While slip-resistant tiles are mandatory in public and commercial areas, there is no obligation whatsoever for the private sector. However, why you should also pay attention to the slip resistance of your tiles in your own four walls and how you can ensure the necessary slip resistance, you will find out in the following article.

Watch out, danger of slipping!

Universally applicable and hard-wearing, yet at the same time visually appealing and easy to clean: a floor covering made of tiles offers many undisputed advantages. If it weren’t for this small but sometimes momentous downer.

Tiles can quickly become quite smooth in wet or damp conditions. This is because water, grease and dirt significantly reduce the static friction coefficient of the surface. Especially in the bathroom, around the pool, on the terrace or even in the kitchen, one wrong step is often enough to lose your footing.

This is not only annoying, but above all can be dangerous. According to accident statistics, insufficiently slip-resistant floors are one of the most frequent causes of falls and injuries. A good reason, therefore, to attach importance to sufficient safety in areas with increased risk of slipping.

Non-slip tile: That’s what counts

Although slip-resistant tiles are not a must in the private sector, they are the best prevention against accidents. It is therefore best to pay attention to the slip resistance of tiles as early as the planning and purchasing decision.

Material and format

The material or the structure of the surface already gives a first visible hint. In general, the rule is: the rougher a tile is, the higher the slip resistance. For example, untreated natural stone or porcelain stoneware tiles are inherently relatively slip-resistant, while glazed, impregnated or high-gloss polished tiles are generally less able to meet the requirements.

The size of the tiles also has an influence on slip resistance: with smaller formats, the proportion of joints on the floor surface is higher – and this also has a positive effect on slip resistance. This is one of the reasons why mosaic tiles are often used, especially in areas with an increased amount of water (e.g. showers or swimming pools), as the many joints give the floor a kind of braking effect.

Anti-slip classes according to DIN standard

However, it is not possible to determine at a glance how slip-resistant the tile actually is. Much more decisive is therefore the marking based on standardised slip resistance classes. However, these have nothing in common with the tile abrasion group.

Although these are primarily important for compliance with the legal requirements for non-slip tiles in the commercial or public sector, they naturally also offer private consumers a reliable guide to help them choose the right tiles.

Assessment of slip resistance: Tiles in test procedure

As with any other floor covering, the assessment of the slip resistance of tiles is carried out according to a special procedure: the so-called walk on sloping ground. In order to determine the static friction coefficient of the tiles, an expert test person from the tile manufacturer walks back and forth on the surface to be tested, whereby the angle of inclination of the tile is increased more and more by lifting it to one side. Depending on the commercial sector in which the floor covering is to be used, the test is carried out either with footwear on oil or barefoot on water, in order to simulate as real a use as possible. As soon as the test person begins to slip or become unsteady on the prepared surface, the test ends.

Classification according to evaluation groups

Based on these results, slip-resistant tiles are now assigned to the corresponding evaluation groups R9 to R13 according to DIN standard 51130 as follows

Class R9:

low coefficient of static friction, safe to step on at an angle of inclination of 6 – 10°, suitable for e.g. living rooms, interior stairs, entrance areas etc.

Class R10:

normal coefficient of static friction, safe to step on at an angle of inclination of 11 – 19°, suitable for e.g. outdoor stairs or tiles in outdoor areas, bathrooms, balconies / terraces etc.

Class R11:

increased coefficient of static friction, safe to step on at an angle of inclination of 20 – 27°; suitable for e.g. outdoor installations,

Class R12:

high coefficient of static friction, safe to step on at an angle of inclination of 28 – 35°, suitable for e.g. cold stores, hospitals, canteen kitchens

Class R13:

very high coefficient of static friction, safe to step on at an angle of inclination of over 35°, suitable for e.g. workshops, slaughterhouses, production halls etc.

