Guide to ceramic wall and floor tiles

What should I bear in mind before buying ceramic tiles?

Before purchasing any product, we recommend carrying out an analysis or assessment of it to build up a knowledge base and, ultimately, to avoid making the wrong choice and encountering problems with the material once it has been laid. Ceramic tiles come in a wide variety of styles, and there is a vast range of options available on the market. Below, we outline the key points you should bear in mind before buying ceramic tiles.

1. WHERE AM I GOING TO LAY THEM?

This is the first question you should ask yourself and the starting point for your decision. Depending on this, all the characteristics the tiles must have to ensure you make the right choice will be determined.

You’ll need to consider whether they’re for outdoor or indoor use, and whether they’re for floors or walls.

2. WILL IT BE SUBJECT TO HEAVY FOOTFALL OR NORMAL WEAR AND TEAR?

We must consider whether, due to its location, the tiles will be subject to constant foot traffic, heavy traffic, wear and tear from rough footwear, or exposure to potential stains. All these factors must be assessed to determine the minimum requirements regarding scratch resistance, abrasion resistance, slip resistance, etc.

What properties or characteristics should a ceramic tile have?

Generally speaking, there are four key properties you should be aware of in a ceramic tile:

1. WATER ABSORPTION

The first and most important is water absorption. Together with the colour of the raw material, this is the quality that gives ceramic tiles their name. Furthermore, properties such as frost resistance also depend directly on it. They are known by the following designations:

2. FROST RESISTANCE

It is essential to know whether the tiles to be laid will be frost-resistant or not. This property is necessary for outdoor installation.

To determine this characteristic, the ISO 10545-12 frost resistance standard is followed, which involves subjecting a sample – after first immersing it in water – to 100 cycles of temperature changes between -5°C and +5°C. If no damage is observed, the tile is deemed ‘frost-resistant’.

3. SLIP RESISTANCE

This is a characteristic specific to floor tiles and refers to the ability of ceramic tiles to resist slipping or sliding.

There are three classes of slip resistance (Rd) defined by the standards:

• Rd ≤ 15 Class 0
• 15 < Rd ≤ 35 Class 1
• 35 < Rd ≤ 45 Class 2
• Rd > 45 Class 3

See the minimum classes required for flooring depending on its location:

Dry inland areas:

• Surfaces with a gradient of less than 6 per cent – Class 1
• Surfaces with a gradient of 6 per cent or more and staircases – Class 2

Damp indoor areas (building entrances, covered terraces, changing rooms, showers, kitchens):

• Surfaces with a gradient of less than 6% – Class 2
• Surfaces with a gradient of 6 per cent or more and staircases – Class 3

Indoor areas where, in addition to water, other substances (fats, lubricants) may be present, such as commercial kitchens, abattoirs, industrial premises, etc. – Class 3

Outdoor areas. Swimming pools and showers (areas intended for barefoot users and at the bottom of pools where the depth does not exceed 1.5 m) – Class 3

4. RESISTANCE TO WEAR, ABRASION AND SURFACE HARDNESS

Resistance to wear and abrasion: This is the method for measuring the ability to conceal wear caused by abrasion, such as that caused by footwear.

There are 5 levels:

• Level 1 – Low
• Level 2 – Medium
• Level 3 – Medium-High
• Level 4 – High
• Level 5 – Very High

Hardness or scratch resistance: To determine hardness or scratch resistance, a test is carried out by scratching the surface with the 10 materials on the Mohs scale in ascending order. The minimum requirement for wall tiles is Mohs 3 and for floor tiles is Mohs 5.

Other aspects to bear in mind with ceramic tiles

1. TYPES OF STONEWARE ACCORDING TO RAW MATERIAL

The differences between them stem mainly from the clays used, their natural colour and their treatment, which give each material its distinctive characteristics. If you have any queries about which type is most suitable, please do not hesitate to contact us.

