Ancient Egyptians were the first to make tiles using clay baked in kilns. The Mesopotamians introduced terracotta and ceramic tiles. The Chinese developed porcelain tiles.
The most commonly used tiles in residential construction today are manufactured using ceramic. Although cork, concrete, metal, glass and composite materials are also used in making tiles. They were made to replace coloured bricks, and are used as covering material on floors, ceilings and roofs, the main purpose being decoration. Tiles are usually thin rectangular (or square) pieces of ceramic.
Ceramic and porcelain tiles are economical and require less maintenance than natural stone tiles (like marble, slate and granite). Both ceramic and porcelain tiles are best suited for flooring. Ceramic tiles can be used in bathrooms and kitchens because of their waterproof nature.
In contrast, Natural stones can be used in spaces where they are exposed to high amounts of moisture, provided their porous surface is sealed using appropriate sealants.
Classification of Tiles:
Tiles can be classified based on various parameters. Some of them are:
- Based on Usage
- Based on Manufacturing
- Based on Type
1. Classification of tiles based on Usage
Depending on the surface on which they are fixed, tiles can be classified as –
- Wall tiles
- Roof tiles
- Floor tiles
- Paver tiles
Wall tiles and floor tiles are used indoors whereas roof tiles and paver tiles are used outdoors.
2. Classification of Tiles based on Manufacturing
- Extruded Tiles (Shaping A) – Tiles whose body is shaped in the plastic state in an extruder, the column obtained being cut into tiles of predetermined length.
- Split Tiles (Split Pattern) – Formed as double tiles that are separated after firing to obtain single tiles. They can be glazed or unglazed and have characteristic parallel ridges on the back.
- Quarry Tiles – Tiles that are cut in succession from a single extruded column and are either pressed or not pressed and are sometimes glazed.
- Pressed Tiles (Shaping B) – Tiles formed from a body reduced to powder or small grains and shaped in moulds at high pressure. They may be glazed or unglazed.
- Cast Tiles (Shaping C) – The body is cast into mould or on to a porous refractory batt that absorbs the water. They can be glazed or unglazed.
3. Classification of tiles based on Type
1. Ceramic Tiles
Ceramic tiles are created made from a mixture of red and/or white clay, sand and other natural substances. The mixture is moulded in the desired shape and size and then fired in kilns at very high temperatures. The resulting material is durable, tough, dense and water resistant. These are then decorated. Ceramic tiles are difficult to stain, easy to clean and their colour doesn’t fade easily.
They are usually used for interior decoration, and where foot traffic is low. Indoors, they are used on walls and floors as they are low in cost and are available in a range of colours and sizes. Indoor ceramic tiles are softer and thinner. When used outdoors, on external walls, the amount of heat absorbed is low, and heat retention is also low. This results in a cooling effect, beneficial during summers.
Ceramic tiles are categorized as –
- Glazed Tile – A glaze is a vitrified covering that is practically impermeable. The baked ceramic tiles are dipped in the glaze solution, which is usually liquid coloured glass, and again baked for a second time so that the glaze fuses with the tile. Lighter glazes are harder than darker glazes. Matte and Satin surface finishes are harder than shiny surface finishes. The glaze holds the colour and the pattern of the tile.
They are stain resistant, water resistant and fire resistant and slip resistant.
But the scratches on the glazed tiles are visible to the eye, and there is loss in lustre/shine after significant use, which is not aesthetically pleasing.
- Unglazed Tiles – These have no glazing and the scratches and dents are not visible easily, unlike glazed tiles. They are used in both commercial and residential areas. They usually have a non-reflective matte finish and often have granular surface.
They are denser, thicker and more slip resistant than glazed tiles, hence suitable for kitchens and outdoors.
They are also more vulnerable to stains, hence, unglazed tiles used indoors need to be sealed using a sealant and a wax, to make them less vulnerable to stains.
2. Vitrified tiles
Vitrified tiles contain silica, quartz, and feldspar (these are the same minerals found in granite) which gives them a glassy texture. The vitrification process makes these tiles highly impermeable to water, hence they do need any glazing. However polished and glazed vitrified tiles are also commercially available.
Before being fire in the kiln at very high temperature, the dye which gives the tile its colour is uniformly mixed with the mixture of clay. This results in a uniform colour throughout the thickness of the tile, unlike glazed ceramic tile which have only a glaze coating on the top surface which contains the colour and the pattern.
