ELEMENTS OF A BUILDING
The following are the basic elements of a building:
1. Foundation
2. Plinth
3. Walls and columns
4. Sills, lintels and chejjas
5. Doors and windows
6. Floors
7. Roofs
8. Steps, stairs and lifts
9. Finishing work
10. Building services.
The functions of these elements and the main requirement of them is presented in this article.
1. Foundation: Foundation is the most important part of the building. Building activity starts with digging the ground for foundation and then building it. It is the lowermost part of the building. It transfers the load of the building to the ground. Its main functions and requirements are:
(a) Distribute the load from the structure to soil evenly and safely.
(b) To anchor the building to the ground so that under lateral loads building will not move.
(c) It prevents the building from overturning due to lateral forces.
(d) It gives level surface for the construction of superstructure.
2. Plinth: The portion of the wall between the ground level and the ground floor level is called
plinth. It is usually of stone masonry. If the foundation is on piles, a plinth beam is cast to support wall above floor level. At the top of plinth a damp proof course is provided. It is usually 75 mm thick plain concrete course.
The function of the plinth is to keep the ground floor above ground level, free of dampness. Its height is not less than 450 mm. It is required that plinth level is at least 150 mm above the road level, so that connections to underground drainage system can be made.
3. Walls and Columns: The function of walls and columns is to transfer the load of the structure vertically downwards to transfer it to foundation. Apart from this wall performs the following functions also:
(a) It encloses building area into different compartments and provides privacy.
(b) It provides safety from burglary and insects.
(c) It keeps the building warm in winter and cool in summer.
4. Sills, Lintels and Chejjas: A window frame should not be directly placed over masonry. It is placed over 50 mm to 75 mm thick plain concrete course provided over the masonry. This course is called as sill. Lintels are the R.C.C. or stone beams provided over the door and window openings to transfer the load transversely so as to see that door or window frame is not stressed unduly. The width of lintels is equal to the width of wall while thickness to be provided depends upon the opening size. Chejja is the projection given outside the wall to protect doors and windows from the rain.
They are usually made with R.C.C. In low cost houses stone slabs are provided as chejjas. The projection of chejja varies from 600 mm to 800 mm. Sometimes drops are also provided to chejjas to improve acsethetic look and also to get additional protection from sun and rain.
5. Doors and Windows: The function of a door is to give access to different rooms in the building and to deny the access whenever necessary. Number of doors should be minimum possible. The size of the door should be of such dimension as will facilitate the movement of the largest object likely to use the door.
Windows are provided to get light and ventilation in the building. They are located at a height of 0.75 m to 0.9 m from the floor level. In hot and humid regions, the window area should be 15 to 20 per cent of the floor area. Another thumb rule used to determine the size and the number of windows is for every 30 m3 of inside volume there should be 1 m2 window opening.
6. Floors: Floors are the important component of a building. They give working/useful area for the occupants. The ground floor is prepared by filling brick bats, waste stones, gravel and well compacted with not less than 100 mm sand layer on its top. A lean concrete of 1 : 4 : 8, 100 mm thick is laid. On this a damp proof course may be provided. Then floor finishing is done as per the requirement of the owner. Cheapest floor finish for a moderate house is with 20 to 25 mm rich mortar course finished with red oxide. The costliest floor finish is mossaic or marble finishing. Other floors are usually of R.C.C. finished as per the requirements of the owner.