• Red Body. This is the most common and economical type of stoneware; its name derives from the clays used in its composition, which have reddish hues. A layer of coloured glazes is applied to the clay base to give the tile its appearance.
• White Body. Its name also comes from the clays used in its composition, which in this case are whitish in colour. Suitable for both indoor and outdoor use, it may or may not feature a layer of glaze, such as in the case of rustic extruded tiles.
• Porcelain Stoneware. It is made from the same types of clay and sandstone throughout, but is pressed to a greater degree, giving it the highest strength on the market.

2. RECTIFIED TILE

Standard ceramic tiles have rounded edges, which necessitate the use of grout; rectified tiles, however, are cut using a pressurised water jet directed at the raw tile, resulting in tiles with perfectly straight, cross-cut edges.

When these tiles are laid, the gaps between them are virtually imperceptible. Even so, we always recommend leaving a minimal joint to accommodate the expansion and contraction that all materials undergo due to temperature changes.

3. THICKENED VITREOUS WARE

Whilst it does not match the characteristics of porcelain stoneware, it offers the following advantages that make it suitable for outdoor use:

• Minimal water absorption
• High breaking strength
• High resistance to scratching and abrasion
• Resistance to frost and thermal shock

4. WHAT ARE SHADE AND SIZE?

Due to the inherent characteristics of ceramic material and the chemical and firing processes involved in its manufacture, it is virtually impossible for two production runs of the same model, carried out at different times, to be 100 per cent identical.

This is why, for the same model, different production batches may result in variations in shade and calibre, where ‘shade’ refers to the appearance or look of the product and ‘calibre’ refers to the thickness of the piece.

We recommend purchasing complete batches containing sufficient product for your installation, and if you are buying the same model on different occasions, always enquire about the shade and thickness.

5. SHADE VARIATION OR COLOUR DISCREPANCY

We must not confuse colour variation with colour shade and/or thickness.

By ‘shade variation’ we mean the intentional variation in shade resulting from the design of the pieces and the model itself.

As an example, we have provided several possibilities that may be encountered, with varying degrees of colour variation.

6. CERAMIC PIECES

There is a wide variety of special components.

By way of example, we list the most common ones relating to steps:

Optimise results with the following information

Once you have decided on the product that best suits your requirements, both practical and aesthetic, you should be aware that you can still improve your purchase by optimising costs on complementary items as well as the performance of the ceramic tile itself through proper installation.

1. HOW MUCH MATERIAL DO I NEED?

Measure the square metres of the room or space; if there are out-of-square or diagonal edges, we recommend basing your calculation on the maximum measurements to avoid running short of material at the last minute.

It is important to add between 10 per cent and 15 per cent to the total square metres calculated, to allow for broken or wasted tiles and cuts needed to fit around uneven wall edges.

2. WHICH MORTAR IS THE RIGHT ONE?

There are currently a multitude of brands on the market and a wide variety of mortars. We recommend that you ask us if you have any doubts about choosing the right adhesive; to this end, we provide, in the ‘Mortars, Cements and Aggregates’ section, a wide range of tile adhesives specifically designed for each type of ceramic tile, their characteristics and the environment in which they will be laid. For each product, you’ll find a user and application guide detailing all the products and installation systems.

3. HOW DO I LAY THE TILES CORRECTLY?

Firstly, we must assess the condition of the substrate on which the tiles are to be laid; check that it is strong, clean, sufficiently level, absorbent and rough, and that it is also stable. Next, prepare the adhesive mortar and apply it: A) in a thin layer (for substrates with good flatness) using a notched trowel, or B) in a thick layer (for substrates with poor flatness) using a trowel or float. Adhesive cements must not be used in a thick layer; therefore, you must first prepare the substrate to be able to use them.

To ensure correct installation, we recommend using ceramic levelling systems, which ensure that the tiles lie flat relative to one another once the tile adhesive has set.

Finally, after 24–48 hours, grouting should be carried out using a grout-type mortar or a special jointing mortar, which you can also find on our website.