If the floor covering is also suitable for use in so-called wet barefoot areas according to DIN 51097, an additional value is added to the tiles:

Class A:

very low slip resistance, slip resistance up to an angle of inclination of 12°, suitable for dry to maximum wet floors

Class B:

medium slip resistance, slip resistance up to an angle of inclination of 18°, suitable for wet floors

Class C:

high slip resistance, sure-footed up to an angle of inclination of 24°, suitable for swimming pools

What slip resistance tiles need in private homes

Depending on the slip class to which tiles are assigned, this results in the possible areas of application. However, it must always be kept in mind that the evaluation groups apply primarily in the commercial sector – and there the requirements for tile slip resistance are much higher than in private use. In addition, with tiles of higher slip-resistance classes, the cleaning effort also increases because the surface is rougher. The motto with regard to surefootedness at home is therefore: less is often more.

For normal domestic use, therefore, tiles of the R9 and R10 rating groups are usually laid. Even their “low” to “normal” coefficient of static friction usually meets the requirements for adequate slip resistance completely without the floor covering losing its attractiveness and comfort.

In sanitary rooms or outdoor areas, a higher degree of slip resistance can be achieved, if required, by using rating groups “B” or “C” and with tiles R10 and R11. Especially if people often walk barefoot there, this can of course be highly recommended. Class R12 and R13 tiles, on the other hand, are basically designed for special, mostly industrial areas and are therefore no longer relevant for private use.

Making smooth tiles non-slip

Ideally, the slip resistance is therefore already taken into account during the planning or laying phase. But even if it only turns out afterwards that certain areas are too slippery, this does not necessarily mean that the leg is broken. After all, even in retrospect there are various methods of improving slip resistance:

  • A simple but very effective option are self-adhesive anti-slip strips. These are simply stuck onto the smooth areas at specific points and thus provide more grip. They are particularly suitable for stair steps, but can also be used in wet areas.
  • In order to increase the slip resistance on larger surfaces, adhesive coverings and foils are suitable, which can also be applied relatively easily.
  • In addition, there are special anti-slip coatings or varnishes with which the entire surface can be provided.
  • Another possibility is to treat the tiles mechanically (e.g. by sandblasting or compressed air technology), chemically (e.g. fluorine, chlorine or ammonium compounds) or with laser technology and thereby additionally roughen the surface.

The abrasion group plays an important role in the search for the right floor tiles. This is because it shows how well the product can withstand daily stress. In the following article you will find out into which abrasion classes tiles are classified and for which areas they are therefore suitable.

Whether in private living areas, for commercial use or outdoors – tiles are generally regarded as extremely robust and hard-wearing. Provided, of course, that they are actually able to cope with the daily stress in the respective area. The decisive criterion in this context is how much abrasion tiles produce – and there are sometimes quite big differences.

Glazed vs. unglazed tiles: Abrasion depends on the surface

Unglazed tiles are usually indestructible even under the highest stress and strain. The special manufacturing process makes the material as hard as diamonds and therefore resistant to surface damage and wear. In addition, unglazed tiles also score points in terms of slip resistance due to their rough surface. This means that they can be used in any area and in all rooms without any restrictions, without having to pay particular attention to slip resistance or abrasion resistance.

In contrast, abrasion is much more relevant for glazed tiles. The glaze makes the surface much more sensitive to external influences. This can not only lead to reduced slip resistance in wet or damp conditions, but over time also to wear and tear. These traces of use are often visible in the form of a loss of shine in the affected areas, particularly in the case of scratching dirt and grinding or rubbing movements when walking on the floor with shoes. And this in turn sometimes leads to limitations in the possible areas of application. Not least for this reason, ceramic glazed tiles are also assigned to an abrasion group according to DIN EN 10545-7.

Quality criterion abrasion class: Tiles in endurance test

In order to be able to assess the resistance of the surface to wear and tear, glazed tiles are therefore tested for their resistance to abrasion in a standardised test procedure. A machine produces artificial abrasion by rotating steel brushes with the addition of water and abrasives until the surface of the tiles visibly changes. Depending on how many rotations this is the case, the tiles are divided into abrasion groups 1 to 5 according to DIN EN 10545-7.

Which abrasion group tiles should have

The abrasion of glazed tiles depends both on the glaze itself (hardness, thickness, degree of gloss, etc.) and on the frequency of foot traffic, the degree of soiling and the type and intensity of use in the area in question.

All these factors are also taken into account in the abrasion class, which is why it is a decisive quality and selection criterion for tiles. In order to find out whether the tiles are suitable for the planned location, it is therefore worthwhile to pay attention to these classes when buying. The following overview shows what the respective tile abrasion class means in detail.

