Ceramic tiles are one of the most grateful materials in the hands of an architect. Thanks to them, it is possible to create functional and beautiful spaces. Like any material, ceramic tiles have their potential and specification. Depending on the technology of manufacturing and the idea of the creator of the design, they have specific properties and the possible applications resulting from them. They also have specific requirements related to their processing and installation.

How to choose the most suitable tiles for a given place? What parameters should be taken into consideration to ensure durability of the cladding and safety for users? How to make a purchase so that the individual tiles fit together perfectly and the assembly can be executed without problems? Today, we will deal exactly with these issues.

Table of contents

I. The essence of technical parameters in the architecture of the public buildings.

II. The most important technical parameters which are worth paying attention to when designing

1. Anti-slip resistance. The most important parameter in large-area buildings?

2. What is the PEI parameter and how does it affect the durability of the appearance of the tile?

3. Deep abrasion – an ideal solution for public spaces

4. What is rectification and can tiles be laid without grout thanks to this treatment?

5. The tonality of tiles, the way to a unique interior.

6. Frost resistance of ceramic tiles.

7. Differences in shades – what they result from and how to overcome them?

8. What is “caliber”?

9. The classes of stain resistance of ceramic tiles.

10. Chemical resistance

11. Bending resistance and breaking strength

III. Does the perfect tile exist?


I. The essence of technical parameters in the architecture of the public buildings.

Designing public buildings requires knowledge about how the ways of using particular places and the conditions prevailing in them. Complete architectural designs should contain all necessary data regarding the type of materials used.

Depending on the purpose of the given space – the key functions to be used in the ceramic cladding should be taken into account – and according to these functions, you should evaluate and select specific solutions. If there are several functions, it is worth to hierarchise them and select individual parameters of the tiles in accordance with this hierarchy.

For instance, when designing the space of the SPA in a five-star hotel, the anti-slip parameter, resistance to chemicals, as well as aesthetic values and stylistic coherence with the rest of the hotel space will be equally important.

II. The most important technical parameters which are worth paying attention to when designing

Anti-slip resistance. The most important parameter in large-area buildings

Anti-slip parameter, marked with the R symbol, is one of the most important parameters when it comes to the public facilities. The appropriate value of this parameter ensures adequate adhesion to the ground, and thus the safety of people staying in a given facility.
The R parameter specifies the class of anti-slip property of a given tile.

Examination is conducted in two ways:

  • pursuant to the DIN 51130 CEN/TS 16165 (B) standard – the results of anti-slip properties control, specifying the properties of tiles in real life
  • and additionally to the DIN 51097 CEN/TS 16165 (A) (barefoot) standard. This examination is more detailed and specifies the parameters for barefoot walking on a tile covered with water. This standard is mandatory in case of investments with rooms constantly or periodically covered with water and with high humidity, for instance swimming pools and saunas, sports objects, processing plants.
Average value of the acceptable angle [*] Anti-slip class
6 – 10 R 9 – smallest resistance
10 – 19 R 10 – normal resistance
19 – 27 R 11 – good resistance
27 – 35 R 12 – high resistance
> 35 R 13 – very high resistance

Anti-slip test using a platform with a ramp.

Testing the anti-slip effectiveness using a platform with a ramp consists in determining the value of an acceptable angle, i.e. the maximum angle of inclination of the tested tiles, at which a person walking in strictly standardised footwear on the oil-covered surface of the tiles begins to slide.

Anti-slip parameter is represented with the following pictogram:

R 12

ATTENTION: Mud, snow or ice always decreases the anti-slip properties as compared to those declared by the manufacturer.

The type of surface significantly affects the degree of anti-slip property. In the case of unglazed tiles, the structural ones are radically more slip resistant than mirror-smooth polished tiles. It is worth remembering that when deciding on tiles with a structured surface and with higher anti-slip, you will have to put a little more effort into cleaning them than using tiles with a smooth surface.

For areas of particular importance in terms of maintaining adhesion to the ground, additional braking elements are used – such as grooved stair treads, most often mounted on stairs.