7. Roof: Roof is the top most portion of the building which provide top cover to the building. It should be leak proof.Sloping roof like tiled and A.C. sheet give leak proof cover easily. But they do not give provision for the construction of additional floor. Tiled roof give good thermal protection. Flat roofs give provision for additional floors. Terrace adds to the comfort of occupants. Water tanks can be easily placed over the flat roofs.
8. Step, Stairs and Lifts: Steps give convenient access from ground level to ground floor level.They are required at doors in the outer wall. 250 to 300 mm wide and 150 mm rise is ideal size for steps. In no case the size of two consecutive steps be different. Number of steps required depends upon the difference in the levels of the ground and the floor.
Stairs give access from floor to floor. They should consists of steps of uniform sizes. In all public buildings lifts are to be provided for the conveniences of old and disabled persons.In hostels G + 3 floors can be built without lifts, but in residential flats maximum floors permitted without lifts is only G + 2. Lift is to be located near the entrance. Size of the lift is decided by the number of users in peak hours. Lifts are available with capacity 4 to 20 persons.
9. Finishing: Bottom portion of slab (ceiling), walls and top of floor need smooth finishing with plaster. Then they are provided with white wash, distemper or paints or tiles. The function of finishing work is:
(a) Give protective cover
(b) Improve aesthetic view
(c) Rectify defective workmanship
(d) Finishing work for plinth consists in pointing while for floor it consists in polishing.
10. Building Services: Water supply, sanitation and drainage works, electric supply work and construction of cupboards and show cases constitute major building services. For storing water from municipal supply or from tanker a sump is built in the house property near street. From the sump water is pumped to over head tanks placed on or above roof level so as to get water all the 24 hours. Plumbing work is made so as to get water in kitchen, bathrooms, water closets,
sinks and garden taps. For draining rainwater from roofs, down take pipes of at least 100 mm diameters should be used. Proper slopes should be given to roof towards down take pipe. These pipes should be fixed at 10 to 15 mm below the roof surface so that rainwater is directed to the down take pipe easily. The sanitary fittings are to be connected to stone ware pipes with suitable traps and chambers.
Stone ware pipes are then connected to underground drainage of municipal lines or to the septic tank.Many carpentry works are required for building service. They are in the form of showcases,cupboards, racks etc.Electric supply is essential part of building services. The building should be provided with sufficient points for supply of lights, fans and other electric gadgets.

Roof is the uppermost portion of the building which protects the building from rain, wind and sun. Various types of roofs used may be divided broadly into three types:
1. Flat roofs
2. Pitched roofs
3. Shells and folded plates.

Flat roofs are used in plains where rainfall is less and climate is moderate. Pitched roofs are preferred wherever rainfall is more. Shells and folded plate roofs are used to cover large column free areas required for auditoriums, factories etc.
 Brief description of these roofs is presented below:
1. Flat Roofs: These roofs are nearly flat. However slight slope (not more than 10°) is given to drain out the rain water. All types of upper storey floors can serve as flat roofs. Many times top of these roofs are treated with water proofing materials-like mixing water proofing chemicals in concrete, providing coba concrete. With advent of reliable waterproofing techniques such roofs are constructed even in areas with heavy rain fall.
The advantages of flat roofs are:
(a) The roof can be used as a terrace for playing and celebrating functions.
(b) At any latter stage the roof can be converted as a floor by adding another storey.
(c) They can suit to any shape of the building.
(d) Over-head water tanks and other services can be located easily.
(e) They can be made fire proof easily compared to pitched roof.
The disadvantages of flat roofs are:
(a) They cannot cover large column free areas.
(b) Leakage problem may occur at latter date also due to development of cracks. Once leakage problem starts, it needs costly treatments.
(c) The dead weight of flat roofs is more.
(d) In places of snow fall flat roofs are to be avoided to reduce snow load.
(e) The initial cost of construction is more.
(f) Speed of construction of flat roofs is less.
Types of Flat Roofs:
All the types listed for upper floors can be used as flat roofs.
 Pitched Roofs: In the areas of heavy rain falls and snow fall sloping roof are used. The slope of roof shall be more than 10°. They may have slopes as much as 45° to 60° also. The sloped roofs are known as pitched roofs. The sloping roofs are preferred in large spanned structures like workshops, factory buildings and ware houses. In all these roofs covering sheets like A.C. sheet, G.I. sheets, tiles, slates etc. are supported on suitable structures. The pitched roofs are classified into
(a) Single roofs
(b) Double or purlin roofs
(c) Trussed roofs.
(a) Single Roof:
If the span of roof is less than 5 m the following types of single roofs areused.
(i) Lean to roofs
(ii) Coupled roofs
(iii) Coupled-close roof
(iv) Collar beam roof
In all these roofs rafters placed at 600 mm to 800 mm spacing are main members
taking load of the roof. Battens run over the rafters to support tiles.
(b) Double or Purlin Roofs:
If span exceeds, the cost of rafters increase and single roofbecomes uneconomical. For spans more than 5 m double purlin roofs are preferred. The intermediate support is given to rafters by purlins supported over collar beams
(c) Trussed Roof:
 If span is more, a frame work of slender members are used to support sloping roofs. These frames are known as trusses. A number of trusses may be placed lengthwise to get wall free longer halls. Purlins are provided over the trusses which in turn support roof sheets. For spans up to 9 m wooden trusses may be used but for larger

spans steel trusses are a must. In case of wooden trusses suitable carpentry joints are
made to connect various members at a joint. Bolts and straps are also used. In case of
steel trusses joints are made using gusset plates and by providing bolts or rivets or welding.Depending upon the span, trusses of different shapes are used. End of trusses are supported on walls or on column.