Abrasion groups at a glance

Abrasion group 1:

Tiles in this class are only suitable for very light use. The surface rubs off quickly and is extremely sensitive to scratching dirt. The recommended use for these tiles is in principle as wall covering. As floor coverings, they are only suitable – if at all – for rooms that are mainly walked on barefoot or only with very soft soles, such as slippers, when there is little foot traffic (for example bedrooms or bathrooms). Due to their low resistance and limited application, however, tiles of abrasion group 1 are generally only rarely offered by the tile manufacturers.

Abrasion group 2:

Group 2 tiles are already somewhat more robust: they can be used for rooms with light traffic. The surface resists minor scratching dirt and is therefore basically resistant enough to walk on with normal footwear. However, the inspection frequency should not be too high. Tiles of this abrasive group are therefore suitable for private living spaces, with the exception of heavily frequented and stressed areas, such as kitchens or stairs.

Abrasion group 3:

Class 3 tiles are most commonly found in private homes. They withstand medium loads well and are therefore suitable for most rooms with average foot traffic and dirt (e.g. living rooms, hallways, corridors). If the tiles are in principle approved for outdoor use, they can also be laid on balconies. Tiles of the abrasion group 3 can also be used in hotel rooms.

Abrasion group 4:

For rooms that are frequently entered with normal footwear or that are exposed to heavier loads, tiles in abrasion group 4 are recommended. they remain resistant to abrasion even under heavy loads and score points for their correspondingly long service life. Not only can they be used without restriction in the entire private living area, both inside and outside, but they are also resilient enough for public or commercial use. Tiles of this class are suitable for stairs, kitchens, terraces, offices, hotels, entrance areas etc.

Abrasion group 5:

Class 5 tiles are mainly used in commercial areas. They have maximum durability and abrasion resistance, which is why they are convincing even under the highest loads, foot traffic and dirt. Tiles of Abrasion Group 5 are mainly relevant for shops, restaurants and hotel lobbies, but also for garages, industrial halls, schools or railway stations. Such robust tiles are generally not necessary for private households.

For the sake of completeness, however, it should be mentioned again here that unglazed tiles can always be assigned to the highest abrasion class by default. Especially for highly frequented areas they are therefore sometimes the better choice. Particularly in the case of extreme stress, it is therefore advisable to rely on the material, which is by nature extremely abrasion-resistant.

Attention: Do not forget the anti-slip protection!

To ensure that tiles not only optimally withstand loads but also have the necessary slip resistance, attention should be paid to the anti-slip class of the tiles in addition to the abrasion group when selecting the tiles. This is particularly important for use in bathrooms, showers or outdoors. This is because the glaze of the tiles often tends to turn into a slide when wet or damp.

The classification of the slip resistance R9 to R13 shows the coefficient of static friction of glazed tiles and the angle of inclination up to which the surface can be walked on without risk. The suffix A, B or C also indicates how non-slip the tiles are in wet areas where bare feet are present (e.g. bathrooms, showers, swimming pools, etc.)

Extra tips against abrasion

The selection of the appropriate abrasive group already has a significant influence on the service life of glazed tiles. However, to ensure that the tiled floor remains free of visible signs of use for a longer period of time, the colour or brightness of the tiles should also be adapted to the use. For example, it is advisable not to use tiles that are too dark in areas subject to heavy traffic, as any changes in colour and gloss will be more noticeable on them. In addition, you should always use a chair pad under desks, for example.

Furthermore, it is of course important to clean the tiles regularly and properly. Due to the pressure and friction when walking on the floor, dirt and dust particles otherwise have a similar effect to sandpaper – and sooner or later this can have undesirable effects on the appearance of the tiles.

In areas with particularly heavy traffic, dirt-trapping mats or doormats can also be laid out to remove the coarsest dirt from street shoes and thus additionally protect the tiles.

Terrace, balcony or garden can be tastefully decorated with tiles in various styles according to individual preferences. However, the requirements are much higher outdoors than indoors. In this article you will find out which requirements tiles must fulfil in order to be able to exist permanently as floor coverings outdoors and what you should absolutely observe when laying them.

