1. Tiling - what do you need to know?

1.1. Standard

There is an international standard for the categorisation of ceramic tiles known as SIST EN ISO 14411. It classifies tiles by the method of manufacture (A – extruded, and B – dry-pressed) and by their water absorption capacity (E). They are further divided into internal and external tiles and floor and wall tiles. The standard has annexes that specify dimensions (length, width, thickness), physical characteristics (impact resistance, freeze-thaw resistance, etc.), as well as chemical characteristics (resistance to staining, chemicals, etc.).

The standard also specifies how tiles should be marked during manufacture: floor tiles have a shoe print marked on the packaging, while wall tiles have a hand print; in addition, there is a serial number, an abrasion resistance mark (PEI), and a snowflake showing frost/thaw resistance.

1.2. Correct selection of tiles according to their purpose

It is very important to choose tiles which are fit for purpose, so think carefully about the following factors. The first is the location – where these tiles will be laid (outside, inside, on a floor, on a wall). Next is the backing surface the tiles will be put on – whether the new tiles will be placed over existing ones, on a brick wall, on concrete blocks, screed, cement mortar, or chipboard, etc. The most important thing here is the quality of the underlayment and whether it will be able to support the weight of the adhesive and tiles. The third factor is the size and shape of the surface to be tiled; then there is the load – certainly, the load that tiles have to withstand in a living space is different from those on a factory floor, for example. The last factor, but no less important, is how the tiles will be laid – with a thin-layer of adhesive or on cement mortar.

Tiles are divided into the following categories according to the characteristics they must have in relation to their purpose:

PEI 0: for walls only;

PEI 1: for floors in rooms that do not get dirty or have no direct access from outside, such as residential bathrooms and bedrooms;

PEI 2: for floors in rooms like living rooms where only bare feet or soft-soled footwear are used. Therefore, they are not suitable for kitchens, corridors, or similar areas subjected to considerable traffic;

PEI 3: for entrance halls, corridors, kitchens, balconies, and terraces – in other words, areas that are more exposed to dirt;

PEI 4: for residential and light commercial floors that are constantly exposed to some dirt such as entrances, lobbies, showrooms, shops;

PEI 5: for floors that are exposed to constant and significant dirt – shopping malls, petrol stations, hotel foyers, factories, and the like.

2. Different types of tiles

2.1. Ceramic tiles

Ceramic tiles are made of kaolinite, sand, and clay (brown, red or white), as well as some other ingredients. The mixture is pressed into steel moulds at high pressures and then baked in kilns at temperatures of over 900°C. A glaze is applied to most tiles to give them a colour or pattern. Ceramic tiles are more porous, absorb moisture and crack more easily, are weaker and less resistant. For this reason, they are not suitable for external surfaces or internal surfaces that are exposed to heavy use. The glaze cracks and chips easily, leaving just the bare clay. However, for these same reasons, they are easier to cut and fit and they are cheaper than porcelain tiles.

2.2. Porcelain tiles

Porcelain tiles are considered to be the most robust type of tile; they are waterproof and do not freeze, so they can be used for external surfaces. Even so, nowadays, most interior tiles are porcelain as well. In England, they are commonly known as stoneware tiles. They are made of fine sand, ground stone, pigments, and high-quality kaolin clay, which acts as a binder. The tile mixture is pressed into moulds under high pressure and then baked at temperatures of over 1200°C. A cross-section of the tile reveals that it is of uniform structure and therefore is firmer than ceramic tiles. Unlike ceramic tiles, they are not glazed, but their surface can be treated in various ways, so they come in different finishes: polished, honed, natural, grip, structured, and so on. The PEI rating of these tiles is always 5. For the same reason, they come in a vast array of dimensions – from mosaic-sized to 3 m. They are usually 10 mm thick. However, the larger dimension tiles are sometimes only 3 mm thick, but they can be reinforced with glass wool.

2.3. Glass tiles

As with the other types of tiles, glass tiles come in different shapes, sizes and colours and are used for different purposes, most often as wall coverings or decorations. Some are made of recycled glass, so they are eco-friendly in addition to being visually very interesting. It says it all that they were used for mosaics as far back as 8,000 BC.

