Superstructure

Superstructure is that portion of a building which is constructed above the substructure. It is the major portion of a building which is fully used by human beings. It houses various facilities like number of storeys, floors, roofs, stairs, ventilation, etc. It is the one which provides adequate stability and withstands the adverse weather conditions. Apart from ensuring stability, it adds on to attractive aesthetic appearance. Various components constituting the superstructure are briefly explained below (Fig. 14.1).

1. Basement

Basement or cellar is the lower storage of a building constructed below or partly below the ground surface. It is not used for residential purposes. Basement is used for

1. Storage of household or other goods,
2. As a strongroom for materials, documents and locker for banks,
3. Air-conditioning equipment,
4. Machines used for services and utilities of the building, and
5. Vehicle parking, etc.

2. Plinth

This is the portion of a structure immediately above the ground and between the surface of the floor and the surrounding ground and the road surface so as to provide adequate drainage of the site. The minimum height of the plinth is 45 cm from the surrounding ground level. The top surface of the plinth is the surface over which the ground floor walls are raised and door frames rest.

3. Damp-proof Course

Dampness cause corrosion of materials used in the construction, crumbling and softening of plasters, loosening of floor coverages, blistering of painted surfaces, rotting of wooden parts, etc. Damp-proof materials should be highly impervious.

In order to prevent dampness of wall, a continuous impervious layer is generally provided at the top of plinth level and also in vertical faces of the basement floors.

The materials used for the damp-proof courses are flexible materials like bituminous sheet, plastic sheet, metal sheet, etc.; semi-rigid materials like mastic asphalt; and rigid materials like slates, bricks, stones, dense cement concrete, etc.

4. Wall

It is that part of superstructure which transfers the load of the roof and its self-weight to the foundation through the plinth surface. Materials used for the construction of wall are mud, brick, stone, structural units of clay or concrete. Walls which are responsible to transfer the loads are called load-bearing walls. Partition walls are generally of non-load-bearing and used to partition the space for different purposes. External or outer walls of a building protect the inmates of the building from adverse weathers.

5. Slab

It is a continuous flat portion of a building used as a roof or floor. This is provided to span small opening and distance between beams. It is generally of reinforced cement concrete with reinforcement at the bottom.

6. Beams

It is a horizontal structural member which carries a portion of the wall, floor slab and roof. Beams may be of wood, stone, steel or reinforced cement concrete. Now-a-days reinforced cement concrete beams are used extensively. Reinforced cement concrete beam in its simplest form has a rectangular shape with reinforcement at the bottom and at the top near the supports. In special cases, the beam can be of any shape with reinforcement at the appropriate places.

7. Arch

An arch is a structure comprising of a mechanical arrangement of wedge-shaped blocks. These arches are designed to support the superincumbent load of a wall and provided over doors, windows and passages. The materials used for the construction of arches are bricks, stones and concrete blocks. Steel and reinforced cement concrete are also provided which are built of a single unit and are of rigid type.

8. Lintel

It is a beam that supports the masonry over openings of door, window and passage. Lintels may be wood, stone, steel or reinforced cement concrete. Unlike arches, it does not use a strong supporting wall. Reinforced cement concrete lintels have reinforcements as that in a beam. For small openings, a reinforced brick lintel may be enough.

9. Roof

It is a cover to the inside of a building. Its function is to give a protective covering to the building so that rain, snow or wind may not damage the building. It is constructed at the highest part of the building. Roofs are constructed based on the climatic conditions, material used and type of lighting and ventilation needed. Roofs may be sloping, flat or many have special shapes like shell, folded plates or dome.

10. Floor

It is a level, firm and smooth surface provided at the plinth level in the ground floor for the comfortable use of the inmates of a building. In multi-storeyed buildings, floors divide the building into different levels one above the other for the purpose of providing accommodation within the restricted space. Top floors should also be level, firm, smooth and should be sufficiently strong so as to withstand the loads which come over the floor. It also forms a base surface to take floor coverings. The materials used for floor may be brick, wood, stone, or plain or reinforced cement concrete.

11. Stairs

It is provided in a building to afford a means of communication between floors. These are steps arranged in series and generally placed in the centre or to one side of a building. The stairs should be designed properly so as to provide maximum comfort, ease and safety with adequate ventilation and light. Stairs may be made of timber, brick, stone, mild steel, wrought iron or concrete.

12. Door

It is an opening provided to the outside of a building and for connecting inside rooms of a building. It also gives security and safety. Location of a door should be made so that there is free movement, adequate usable area, privacy and good ventilation. Movements of the door leafs may be swinging, sliding, rolling, revolving, folding or telescopic. Doors may be of wood, aluminium, steel, glass or any combination.

13. Window

It is an opening to the outside to provide adequate natural ventilation and light. While locating a window, the following aspects have to be considered:

1. Distribution and control of day light.
2. Desired vision outside.
3. Privacy.
4. Control of ventilation.
5. Pattern of air movement.

Windows may have one or more shutters. Windows may be of wood, aluminium, steel, glass or any combination.

14. Ventilator

It is provided for ventilation purposes. This can be combined with a door or window frame or provided independently. When provided independently, it is located near the ceiling of the room if the height of the room permits. It may be pivoted or louvered type. Only glass panels or fixed glass louvers are used.

15. Sunshade

It is a horizontal projection provided outside a building at the top of doors and windows to protect the inside of the building from sunlight and rain.

16. Column

It is a structural member intended to support compressive stress. This is provided to support beams both inside and outside a building. Columns may be made of timber, steel, stone, brick or concrete. Columns can be of any shape and provided with some decorative finishes at the top and at the bottom of the columns.

17. Weathering Course

It is a continuous layer provided over the flat roof for protecting the roof from wind, sunlight, rain and snow. The layer may be a combination of concrete with one or more layers of the flat tiles. The thickness of weathering course should be less such that the load on the roof is less, but at the same time should be sound enough to withstand the adverse effects of weather.

18. Parapet

It is a short wall provided on the top of a flat roof of a building to protect people from slipping from top.