Possible applications of tiles: Exterior vs. interior

From small to large, from light to dark, from natural stone to wood look – tiles are available in the most diverse formats, colours and designs. Coupled with their advantageous properties in terms of comfort, durability and cleaning, this results in almost unlimited application possibilities. No wonder, then, that tiles are both popular and widespread as floor coverings not only indoors but also outdoors.

However, the conditions outside are completely different from those in enclosed living spaces. The ground is exposed to the weather all year round and the interplay of sun, rain, ice and snow demands a lot from the material. In order for the flooring to be able to withstand outdoor use for a long time, tiles must therefore be particularly robust and resistant to external influences and stress.

Which tiles are suitable for outdoor use?

In order to ensure that the tiles are able to withstand the daily stresses and strains on the terrace, balcony or garden, the following criteria should be taken into account when selecting the tiles:

Weather resistance and frost resistance

The most important criterion for outdoor tiles is that they are weatherproof. Thus, the material must not only be able to withstand the heat of direct sunlight in summer, but above all the cold and frost in winter.

Decisive for the frost resistance is the water absorption capacity. The rule is: the less, the more frost-resistant. If too much water penetrates into tiles and joints due to humidity or precipitation and expands in the cold, there is a risk of cracks, flaking or efflorescence.

In principle, a porous surface absorbs more water than a fine-pored one. For this reason, pure stoneware is generally not recommended for outdoor use due to its nature. Ceramic tiles made of stoneware or porcelain stoneware, but also natural stone (e.g. granite) or terracotta can very well be used outside, provided that they are approved for this purpose according to the information provided by the tile manufacturer.

The decisive factor for the degree of frost resistance is the classification, according to which the tiles are divided into the following five groups based on their water absorption capacity:

Group Ia: < 0,5 % water absorption capacity

Group Ib: < 3 % water absorption capacity

Group IIa: 3 to 6 % Water absorption capacity

Group IIb: 6 to 10 % water absorption capacity

Group III: > 10 % water absorption capacity

Group Ia and Ib tiles – i.e. up to a maximum water absorption capacity of 3 percent – are generally considered frost-proof. They are additionally marked with a blue ice crystal as a symbol and can be laid outdoors without hesitation. To be on the safe side, a tile with a water absorption capacity of less than 0.5 percent should be preferred in the best case.

In contrast, there is already a considerable risk of frost damage in groups IIa and IIb – and group III is not advisable for outdoor areas if the flooring is to survive the winter without damage.

Abrasion resistance

Another selection criterion for exterior tiles is abrasion resistance. It determines the stress the surface is suitable for without signs of wear and tear.

This is divided into 5 tiles abrasion groups:

Abrasion group 1: Very light duty

Abrasion group 2: Light duty

Abrasion group 3: Medium stress

Abrasion group 4: Heavy duty

Abrasion group 5: Very heavy duty

Basically nothing can go wrong with unglazed tiles in outdoor areas – they can always be assigned to the highest abrasion class. The hardness of the surface is comparable to that of diamonds, making them virtually indestructible even under extreme stress.

With glazed tiles, on the other hand, things look slightly different. Depending on the type and design of the glaze as well as the degree of wear and tear and soiling, visible signs of use are quite possible over time. Therefore, glazed tiles on the balcony should have at least abrasion class 3, for use on terraces or in the garden, abrasion class 4 is even more recommended.

Skid resistance

Last but not least, special attention should also be paid to slip resistance in the case of exterior tiles. This is because wet or damp tiles can quickly become slippery and cause nasty falls or injuries.

The slip resistance can be recognised by the skid resistance classes, into which tiles are divided depending on their static friction value:

R9: low coefficient of static friction, safe to step on at an angle of inclination of 6 – 10°

R10: normal coefficient of static friction, safe to step on at an angle of inclination of 11 – 19°

R11: increased coefficient of static friction, safe to step on at an angle of inclination of 20 – 27°

R12: high coefficient of static friction, safe to step on at an angle of inclination of 28 – 35

R13: very high coefficient of static friction, safe to step on at an angle of inclination of over 35

In outdoor areas, at least R10 should be selected, and R11 ensures even better slip resistance if there is a particular risk of slipping (e.g. on stairs). In areas that are also frequently walked on barefoot (e.g. in and around the pool or in the garden shower), attention should also be paid to the additional “B” or “C” marking for suitability in wet barefoot areas.