3. Shells and Folded Plate Roofs: Shell roof may be defined as a curved surface, the thickness of which is small compared to the other dimensions. In these roofs lot of load is transferred by membrane compression instead of by bending as in the case of conventional slab andbeam constructions. Caves are having natural shell roofs. An examination of places of worships built in India, Europe and Islamic nations show that shell structures were in usage for the last 800 to 1000 years. However the shells of middle ages were massive masonry structures but nowadays thin R.C.C. shell roofs are built to cover large column free areas.

Advantages and Disadvantages of Shell Roofs
Advantages of shell roofs are:
(a) Good from aesthetic point of view
(b) Material consumption is quite less
(c) Form work can be removed early
(d) Large column free areas can be covered.
Disadvantages are:
(a) Top surface is curved and hence advantage of terrace is lost.
(b) Form work is costly.
Folded plate roofs may be looked as slab with a number of folds. These roofs are also known as hipped plates, prismatic shells and faltwerke. In these structures also bending is reduced and lot of load gets transferred as membrane compression. However folded plates are not so efficient as shells.


Advantages and Disadvantages of Folded Plate Roofs over Shell Roofs
Advantages are:
(a) Form work required is relatively simpler.
(b) Movable form work can be employed.
(c) Design involves simpler calculations.
Disadvantages are:
(a) Folded plate consume more material than shells.
(b) Form work can be removed after 7 days while in case of shells it can be little earlier. Roof Coverings for Pitched Roofs
Various types of covering materials are available for pitched roofs and their selection depends upon the climatic conditions, fabrication facility, availability of materials and affordability of the owner. Commonly used pitched roof covering materials are:
(a) Thatch
(b) Shingle
(c) Tiles
(d) Slates
(e) Asbestos cement (A.C.) sheets ( f ) Galvanised iron (G.I.) sheets
(a) Thatch Covering: These coverings are provided for small spans, mainly for residentia buildings in villages. Thatch is a roof covering of straw, reeds or similar materials. The thatch is well-soaked in water or fire resisting solution and packed bundles are laid with their butt ends pointing towards eves. Thickness varies from 150 mm to 300 mm. They are tied with ropes or twines to supporting structures. The supporting structure consists of round bamboo rafters spaced at 200 mm to 300 mm over which split bamboos laid at right angles at close spacing. It is claimed that reed thatch can last 50 to 60 years while straw thatch may last for 20–25 years.

The advantage of thatch roof is they are cheap and do not need skilled workers to build them.The disadvantages are they are very poor fire resistant and harbour rats and other insects.
(b) Shingles: Wood shingles are nothing but the split or sawn thin pieces of wood. Their size varies from 300 mm to 400 mm and length from 60 mm to 250 mm. Their thickness varies from 10 mm at one end to 3 mm at the other end. They are nailed to supporting structures. They are commonly used in hilly areas for low cost housing. They have very poor fire and termite resistance.
(c) Tiles: Various clay tiles are manufactured in different localities. They serve as good covering materials. Tiles are supported over battens which are in turn supported by rafters/trusses etc.Allahabad tiles, Mangalore tiles are excellent inter-locking tiles. They give good appearance also.
(d) Slates: A slate is a sedimentary rock. Its colour is gray. It can be easily split into thin sheets. Slates of size 450 mm to 600 mm wide, 300 mm long and 4 to 8 mm thick are used as covering materials of pitched roofs in the areas where slate quarries are nearby. A good slate is hard, tough, durable. They are having rough texture and they give ringing bell like sound when struck. They do not absorb water.

(e) A.C. Sheets: Asbestos cement is a material which consists of 15 per cent of asbestos fibres evenly distributed and pressed with cement. They are manufactured in sufficiently large size. The width of a A.C. sheet varies from 1.0 to 1.2 m and length from 1.75 to 3.0 m. To get sufficient strength with thin sections they are manufactured with corrugation or with trafford's They are fixed to the steel purlins using J-bolts. The roofing is quite economical,waterproof.
 However not very good thermal resistant. They are commonly used as covering materials in warehouses, godowns or for larger halls. In auditorium etc., if these sheets are used, false ceilings are provided to get good thermal resistance.( f ) G.I. Sheets: Galvanised iron corrugated sheets are manufactured in the sizes 1.0 to 1.2 m wide and 1.65 m length. Galvanisation of iron makes them rust proof. They are fixed to steel purlins using J-bolts and washers. They are durable, fire proof, light in weight and need no maintenance. They are commonly used as covering materials for warehouses, godown, sheds Etc.