Typical stairs in public space. Slip resistance is increased by a special grooved structure of stair treads.

2. What is the PEI parameter and how does it affect the durability of the appearance of the tile?

PEI parameter specifies the class of abrasion resistance of the surface of the glazed ceramic tiles.

It does not apply, however, to wall tiles, decorations or unglazed floor tiles (which are subjected to a deep abrasion examination).

The higher the PEI parameter, the more resistant the tiles will be to the mechanical friction of mineral particles brought home from the outside.

This is one of the most important usable parameters (usually given in the investor’s executive guidelines for the investment), allowing the use of specific type of tiles in a given room.

PEI parameter consists of two elements – for instance, 3/750, 4/2100, 5/12000. The first number determines the abrasion class, the second – the number of revolutions, after which in the examination there is visible change in the surface of the tile caused by the friction.

PEI abrasion class Number of revolutions Classification of glazed tiles
Class 0 100 Tiles of this class should not be used on the floors.
Class 1 150 Tiles approved for use in places where barefoot or soft footwear is used (for example, in bathrooms and bedrooms without direct access from the outside).
Class 2 600 Tiles for application in rooms where soft or normal footwear is used, for example, in living rooms, bedrooms, and bathrooms (excluding kitchens and entrance areas).
Class 3 750
Floor coverings in places where you typically walk in a normal footwear, often with a small amount of impurities (for example, home kitchens, lobbies, corridors, balconies, loggias, and terraces). The tiles are not allowed to be used in places where non-standard footwear is used, for example, ironed-on shoes.
Class 4 2100



Floor coverings, where you usually move with a certain amount of dirt – for example, entrance areas, industrial kitchens, hotels, exhibitions, and showrooms.
Class 5 over 12000 Floor coverings subject to intensified, continuous pedestrian traffic, with certain amounts of dirt stains in extreme conditions – for example, public places such as shopping centres, airports, hotel lobbies, public walkways, and industrial applications.

Ceramika Paradyż is the manufacturer of glazed floor tiles of the abrasion classes ranged between 3 to 5.

In extreme cases of very heavy traffic with a large amount of abrasive impurities, it is recommended to use unglazed tiles, which are characterised by invisible deep abrasion (for instance, technical stoneware).

3. Deep abrasion – an ideal solution for public spaces

If the floor tiles do not have a specified PEI parameter, it means that they belong to the group of the unglazed products, subjected to deep abrasion examination. Its value is determined in Declaration of Usable Properties for a given product. Unglazed tiles, namely technical stoneware or selected clinker tiles, are a good solution for public spaces. Since their structure is homogeneous throughout the cross-section, the process of possible abrasion of the surface is imperceptible on them.

Tiles examination for deep abrasion.

Examination of the tiles for deep abrasion consists in sprinkling a tile, which is placed in the machine, with aluminium oxide and simultaneously subjecting this tile to the process of wiping the groove with an abrasive disc for the time specified in the test. The amount of wiped material is the basis for calculating the abrasiveness of a given tile.

4. What is rectification and can tiles be laid without grout thanks to this treatment?

Rectification is a mechanical treatment of processing the edges of ceramic tiles, which involves milling them at the right angle to the surface of the tile. Both wall and floor tiles can be subjected to this process. Owing to it, all ceramic tiles gain the identical size (with an accuracy of ± 02 mm, so that the rectified floor tiles are not grouped into calibers).

All types of tiles, including rectified ones, should always be laid with a joint and proper dilatation, because only this method of assembly guarantees the elimination of stresses arising due to the linear expansion of the substrate, glue, and mounted tiles. Assembling the tiles without joints can damage the assembled tiles and it can be treated as an error in the construction work.

Rectified tiles are laid with a minimum joint width (1.5 mm), so that using a tile-coloured joint the effect of a uniform ceramic cladding through the entire surface can be easily achieved.