2.4. Cement tiles

Cement tiles are used for flooring in low-stress and low-traffic residential and public areas. Unlike ceramic tiles, cement tiles get their strength through the process of dehydrating Portland cement instead of baking a clay mixture. Cement tiles can best imitate the rustic styles of the 19th century, when they were most popular, since they were painted with pastoral scenes in bright colours. The images were usually hydraulically pressed into the surface. Cement tiles are smaller in size and thicker than ceramic and porcelain tiles and can be square, rectangular, or polygonal.

2.5. Natural stone tiles

Natural stone tiles are incredibly strong and durable, especially if they are made of granite, which is almost indestructible. Other commonly used types of stone are marble and limestone, but they are softer and weaker. The upkeep and cleaning of natural stone tiles is simple. Their only possible drawback is that they are cold and hence are not often used for residential floors. However, they are ideal, and hence most commonly used, for walls, in addition to bathroom and kitchen flooring. Granite tiles are excellent for heavy-traffic areas in public buildings. Stone tiles can also be used for exterior walls and flooring.

3. Tiling methods

Although many people think tiling is simple, this couldn’t be further from the truth. We recommend you contact an expert, particularly if you don’t have any experience. This way you’ll avoid any possible complications and the final result will be one you’re thrilled with.

3.1. Preparation of the backing surface

The first and most important step in the tiling process is to prepare the backing surface. The underlayment must be solid enough to support the weight of the material and also the intended load, and must be perfectly level; if it isn’t, various traditional or self-levelling mixtures can be used to remedy this. Ceramic tiles are laid on surfaces that are dry and clean and the tiles themselves must be in the same condition, so they are also cleaned and dried if necessary. A primer that reduces water permeability is applied to the prepared backing surface. If tiles are to be laid in a bathroom or similar ‘wet’ rooms, a waterproof coating is also a must.

3.2. Dimensioning and layout

When the underlayment has been properly prepared, the entire space must be measured up and the layout of the design must be planned. First, the surface area of the underlayment is measured in order to know how many tiles are needed, but an additional 10% is factored in – this is to allow for breakages, cuts, and wastage. It is best to start tiling from the middle of the space. First, a vertical row is marked using a gauge rod, spirit level, and tape measure. Once the vertical rows have been established, the process is repeated for the horizontal rows. Wooden battens can be secured to the surface as a guide. It is always advisable to fit wall tiles before floor tiles, trying, if tile dimensions allow, to line up the tiles so the floor tiles look like a continuation of those on the wall, like an unbroken line. It is also recommended to arrange the tiles first before using any adhesive, especially if the design involves a pattern. Once the layout is to your liking, it’s a relatively simple job to start fixing the tiles.

3.3. Cutting tiles

Tiles are cut with a manual or electric cutter. When the tile has been scored, it can be cut using tile nippers or a snapper to remove the unwanted part of the tile. To make round holes in tiles (to go round pipes, for example), a circular holesaw attached to a drill is used or special clippers that break off smaller pieces of tile.

3.4. Laying the tiles

When the final layout of the tiles has been decided upon, a thin layer of adhesive is applied to the back of the tile and a ridged surface is made with a notched trowel. The ceramic tile is then applied to the wall or floor, pressed into place, and then tapped with a rubber hammer to ensure it sits well. In order for the tiles to be placed precisely, plastic tile spacers are put between them, which creates a gap of between 2 mm and 1 cm. When the whole surface has been tiled, the adhesive has to dry for at least 12 hours.

3.5. Grouting

The final step in installing tiles is grouting. The grouting mixture is usually in the form of a powder and should be mixed with water following the manufacturer’s instructions. It is applied with a spatula or grout float, diagonally over all the tiles so that all the gaps are completely filled, from top to bottom and from wall to wall. Any grouting mixture left on the tiles can be wiped off, along with any other traces of adhesive before it hardens. The easiest way to do this is to use a sponge soaked in clean water. If there is any residue that cannot be wiped off with water, there are special cement removers or thinners available. Corner, expansion, and connecting joints are not filled with cement grout, but with a special elastic silicone sealant. Before applying the sealant, adhesive tape is placed around the joints.