To create accommodation within the restricted space, floors divide a building into different levels one above the other. Bottom-most floor of a building of ground level is called a ground floor.
When the bottom-most floor is constructed below the ground level, it is called a basement floor. Floors above ground floor are top or upper floors, viz., first floor, second floor, etc.
Basic requirement of a floor is to be clean, smooth, impervious, durable and strong enough to withstand loads which come over it.
Selection of Floorings
To select a suitable type of floor construction in a building certain factors have to be considered.
Although certain points may be common for ground, upper and basement floors some distinct different points are to be observed in each case.
1. Ground Floors
For ground floors, the selection of the type of the wearing surface is important and the other factors which need consideration are given below:
2. Upper Floors
Selection of a suitable type of construction for upper floors of a building depends on the following main factors:
(iii)Type of construction
(iv)Plan of the building
(v)Function of the building
viii)Type of ceiling
x)Weight and position of floors
3. Basement Floor
Basement floor is not a routine type of floor provided in every building. It is provided for a particular type of buildings like apartments, hotels and restaurants, cinema halls, etc.
Selection of basement floors depends on the following factors:
ii)Availability of ventilation.
iii)Drainage of water from the floor.
iv)Adequate safety against fire.
v)Ground water level.
Construction Practice of Ground Floors
As the ground floor rests directly on the ground, there is no need for a sub-floor. In order to drain the water outside completely adequate drainage arrangements have to be made beneath the floor.
The space above the ground, upto a height of about 25 to 30 cm below the plinth level, called as basement, is filled with some inert materials like sand, gravel, crushed stone, cinder, etc.
Over this course a damp-proof-course if needed is laid. Otherwise the floor covering is laid directly on the uniform bed.
Materials used for ground floor construction are : bricks, stones, concrete, hollow concrete blocks or wooden blocks. Materials generally used for floor coverings are : bricks, concrete, terrazzo, tiles, marbles, stones, mosaic, wood, etc.
1. Stone Flooring
Usual sizes of stones of 30 cm × 30 cm, 45 cm × 45 cm or 60 cm × 60 cm with a thickness of 2 to 4 cm are used. Square stone slabs of the above sizes are used but the slabs can be of rectangular or oblong in shape with square edges.
Stone slabs are laid on concrete bedding. Before laying the slab, a base is prepared after excavating to the required depth and the earthen base is levelled, rammed and watered.
A layer of lime concrete of thickness 10 to 15 cm is spread over which the concrete bed or subgrade is laid.
After setting the stone floor with a slope of 1 in 40, the mortar joints are raked out to a depth of 2 cm and flush pointed with cement mortar of 1 : 3.
2. Brick Flooring
It is used in case of warehouses, stores and godowns. Is a cheap construction, also used in areas when stones are not available but good quality bricks are available.
It may be laid flat or on edge and arranged in herring bone pattern or at right angles to the walls.
Brick on edge is preferred compared to bricks laid flat as the brick-on-edge is less liable for crack under pressure because of the higher depth.
Bricks, in both the cases, are laid on ordinary mortar and pointed with cement or set in hydraulic mortar.
The construction of brick flooring is done as given below Fig.
1.An excavation of about 40 cm depth below the intended level of the floor is made.
2.The earth surface is levelled, watered and well rammed until it is dry and hard.
3.Over the earth above a sub grade of 25 cm depth consisting of rubble or brick bats is laid.
4.Over this a 10 to 15 cm thick layer of lime concrete or lean cement concrete (1 : 3 : 6) is laid.
5.Upon this prepared subgrade, bricks are laid in the desired shape.
3. Concrete Flooring
It is used in all residential, commercial and public buildings. Constructed adopting either monolithic or non-monolithic construction.
In the monolithic construction, after laying the base course layer, immediately a concrete topping is provided.
In this type of construction, only a small thickness is needed for wearing surface as the bond between the base course and the wearing surface is good.
In Non-monolithic construction, the wearing surface is laid only after adequate drying of base course. Floor finish generally used is ordinary concrete finish.
Proportion of concrete finish is 1 : 1½ : 3. Under controlled conditions, a mix of 1 : 2 : 4 ratio with carefully selected aggregates may be used Fig.
For non-monolithic construction, the surface of the base concrete is brushed with a stiff broom and cleaned thoroughly. Surface is wetted and excess water removed.
Floor is laid in rectangular panels not greater than 2 m × 2 m. Alternate bays are concreted so as to avoid initial shrinkages.