Tecniq silver gres szkliwiony rektyfikowany półpoler, 59,8x59,8 cm
Rectified tiles, laid with a thin joint, allow to achieve the effect of a uniform cladding surface. In the picture: Tecniq Silver collection, glazed porcelain stoneware, rectified, semi-polished, 59.8 x 59.8 cm.

Płytki Tigua bianco
Rectified tiles Tigua Bianco collection, glazed porcelain stoneware, rectified, mat 59.8 x 119.8 cm, Tigua Brown collection 59.8 x 59.8 cm, Tigua Beige collection inserts 29.8 x 29.8 cm.

Agat Naturale i Rosso Gres Szkliwiony Rektyfikowany
Exclusive floor Agat Naturale and Rosso collection, glazed porcelain, rectified, lappato 29.8 x 59.8 cm, 29.8 x 29.8 cm.

5. The tonality of tiles, the way to a unique interior

The tonality of the tiles, inspired by the absolute uniqueness of nature, consists in providing specific tiles with the quality of purposeful, intended uniqueness. Tonality particularly concerns collections imitating natural stones, wood, and concrete.

The tonality is based on the latest methods of decorating ceramic tiles, such as:

  • digital print (for glazed tiles) – tiles manufactured in this technology allow for obtaining the effect of uniqueness for the individual prints. It is not regularly located on each tile and has different discolourations, which is the intended and natural appearance of such a pattern. Print is applied fragmentarily to specific tile formats with subsequent cutting into other dimensions, emphasising the individual elements of the stained print and giving the effect of additional colour variation.
  • double charge (for unglazed tiles)

Owing to these technologies, each tile has a unique pattern and colour. The tonal tiles, laid next to each other, do not create any repeatable pattern, thanks to which the space acquires a unique character.

Tonal tiles are represented with the following pictogram:

The tonality of the tiles provides them with a unique look inspired by the world of nature.

Płytki Arkesia
The tonality of the tiles allows to arrange interiors showing the unique beauty of nature. In the picture: unique tiles of Arkesia collection, in the polished and matt version.

6. Frost resistance of ceramic tiles

For external applications (and sometimes internal ones, where the temperature can periodically drop below zero), only frost resistant tiles are used.

These are the tiles with water absorption (E) equal to or lower than 3%.

These include all tiles manufactured in the following technologies: porcelain stoneware (both glazed and unglazed), clinker, and monocottura.

Frost resistance is indicated with the following pictogram:

The examination determining frost resistance of tiles consists in soaking a tile with water and subjecting it to at least 100 consecutive freezing and thawing cycles.

DUROTEQ Grys Gres Rektyfikowany Matowy
Frost resistant tiles are used as a cladding for terraces and building facades.

Klinkier Cloud Brown
All clinker tiles are frost resistant, which is why they are most often chosen as cladding for elevations, terraces, and garden paths.

klinkier szkliwiony HEXX Universum i kolekcja TAMMI

7. Differences in shades – what they result from and how to overcome them?

The diversified shade of the manufactured tiles is a natural derivative of the physicochemical reactions which occur in the firing process.

  • In case of glazed tiles, the shade relates to the change in glaze.

In Ceramika Paradyż, glazed tiles are manufactured in maximum 5 shades: template, also called WZ (the first batch from a given collection), two lighter versions (A1, A2) and two darker ones (B1, B2).

When purchasing ceramic tiles, it would be best to choose them from the same production batch and with the same shade mark (for example, A1).

If the seller does not have a sufficient number of tiles in the desired shade, you can eventually try to combine tiles and decorations with adjacent shades – for instance: (A and A2), (A2 and WZ), (WZ and B1) or (B1 and B2). The condition is, however, a personal, visual assessment of the differences and making an informed decision.

This is best seen in the diagram:

Terminology for marking the shade of glazed tiles.

It is not recommended to combine tiles with different shades because the differences in colouring will be visible after assembly, which will in turn significantly reduce the aesthetic value of a given space.

  • In case of unglazed tiles, the shade relates to the ceramic mass, therefore it depends on the charge of the mixture of minerals used during the manufacturing process.