They are stronger than ceramic tiles, hence, comparatively more expensive and difficult to install. They are smooth and glossy and require no external glazing. They are more durable than unglazed ceramic tiles. AN extremely low water absorption tile is called a fully vitrified tile.
3. Porcelain tiles
These are more durable and dense than standard ceramic tiles and their water absorption rate is less than 0.5%. They are made pressing moist white clay dust (6-8% water content) under high pressure, which why they are denser and fine grained, making them resistant to staining, water bacteria and odours.
They do not require any polishing, waxing or sealing, hence they are easy to maintain and clean. They are best suited for bathroom flooring. Because they are superior to ceramic tiles, they are costlier. They are also available glazed and in wood patterns, which resemble natural wood flooring.
5. Mosaic tiles
These are tiles which are made by combining small pieces of different coloured pieces of stone pebbles, tiles and glass, usually set in grout or mortar, forming a variegated pattern
6. Concrete pavers / tiles
These are concrete blocks which are the cheapest of all tiles, also they can be laid directly on level ground. They are mainly of interlocking type, which can be easily replaced if damaged. They are mostly suitable for pathways and patios.
Parameters Influencing Selection of Tiles
- Resistance to scratching/abrasion – The Bureau of Indian Standards, in IS 13630 (Part 8) – 2006, has defined the ratings for glazed ceramic tiles depending on their resistance to scratching –
- Class 0 – The tiles of this grade are least resistant to scratches and are hence not recommended to be laid on floors and shall be used as wall tiles only.
- Class 1 – These are the tiles which can be used in areas where very light foot traffic is expected, that is people either walk bare-footed or wear lighter shoes. They are suitable for use in bathrooms.
- Class 2 – These tiles are supposed to be used where light traffic is expected, such as living rooms, bedrooms, study rooms and bathrooms. They however should not be used in halls and corridors.
- Class 3 – These tiles are meant to be used in places where small and medium traffic. They can be used in all the interior spaces of a residential building – bedrooms, bathrooms, living room, study room, kitchens and corridors.
- Class 4 – These are meant to be used in places where normal foot traffic is expected. They can be used in all the premises of a residential building – including the entrances, and passages. They can also be used in small commercial buildings such as small offices, shops, etc. They can have the abrasion resistance of the next higher class, but they are not as resistant to stains as the next higher class.
- Class 5 – These have the highest scratch and wear resistance, and are meant to be used in public spaces such as malls, religious buildings, hospitals, etc.
For use in residential buildings, glazed ceramic tiles having rating of Class 3 and Class 4 are used. Tiles of lower ratings can be used in flooring of spaces which are not meant to be used round the year, or where the estimated foot traffic is low.
- Thermal/Temperature resistance – The tiles to be used outdoors and in kitchens should be resistant to sudden changes in temperature and heat.
- Strength – Strength of the tile is a very important parameter especially when used in flooring and in places where the expected foot traffic is higher than normal, especially in outdoor spaces.
- Chemical resistance – Tiles used in bathrooms, kitchens and outdoors, are exposed to a variety of chemicals, they should be resistant to chemicals (common acids and alkalis) found in most household products. The glazed tiles are rated for resistance against common household chemicals as follows –
- Class AA – no visible effect.
- Class A – Slight change in appearance
- Class B – Definite change in appearance
- Class C – Partial loss of the original surface
- Class D – Total loss of the original surface
- Stain Resistance – Tile are rated as per IS 13630 (Part 8) – 2006, depending on the ease with which the stains on them can be removed.
- Class 1 – are the easiest to clean, they do not require any special cleaning products.
- Class 2 – Stain removed by cleaning product.
- Class 3 – Stain not removed.
- Water Resistance – Water resistance varies depending on the degree of vitrification in case of ceramic tiles and porosity of the exposed surface in case of natural stone tiles. As per IS 13712 – 2006, depending on the water absorption values (E), the tiles are classified as –
- Group 1a – Tiles of Very low water absorption, (E ≤ 0.08%)
- Group 1b – Tiles of Low water absorption, (0.08% < E ≤ 3%)
- Group 2 – Tiles of Medium water absorption, (3% < E ≤ 6%)
- Group 3 – Tiles of High water absorption, (E > 10%)
- Resistance to crazing – A craze is a crack, showing as a fine hairline, or a network of fine cracks, limited to the glazed surface of the tile. Crazing occurs when the glazed surface is subjected to high tension.
- Others – Most tile available in the market are anti-slip. They are used in places where there is possibility of stagnation of water on the tiles, such as bathrooms, kitchen etc.,