and compacted.
• Over this, a 15cm thick sand cushion is laid.
• Over sand cushion a 10cm thick lime concrete is placed
• Above this 3cm thick cement concrete (1:2:4) is laid evenly and
the surface is left without troweling.
• Depending upon the required pattern strips of aluminium, brass
or glass is inserted. The strips should project 25mm above the
level.
• The terrazzo mix containing cement, marble chips and water is
laid over the surface up to the top of dividing surface.
• The surface is levelled by screeding and additional chips may be
added during tamping and rolling operation.
• At last the surface is floated and left to dry for 12 to 20 hours.
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Terrazzo Flooring
Advantages of Terrazzo Flooring:
(i) It provides smooth and even surface.
(ii) It is available in different shades, sizes and colors.
(iii) It has wear-resisting property and decorative effect
Disadvantages of terrazzo Flooring:
(i) Terrazzo flooring coat is very high.
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Marble Flooring
Marble flooring is used in superior type of floor constructions where sanitation and cleanliness are required. Marble
flooring is used in hospitals, temples, theatres, bathrooms, etc.
Marble slabs are available in different sizes and are usually rectangular or square in shape. Its thickness varies from
20mm to 40mm.
The construction of marble flooring is described below:
• A base concrete is prepared in same way as that for concrete flooring.
• Over this, 1:4 cement mortar (bedding for marbles) is spread over it for a thickness of about 20mm under the area of
each slab.
• Then the slab is laid over it, and it is pressed with wooden mallet.
• The laid marble is lifted up again and hollows of bedding mortar are filled by fresh mortar.
• Cement slurry is spread over it and then the edges of the slab are smeared with cement and slurry paste. Then the
slab is again placed in the position.
• The placed marble is pushed with wooden mallet and as a result cement paste oozes out from the joint and it is
cleaned with a cloth.
• The paved area is cured for a week. 68

Marble Flooring
Advantages of Marble Flooring:
(i) It gives aesthetic look.
(ii) Less maintenance is required
Disadvantages of Marble Flooring:
(i) Initial cost is high
69

Roofing
70
“A Roof is the uppermost part of
the building which is supported by
structural members and covered
with roofing materials.
Roof encloses the space or buildings
and protect the building from
various weather agencies”

Requirements of Roof
The selection of roof depends on:
• Availability of materials
• Climate of the place
• Size and shape of the building
• Architectural considerations
• Cost
The requirements of a roof are:
(i) It should be durable against the adverse effects of the natural forces like sun, wind, rain, etc.
(ii) It should be water proof and fire proof
(iii) It should have sufficient thermal insulation capacity
(iv) It should have desirable insulation against sound and heat
(v) It should have adequate strength and stability to withstand the superimposed dead and live load
(vi) It should be well drained.
71

Types of Roof
The roofs are classified according to shape, span and structural design principles as follows:
(i) Flat Roofs
(i) RCC Roof
(ii) Madras Terrace Roof
(ii) Sloping (or) Pitched Roof
(i) Single Roof
(ii) Double Roof
(iii) Trussed Roof
(iii) Curved Roof
(i) Shell Roof
(ii) Dome Roof
72

Flat Roof
• Flat roofs are used in buildings of any shape.
• They are economical too.
• They are suitable for buildings in plains or in hot regions,
where rainfall is moderate and where there is no snowfall.
• Flat roofs are two types: RCC Roof & Madras Terrace
Roof
RCC Roof:
• An RCC roof is commonly and most widely used. In this
roof, concrete with steel reinforcement bars are used to
form a flat roof.
• An RCC roof consists of an RCC slab, built monolithically
with the supporting columns.
• The slab is reinforced in both the principal directions. The
load is carried by the slab, which is directly supported by
the columns.
• The thickness of the roof slab depends on the span and
loading conditions. 73

Flat Roof
74
RCC Roof
on Walls
RCC
Roof
on
Columns

Flat Roof
Madras Terrace Roof:
• This roof is also called as ‘Brick Jelly or Composite Roofs’.
• The construction details of Madras Terrace roof is shown below:
75

Advantages & Disadvantages of Flat Roof
Advantages:
(i) The flat roof can be used for several purposes like a place of celebrating functions, roof garden, drying yards, play
ground, etc.
(ii) Flat roof is stable against high wind
(iii) Flat roof can be made fire proof than a pitched roof.
(iv) Flat roof requires lesser area of roofing material than pitched roof.
(v) Upper floor can be easily constructed.
Disadvantages:
(i) Flat roof cannot be used for long span, without the columns and beams
(ii) Construction speed is slower than the pitched roof
(iii) Flat roof is not suitable for places of heavy snowfall and rainfall
(iv) Initial cost is higher than the pitched roof
76

Pitched Roof (or) Sloping Roof
• Pitched roof consists of decks or surfaces with
considerable slope for covering the building
structure.
• It has pitch exceeding 10 degrees and it is
constructed to drain the rain water easily.
• It is lighter than the flat roof and is constructed
with wood or steel.
• Pitched roof is normally constructed in small
buildings.
• Pitched roof is broadly classified into three:
(i) Single Roof
(ii) Double Roof (or) Purlin Roof
(iii) Trussed roof
77

Single Roof:
In this type of roof, common rafters are provided to each slope without any intermediate support. Following are the types
of single roofs:
(i) Lean to Roof
(ii) Couple Roof
(iii) Couple Close Roof
(iv) Collar beam Roof
78

79

Double or Purlin Roof:
• When the span exceeds about 2.40m, the necessary size for the rafters becomes uneconomical.
• Hence, in order to reduce the size of rafters, intermediate supports, called Purlins are introduced under the rafters.
• Such a roof is called as Double (or) Purlin Roofs.
80

Trussed Roof:
• These are the roofs provided when the span is greater than 4.80m and there are no inside supporting walls or
partitions for the purlins.
• In trussed roof, the rafters support the roof and purlins provide intermediate support to the rafters.
• Different forms of trusses are as follows:
(i) King Post Truss
(ii) Queen Post Truss
(iii) Mansard Truss
(iv) Truncated Truss
(v) Steel Trusses
(vi) Composite Truss
81

82

83
Mansard Truss
Roof
Mansard Truss
Roof

Curved Roof
• Curved Roof is used to cover large area and to
give architectural effect.
• It is the modification of pitched roof.
• These are of two types:
(i) Shell Roof
(ii) Dome
84

Curved Roof
Shell Roof:
• Shell roof is a very thin section of roof structure, resembling the shell of egg.
• There is a lot of saving in material as the section is very thin.
• Shell roof can be constructed with several materials like timber, steel sheets,
ceramics, glass, plastic, RCC, etc. in which RCC shell roof is more popular.
Domes:
• Domes is semi-spherical or semi-elliptical in shape which is used for covering
large circular areas.
• These are used for architectural structure.
• Domes are made up of wood, steel or aluminium.
85

Advantages of Curved Roof
(i) Coverage of huge areas
(ii) Used for industrial structures
(iii) Used in monuments
(iv) Used for big structures like theatres, recreation centers, stadium, libraries, etc.
(v) Thin section is provided and thus savings in material.
87

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