9 COMPONENTS OF A BUILDING

S. Premalatha

epgp books

 

 

 

 

1.    Introduction

 

In general, a building is made of several components such as

 

  •   Foundation
  •   Basement
  •    Plinth and plinth level
  •    Walls and piers in superstructure
  •    Doors and windows
  •    Sills
  •    Lintel beam
  •    Roofs
  •    Steps and stairs
  •    Finishes for walls
  •   Utility fixtures

Each of these components is an essential part of a building and requires due consideration in design and construction for their functional performance..

  1. Learning Objectives

At the end of the course the students will be able to

  • Identity the components of a building
  • Know the basic requirements of each building component
  1. Building components and its Basic requirements A building basically consists of three parts, namely

 

i) Foundation

ii) Plinth

iii) Superstructure

 

3.1 Foundation or Substructure

 

The portion of the building below the ground level which is in direct contact with the ground to transmit the loads of the building to the ground is called as foundation or substructure.

 

The foundation is the most critical part of any structure and most of the failures are probably due to faulty foundations rather than any other cause. Hence, it is highly essential to secure good foundations to maintain the stability of the structure. The primary function of the foundation is to transmit the anticipated loads safely to the soil below.

 

In a small building, footing foundations or strip footing foundations with two or three footings of brick masonry or stone masonry are used, over a concrete bed.

 

3.2 Plinth and Plinth Level

 

This is the portion of structure between the surface of the surrounding ground and surface of the floor, immediately above the ground . The portion of the building between the ground and floor level in the super structure is called as plinth.

 

Its height above the ground level is known as plinth level or plinth height. The thickness of the plinth wall depends upon the weight of the super-structure and the width of foundation concrete. The plinth height depends upon various factors such as need of architectural treatment to a building, highest flood level of area, adjoining ground nature.

 

Its height is usually 450 mm, 600 mm or 750 mm from ground level and it depends upon the site condition. The thickness of the wall in plinth may be bigger than the wall thickness. In a small building the plinth wall thickness is about 230 to 300 mm. The space between ground and plinth level in a building is filled with sand.

 

The plinth wall is constructed

  • to transmit the load of the superstructure to the foundation
  • to act as a retaining wall so as to keep the filling in position below the floor of the building
  • To protect the building from moisture penetration into it. This increases the stability and durability of the structure
  • It enhances the architectural appearance of the building

3.2.1 Plinth beam

 

The Reinforced cement concrete beam shortly named as RCC beam constructed in the plinth which is used to transfer the load of building uniformly, on the foundation is called as plinth beam. It also prevents any crack formation on the wall because of the improper settlement and behavior of the soil on which the building is constructed. Its thickness is usually 150 mm and the width is equal to the wall thickness 300 mm in the plinth.

 

3.2.2 Basement

 

Basement is the lower storey of a building which is partly or fully below the ground level. In an office building or a residential building, basement is used for vehicle parking or for storage of goods.

 

3.2.3 Damp-proof course

 

The building should be dry for the longer life of it and in order to prevent the entry of dampness into the building, the damp proof course is provided.

 

The main entry of dampness in a building is through the foundation which absorbs moisture by capillary action. It is prevented by providing a cement mortar, impervious layer in the ratio 1:3, mixed with water proofing materials for thickness of 20mm at the plinth level.

 

3.3 Superstructure

 

The portion of the building above the ground level or substructure is called Superstructure. The components of a super structure are plinth, wall, lintel, roof etc.

 

3.3.1 Wall

 

The portion of the super structure which carries the load of the roof is called as the wall. The primary function of wall is to enclose or divide the space. A load-bearing wall in the super-structure should be strong enough to take up the loads safely due to its own weight, super imposed loads and lateral pressure such as wind. It should be stable against overturning by lateral forces and buckling caused by excessive slenderness. The wall is built in brick masonry and commonly has a thickness of about 230 mm.

 

All the external walls, whether of load bearing construction, should provide adequate resistance to rain, sun and wind penetration. The walls should offer sufficient resistance to fire, as they behave as vertical barriers for spread of fire in the horizontal direction. It should be possible for walls to attain insulation against heat using heat insulating materials. The walls, particularly external walls, should also provide sufficient privacy and afford security against burglary.

 

3.3.2 Partition wall

 

Partition walls are used to make separation or division in a room, and they have a thickness of 100 milli meter. These are not load bearing walls and they don’t have any foundation like walls in a building. Partitions can also be obtained by using timber and glass, this type is commonly used in office buildings.

 

3.3.3 Parapet wall

 

The wall built above the flat roof, which provides safety to the people, while they are on the top of the roof in a building, is called as a parapet wall. Also this adds good appearance to a building. The parapet wall thickness may be from 115 mm or 230 mm. Its height is usually 600 mm to 900 mm.

 

3.3.4 Flooring

 

The horizontal surface at the plinth level in a building is called as flooring. The main function of a floor is a to provide support for occupants, furniture and equipment of a building and the function of providing different floors is to divide the building into different levels for the purpose of creating more accommodation within the limited space.

   All the floors, whether basement, ground or upper, should be strong enough to support the floor covering and other superimposed loads. The flooring or floor covering of all the floors should provide a clean, smooth, impervious, durable and weather resisting surface. The insulation against heat and sound should be provided.