When the concrete layer is even, the surface is rapidly compacted by ramming or beating and screened to a uniform level. Trowelling is done to give a level smooth surface.
Adequate curing is done for 7 days by spreading a layer of wet sand or special membrane may be used.
4. Granolithic Flooring
It is a concrete flooring with a different type of floor finish called granolithic. Granolithic finish is a concrete made of special selected aggregate.
Thickness of layer varies from 1.25 to 4 cm. If it is greater than 4 cm it may be laid monolithically or after the base concrete has hardened. It is made with very hard and tough quality aggregate in rich concrete of 1 : 1 : 2.
Hard fine grained granite, basalt, lime-stone and quartz stones are suitable for coarse aggregate. To get a better granolithic finish, aggregate may be crushed and used.
Fine aggregates are the natural or crushed sands with a suitable grading. Non-slippery surfaces can be obtained by adding suitable abrasives.
In case of non-monolithic construction, the base course may be prepared as done in concrete flooring. Granolithic flooring has all the advantages of concrete flooring.
5. Terrazzo Flooring
It is a special type of concrete flooring containing marble chips as aggregates. Any desired colour and designs can be obtained by using marble chips of different shades and colour cement.
Terrazzo mix of 1 : 2 or 1:3 (1 cement to 2 to 3 marble chips) is used depending on the size of marble chips. Terrazzo finish is of 10 mm thick.
The terrazzo finish is laid over the concrete base course by two methods.
1.The cement concrete base is covered uniformly by a 6 mm thick sand cushion and a tar paper is placed on this. Over this a layer of rich mortar (1:3) about 30 mm is placed uniformly.
2.A thin coat of cement is spread over the wet concrete base. This layer is cleaned and a layer of cement mortar 12 mm thick is spread evenly over it.
When the mortar bed has hardened the terrazzo mix (1 cement: 3 marble chips) of 6 mm and 12 mm is laid after adding water and making workable mix.
After curing for several days, the surface is polished by means of grinding machine fitted with carborundum grinding stone disc.
During grinding, the surface is kept wet and small holes or pores are filled with a suitable cement paste matching the surface configuration.
Surface is then washed with a weak solution of soft soap in warm water. This type is used in public buildings like banks, hotels, offices, etc., because of its decorative appearance and excellent wear-resisting properties.
6. Mosaic Flooring
In this flooring, a hard concrete base is laid first. When the base is wet a 2 cm layer of cement mortar (1 : 2) is evenly laid.
Over this layer, small pieces of broken tiles are arranged in different pattern. The inner space between tiles is filled with coloured pieces of marble in the desired fashion.
Following this, cement or coloured cement is sprinkled at the top to get a complete floor without pores. Surface is then rolled by light stone roller till an even surface is obtained.
After 24 hours of drying the surface is rubbed with a pumice stone 20 cm × 20 cm × 7 cm fitted to a long wooden handle. Polished surface is allowed to dry for two weeks before put into use.
7. Tiled Flooring
Here tiles either of clay or cement concrete, manufactured in different shapes, are used. A 15 cm thick layer of lime or cement concrete is laid over the levelled ground.
In order to receive the tiles at 25 mm thick layer of lime mortar (1:3) or cement mortar (1:1) is laid. A cement slurry is spread over the hardened mortar.
Tiles are laid flat on this bed and a cement paste is applied on the sides. Joints are rubbed with carborundum stone after allowing 2 to 3 days for setting.
Entire surface is polished with a pumice stone Fig.
Tiled floorings are used in residential buildings, hotels, offices and other public buildings. These floors can be constructed in very short time with pleasing appearance and good durability.
Special Types of Ground Floor
1. Asphalt Flooring
Asphalt floorings are of two types, viz.,
(i) Using asphalt tiles.
(ii) Using mastic asphalt.
Asphalt tiles are made from asphalt, asbestos fibres and materials under pressure.
Asphalt mastic is a mixture of fine aggregates and natural or artificial asphalt.
Asphalt tiles are used to cover wooden or concrete floors. These tiles are resilient, non-absorbent, moisture proof and cheap. It is used in schools, offices and hospitals, etc.
Asphalt mastic can be mixed hot and laid in continuous sheets or pressed into blocks which can be used for flooring.
It may also be mixed with oil and asbestos and applied cold. An ordinary concrete or wood base may be used for laying this mixture.