During the manufacturing process of the unglazed tiles, i.e. some clinker and porcelain stoneware collections, the number of shades is not limited because every production batch is characterised by different dyeing. Each subsequent production batch is assigned a number from A1 to Z99.

Marking of the shade of unglazed tiles is completely different than in the case of glazed tiles – when purchasing them, we cannot associate their proximity with the mark, for example A21 and A22, as it is not related to the actual appearance of the tiles. Each production batch is characterised by its colouration, which is conditioned by the raw materials which were created by nature.

It is worth mentioning that for products manufactured from mixtures of multicoloured pellets, which are produced from fossil raw materials, the colour variation of the tiles takes place. These pellets in a loose form are properly served on the press and they are arranged in a variety of random and unique patterns on the surface of the tile, where the diversity in its graphics is the intended decorative effect.

When selecting unglazed tiles for a given room, it would be advisable to choose them from one production batch. Then, we would have a guarantee of obtaining a uniform surface.

If it is necessary to combine tiles from different production batches in one room, it is best to make a selection in person, carefully assessing the appearance of the tiles in the light in which they will eventually be assembled.

The study of differences in shades results from the minimal differences in the colour of raw materials.

Differences in the shades of tiles result from minimal differences in the colour of the raw materials supplied.

8. What is “caliber”?

Caliber is the indication of the assignment of a given floor tile to a group from a given dimensional range (defined by standards).

The caliber parameter is a derivative of the phenomenon consisting in shrinking of the ceramic mass under the influence of high temperature (the tile in the firing naturally shrinks by an average of 10% in the firing process). This results in the fact that ceramic tiles may differ slightly in dimensions.

A caliber symbol is placed on each package of floor tiles and it is especially important when making orders or in retail purchase.

It is absolutely necessary to follow the laying of tiles in a given room with the same caliber (and preferably also shade). Tiles with different calibers should not be laid on the same surface.

Examples of the range of calibers:

9. The classes of stain resistance of ceramic tiles.

For some applications of ceramic tiles, stain resistance may be of particular importance. It is defined by classes on a scale of 1 to 5 – the higher the class, the higher the resistance.

In laboratory tests, staining substances such as olive oil, alcoholic iodine solution and green staining agent in oil are used, among others.

Stain resistance class The method of removing stains, thanks to which the test tile is cleaned
5 Stains removed only with running water at 55 ± 5 ° C for 5 minutes.
4 Stains removed with sponge and a mild cleaner with a pH between 6.5 and 7.5.
3 Stains removed with a strong cleaner with a pH between 9 and 10, with the use of a rotary brush with a diameter of 8 cm with hard bristles for 2 minutes at 500 rpm.
2 Stains can be removed by immersing the tile in a suitable solvent (3% hydrochloric acid, potassium hydroxide solution of 200 g/l, acetone) for 24 hours. Then, the surface is rinsed vigorously under running water. If one of the solvents removes stains, the cleaning has to be considered as valid.
1 Stains not removed with any of the abovementioned method.

Stain resistance test.

Staining test is carried out by applying colouring substances onto the tile. After 24 hours, the tile is washed – initially only with running water, and then with more and more powerful means, until the surface is completely cleaned. Depending on where the cleaning process ends, this resistance class is given to the tile.

10 . Chemical resistance

Chemical resistance to which tiles are subjected to in testing is determined with classes – from A (the highest) to C (the lowest).

Class A – no visible changes

Class B – visible changes occur on the cut edges

Class C – visible changes on the surface and cut and uncut edges of the tile.