 

It is usually prepared in two layers. The first layer is plain cement concrete shortly named as PCC in the ratio of 1:4:8 (that is 1 part of cement, 4 parts of sand and 8 parts of coarse aggregate or simply jelly) is constructed for a thickness of about 120 mm. The second layer is the finishing layer which may be cement plastering in the ratio of 1:3 ( that is one part of cement and 3 parts of sand makes cement mortar ) for a thickness of 20 mm. This can be mosaic tiles, marble slabs, superior quality granite slabs, or ceramic tiles flooring.

 

3.3.5 Sills

 

The horizontal bottom level of a window is called as sill level. In building drawing, the top view or plan is drawn by considering a section plane at this level. Window sills are provided between the bottom of window frame and wall below to protect the top of wall from wear and tear. Window sills are usually weathered and throated to throw the rain water off the face of the wall.

 

3.3.6 Roofs

 

A roof is the uppermost part of a building whose main function is to enclose the space and protect the same from the effects of weather elements such as rain, sun, wind, heat, snow etc.

 

The reinforced cement concrete shortly named as RCC slab used to cover the building is called as roofing. It is constructed as flat or inclined RCC slab of thickness 120 mm and the mix ratio is 1:1.5:3 (that is 1 part of cement, 1.5 parts of sand and 3 parts of jelly). There are much other type of roofs, but RCC roof is commonly used in small offices and residential buildings.

 

3.3.7 Ceiling

 

The bottom surface of roof slab, seen inside a room is called as ceiling. The normal height of ceiling for residential buildings measured from floor in a room, to have the facilities of a ceiling fan etc. is 3000 mm. This height may be reduced for the buildings that are to be air-conditioned.

 

3.3.8 Lintel Beam

 

The actual frame of a door or window is not strong enough to support the weight of the wall above the opening. Hence a Reinforced cement concrete beam constructed above the window and door openings to support the brick work above is called as lintel beam. Its thickness is usually 150 mm and the width is equal to the wall thickness of 230 mm. The height of lintel beam level is equal to the door height which is usually 2100 mm from floor level.

 

3.3.9 Weathering Course

 

In order to prevent the entry of rain water into the RCC roof slab and transfer of heat inside the room, below the roof during summer, the weathering course is provided.

 

The simple method on weathering course is using lime concrete. Lime mixed with broken brick aggregate of size 25mm to 35mm in the ratio 1:2.5 for an average thickness of 90mm. While laying the weathering, a slope of 1: 50 towards rain water drainage pipe is provided. A course of flat tiles with cement mortar in the ratio 1:3 mixed with crude oil is provided on top of the lime concrete, to have a good weathering course.

 

3.3.10 Sunshade

 

Sunshade is a horizontal reinforced cement concrete slab provided above the windows and doors to prevent sunlight and rain water entry into the rooms. It is constructed by providing an extension from lintel beam. Its joining thickness at lintel is 75mm and the bottom surface of sunshade is flat and the slope is obtained in the top surface.

 

The width of the sunshade is 450 mm to 600 mm and is extending by 150 mm on either side of door and window.

 

3.3.11 Steps

 

Steps are built to enable us to reach a floor and are generally constructed in brickwork, on a plain cement concrete bed of thickness 100 mm to 200 mm.

 

The height of a step is called as rise which usually 150 mm and the width of a step is called as tread which is usually 250 to 300 mm. The length of a step is slightly larger than the door size by extending 100 mm to 150 mm on either side of door. If the tread size is reduced or riser thickness is increased than the above mentioned value, it makes the users inconvenient and hence provision of above mentioned size is necessary.

 

3.3.12 Stairs

 

A stair is a structure consisting of number of steps leading from one floor to another floor. Location of stair in all types of residential and public building should be such as to afford the easiest and quickest service possible to the building. It may be constructed outside or inside of a building.

 

The main function of stairs is two-fold. Firstly to provide means of communication between the various flows for everyday use and secondly that of escape from upper floor in the event of fire.

 

Dwelling houses should desirably have two stairs – the front or principal stairs for everyday use and a back stair for the service of the house and also to serve as an escape way in case of emergency. It is advisable to always place a staircase against a wall as it affords ease of construction, lighten ventilation, economy of space and safety in movement.

 

Commonly used stairs are

  • Straight flight stairs
  • Dog legged stairs
  • Circular stairs
  • Spiral stairs

3.3.13 Doors and Windows

 

The main function of doors in a building is to serve as a connecting link between internal parts and also to allow the free movement into and outside the building.

 

Windows are generally provided for the proper ventilation and lighting of a building, and their size and numbers should be properly determined as per requirements.

 

They should be strong enough to resist the adverse effects of weather such as wind, rainfall etc. , capable of being made air-tight to achieve insulation against sound and heat. They should not be affected by white ants and moisture penetration.

 

3.3.14 Finishes for walls

 

Finishes for walls of several types such as pointing , plastering, painting, distempering, decorative color washing etc are applied on the walls. They protect the structure particularly the exposed surfaces from the effects of weather such as rain, sun, snow, etc.

 

They provide a true even and smooth finished surface and also improve the aesthetic appearance of the structure as a whole. They also rectify rather cover to some extent the poor or defective workmanship.

 

3.3.15 Utility Fixtures

 

These are built in items of an immovable nature which add considerably to the utility of the building and hence termed as utility fixtures. The most common of such built in fixtures are cupboards, shelves etc. these features are generally provided in the recesses for storing valuable articles etc. The recesses in wall structure reduce its strength so they are avoided in the modern construction of houses.

 

Thus by abiding the correct proportion of every building material that is to be used in the process of constructing a house/residential building, it adds more safety and longer usability of the building.

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