2. Linoleum Flooring
Linoleum is a covering material generally laid over wooden or concrete floors.
Linoleum material is lubricated by mixing oxidised linseed oil with gum, resin, pigments, wood floor, cork dust and other filler materials. Available as rolls of 2 or 4 m width with 2 to 2.5 mm thick and both in plain and printed forms.
Linoleum covering are fixed to the sub-floor by means of suitable adhesive in order to have adequate bond and high durability. It is used in residential and public buildings.
3. Cork Flooring
Natural cork is the outer bark of the cork oak tree manufactured in the form of tiles and rolls like linoleum.
Cork tiles are made from high grade cork bar and are manufactured in the sizes of 10 cm x 10 cm to 30 cm x 90 cm and of 5 to 15 mm thickness. Cork tiles are available with light and heavy density.
Cork tiles are provided with joints of tongue and groove type or butt type. Rolls or carpets of cork are made by heating granules of cork with linseed oil and then compressing it by rolling on canvas. Maintenance of cork carpet is difficult.
Laying of cork flooring is similar to that linoleum covering. Cork flooring provides a warm, noiseless non-slippery, resilient flooring and with good heat insulation qualities. Preferred in libraries, churches, hospitals, broad casting studios, theaters,etc.
4. Glass Flooring
Here Structural glass in the form of tiles or blocks are used. Fitted within the frames of various types. Structural glass are available in different forms of varying thicknesses usually from 10 to 30 mm.
Frame work holding the structural blocks should be closely spaced so as to take the anticipated loads and to be safe. Used for special purposes, e.g., to transmit light from one floor to another or for a dancing hall or for a decorative purpose.
5. Plastic or EVC Flooring
Manufactured in the form of tiles. Available in various sizes, and colours and shades. Laid in the similar way as cement or clay tiles. It is slippery and hence cannot be used for a normal flooring.
6. Marble Flooring
Construction procedure is same as that of mosaic flooring except that marble slabs or pieces are used instead of mosaic tiles or pieces.
Preferred when sanitation and cleanliness are required as in the case of hospitals, temples, theaters and other superior type of works.
7. Timber Flooring
This type is not preferred for ground floors. If it is used as a ground floor, the prevention of dampness is most important. For fixing the timber floors on concrete slabs, longitudinal nailing strips are provided.
Planked flooring should be laid with spaces of metals spaced 1 mm apart temporarily for providing expansion joints. Strip flooring is used in thicknesses of 2 to 2.5 cm and width of 6 to 10 cm.
Wooden flooring details
Construction of Upper Floors
Upper floors should be strong to take heavy loads, should have sound insulation and fire resistance and also have a good wearing resistance.
Upper floors are generally classified based on the materials of construction, arrangement of beams and girders or materials used.Commonly used upper floors are explained below.
1. RCC Slab Floor
All modern buildings are invariably constructed with reinforced cement concrete. For small spans a simple RCC slab floor is generally suitable.
For rooms, with the ratio of length of room to its width is greater than 1.5, slabs are designed to span along the shorter width. Main reinforcements are placed to the shorter width.
Thickness of the slab depends on the type of concrete used, the span, floor loads, etc. Reinforced concrete slabs are laid adopting the routine mixing, laying, finishing and curing.
Slab provides a very smooth surface at the bottom and a pleasing appearance. Accommodates all lighting arrangements.
The RCC slabs are restricted up to 4 m span beyond which beam and slab construction has to be adopted.
2. RCC Beam and Slab Floor
It is used for larger spans and heavy loading conditions. Commonly used for most of the important buildings.
Beams and slabs are designed as rectangular sections and the slabs are supported on beams. Beam used in monolithic construction is called a T-beam, i.e., a part of slab acts as a flange of the T-beam.
Main reinforcement of the slab runs parallel to the short span. In case of equal spans, two-way slabs may be constructed with reinforcement provided on both directions.
Projecting beams are covered by providing a false ceiling underneath it.
The construction procedure is same as that of RCC slab floor, except for the type of centering or formwork required for the floor.
3. Flat Slab Floor
It is also called as beam less slab floor. It is directly supported on columns without any intermediate beams. Preferred where heavy loads are anticipated and where there is head room restriction.
Columns supporting the floor are invariably circular in cross-section and tops of the column are flared or tapered, which is called as capital.
Certain portion of the slab, symmetrical with the column, is thickened which is called drop panel.
...(download the rest of the essay above)