Correct installation and maintenance of wall and floor tiles

1. INSTALLATION IN INTERIORS

1. It is essential that, before beginning installation, the substrate has cured and is perfectly dry and hardened (with all shrinkage due to setting having taken place), to prevent the occurrence of problems such as lifting or cracks resulting from a lack of stability.
2. Before installation, check the quality, colour and size of the tiles, and ensure the material is free from any visible defects. To achieve the best decorative effect, mix tiles from several boxes. Handle the material carefully to avoid chipping or flaking of the tile edges.
3. Under no circumstances should the tiles be wetted or submerged in water prior to laying, nor should they be laid using traditional mortar (thick-bed method). Lay the tiles using the thin-bed method with a notched trowel and tile adhesive of at least type C1 (standard EN 12.004). For large formats (with one side longer than 40 cm), use the double-adhesive method. Strictly adhere to the tile adhesive manufacturer’s instructions for use: method, mixing time and water ratio, open time for laying, etc.
4. Joints of at least 1.5 mm are required. Ensure that the adhesive has fully set before grouting. Fill these joints with a specific grouting material to prevent any potential water ingress. Do not use lime, mortar or any type of cement-based grout.
5. If you wish to lay the tiles in a staggered pattern, never stagger more than 15 per cent of the longest side of the tile (for example, for 12.8 x 65 format tiles, do not stagger more than 15 per cent, i.e. approximately 10 cm).
6. If any additional building work is required, the floor must be protected to prevent scratching by any abrasive objects.
7. After installing and grouting the tiles, remove any remaining adhesive or grout using a product specifically designed for cleaning construction residues (scaling remover or cement remover), strictly adhering to the usage instructions and concentrations specified by the manufacturer. In any case, we recommend that, before using any chemical product, you test its effects on an inconspicuous area of the tile.
8. For daily cleaning of the tiles, use only hot water and a household detergent or diluted ammonia. Do not use aggressive products or products containing acids, particularly sulphuric acid or hydrofluoric acid.

2. INSTALLATION AND MAINTENANCE OF SPECIAL PIECES

Our catalogue includes special tiles that are not made of ceramic; they may be made of marble, glass, metal, resin, etc. Please pay particular attention to the installation and cleaning instructions enclosed in the boxes for each of these items. Particularly with this type of item, do not use harsh cleaning materials (abrasive scourers, hydrochloric acid or acid-based cleaning agents).

3. OUTDOOR INSTALLATION

Outdoor installation is particularly critical; therefore, in addition to the general installation requirements, it is essential to follow specific requirements for outdoor installation. If installation is to take place in an AREA AT RISK OF FROST, use only PORCELAIN tiles; under no circumstances should stoneware or red-body or white-body wall tiles be used. In all cases, the following installation requirements must be met.

1. When laying floor tiles, a minimum slope of 2 per cent is required to facilitate water drainage. It is also necessary to install a drainage layer and a drainage pit beneath the tiles.
2. Use C2-type tile adhesive (in accordance with standard EN 12.004). Lay the tiles using the double-adhesive method, ensuring they are properly compacted to prevent air pockets forming beneath the tiles.
3. Leave a minimum joint width of 5 mm. Use a grouting material specifically designed for outdoor use (type CG2 in accordance with standard EN 12.004).
4. Observe structural and perimeter joints. Install expansion joints every 10–20 m².
5. Pay particular attention to the junctions between the tiles and other elements such as columns, walls, railings, etc., ensuring the necessary joints are provided to prevent water ingress.

4. LAYING RECTIFIED TILES

Although the installation requirements are the same as for any type of tile, rectified tiles are particularly delicate, especially at their corners and edges; therefore, the installation of this type of tile is particularly critical and, in addition to the general installation requirements, special attention must be paid to the following:

1. The flatness of the installation substrate is of the utmost importance. The surface on which the tiles are to be laid must first be levelled.
2. Handle the tiles with care to prevent chipping or cracking at the edges.
3. Do not immerse the tiles in water, as their flatness may be affected once they become damp. Lay the tiles using a thin-bed method with cement (type C1 for interiors and type C2 for exteriors – in accordance with EN 12.004).
4. Always leave a minimum joint width of 1.5 mm.
5. If you wish to use a staggered laying pattern, never do so over more than 15 per cent of the tile’s length.