The samples of ceramic tiles are subjected to testing according to the EN ISO 10545-13 standard from 1 to 4 days, in ambient temperature, and with the usage of the following testing agents:

  • Household chemicals – ammonium chloride solution of 100 [g/l].
  • Swimming pool salts – sodium hypochlorite solution of 20 [g/l], prepared from technical grade sodium hypochlorite with about 13 % (m/m) of active chlorine.
  • Acids and alkaloids at low concentration (L):
    • Hydrochloric acid solution at 3% prepared from concentrated hydrochloric acid,
    • Citric acid solution of 100 [g/l],
    • Potassium hydroxide solution of 30 [g/l].
  • Acids and alkaloids at high concentration (H):
    • Hydrochloric acid solution at 18%, prepared from concentrated hydrochloric acid,
    • Lactic acid solution at 5%,
    • Potassium hydroxide solution of 100 [g/l]

The possible changes on the surface and edges of the tiles are subjected to the visual assessment.

Chemical resistance according to the EN ISO 10545-13 standard
Resistance to acids and alkaloids at low concentration – unglazed tiles Manufacturer provides specification
Resistance to acids and alkaloids at high concentration Test method
Resistance to household chemicals and additives to swimming pool water – unglazed tiles Minimum UB

Examination of chemical resistance of tiles.

The chemical resistance of tiles is tested by inserting the sample into the container with the solution and leaving it for 1 to 4 days. After this time, we observe whether any changes have occurred on the tested sample.

11. Bending resistance and breaking strength

Specifying the rupture resistance with the measuring of the coefficient method is carried out according to the PN-EN ISO 10545-4 standard.

The standard specifies the method of performing the test of mechanical bending strength of tiles. Bending strength is expressed in N/mm2 achieved by dividing breaking strength expressed in N by section area at the breaking spot.

The obtained results are expressed as average values of bending resistance and breaking strength respectively, while only the results of tiles which broke in the middle of its length are taken into consideration.

Tiles testing machine for resistance to bending.

Minimum requirements of the standard for particular types of tiles:

  • Monoporosis
    • Breaking strength – 200N – tiles with the thickness <11mm
    • Breaking strength – 600N – tiles with the thickness >11mm
    • Bending resistance – 15N/mm2
  • Porcelain stoneware
    • Breaking strength – 1300N
    • Bending resistance – 35N/mm2
  • Clinker
    • Breaking strength – 1100N
    • Bending resistance – 30N/mm2

III. Does the perfect tile exist?

The perfect tile is the one which will provide durability, safety, and appropriate aesthetic qualities for a given space for many years. Tiles – depending on the production technology and the idea of designers – have different characteristics.

The key function which tiles should play in a given place is always the most important. Is it supposed to be a decorative function? The function of protection against moisture in rooms with high humidity? Function of protection against chemicals or staining? Is it safe from uncontrolled slipping? Or maybe it has to be a heat transfer function for solutions with underfloor heating?

The perfect tile is the one which satisfactorily for the investor and users fulfils all the tasks entrusted to it – often mutually complementary.


  1. Anti-slip resistance, marked with the R symbol, is one of the most important parameters in large-area buildings.
  2. The PEI parameter defines the resistance class for surface abrasion of glazed floor tiles (the higher the class and the number of revolutions, the greater the amount of traffic with abrasives the tile can withstand).
  3. Unglazed tiles which undergo the invisible deep abrasion are a proven solution for public spaces with high traffic, thus with a large amount of abrasive substances.
  4. Rectification is a specialised milling of the edges of tiles, unifying the size of tiles and allowing them to be laid with a minimal joint.
  5. The tonality of ceramic tiles allows for designing the unique spaces due to the intended effect of the uniqueness of the appearance of individual tiles from a given collection. The variation in tile graphics is the intended effect.
  6. Frost resistance is a key parameter for external or internal applications in which the temperature can periodically fall below zero.
  7. When purchasing for a given room, it would be best to choose tiles from the same production batch, marked with the same shade symbol.
  8. When purchasing non-rectified floor tiles for a given room, only tiles marked with the same caliber have to be selected.
  9. The stain resistance class is determined on a scale of 1-5 (the higher, the better).
  10. The chemical resistance class is marked with a letter symbol on a scale from A (highest resistance) to C (lowest resistance).
  11. An ideal ceramic tile is the one which meets all utility and aesthetic functions for a given application, in a sustainable and satisfactory way for both the investor and users.


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