Unglazed tiles also offer a certain advantage in terms of slip resistance in outdoor areas. Thanks to their rough surface, they are naturally more slip-resistant. Even small tile formats can additionally increase the slip resistance due to the significantly larger joint proportion.

Garden, balcony and terrace: Choose the right tiles for the outdoor area

When choosing tiles for the terrace, balcony or garden, it is therefore advisable to always opt for the higher quality class. This may have an overall impact on the price, but the extra cost is worth it simply because of the longer life of the floor tiles.

Which exterior tiles are ultimately best depends primarily on personal preferences and the style of the house. Floor tiles for outside as well as for inside are available in the most diverse surfaces (e.g. unglazed, glazed, matt, silk matt, high gloss etc.), optics (e.g. wood optics, natural stone optics, marble optics etc.), formats (e.g. square, rectangular) and colours.

What should be taken into account when laying outdoors?

However, the decision for the right exterior tiles is only half the battle. Even the best flooring can be damaged – usually by water – if the tiles are not laid properly.

Therefore, outdoor installation should be carried out with great care, taking into account the following factors:

Prepare the substrate

The substrate for exterior tiles must be load-bearing, frost-resistant and completely even. Concrete slabs or a cement screed reinforced with construction steel mats on a compacted and sufficiently drained layer of gravel or crushed stone are most suitable.

A gradient of 2 per cent must be observed so that water can quickly drain away from the tiles to the outside. In order to protect the tiled floor from moisture even from below, the substructure should also be sealed (e.g. with bitumen coating or sealing slurry and double-layer PE foil). In addition, the surface should be carefully checked again for cracks, unevenness or any residue from removed flooring before installation and repaired if necessary.

The right laying material

When laying outdoors, only flexible tile mortars or adhesives should be used to reduce stresses on the floor surface and thus prevent cracks or fissures in the tiles.

Laying tiles correctly

When laying the tiles themselves, it is important to avoid cavities between the substrate and the tiles in order to prevent water inclusions. This is best achieved with the so-called buttering-floating process, in which the tile mortar or adhesive is applied both to the substrate and to the back of the laid tile. Alternatively, thin-bed installation can be used, in which the tiles are pressed in sections directly into the damp fluidised bed mortar or tile adhesive.

In the edge areas, it is essential to ensure that the necessary expansion joints are provided in order to give the floor the necessary scope for temperature-related expansion and thus avoid stresses. It is also important that the tile adhesive is allowed to harden (approx. 48 hours) before grouting is started.

Carefully grouting tiles

Leaky joints are often the Achilles’ heel of exterior tiles. They can easily allow moisture to penetrate and cause damage to the substructure, the tile mortar or the tiles themselves. Therefore, special care and precision is required when grouting in outdoor areas.

In order to be able to work as precisely as possible, the joint sealing compound should be applied to the gaps diagonally to the joint line with a rubber wiper. Excess grout can be removed with a sponge board after approx. 15 minutes of drying. In the last step, the expansion joints and other transitions can then be sealed with silicone.

ATTENTION: The surface can only be walked on and loaded when the tile mortar or adhesive has completely hardened. This phase can take different lengths of time depending on the product, so it is essential to follow the manufacturer’s instructions. During the drying phase, excessive humidity and direct sunlight should be avoided.

Although tiles are generally considered to be virtually waterproof, they do not protect against water damage. And it is not only unpleasant, but can also be expensive and even dangerous. In this article you will learn what causes moisture under tiles, how to find a wet spot and how best to eliminate the problem.

Risk factor moisture

In principle, moisture in buildings is not a bad thing, in fact it is important. In the air, it contributes to a pleasant indoor climate and almost all building materials and materials only retain their stability permanently through the regular absorption of water or water vapour. However, only as long as the humidity remains within limits.

Too much moisture under tiles can sooner or later lead to water damage – and thus inevitably to a rat tail of negative consequences. These affect not so much the tile itself as the substrate on which they are laid. So musty smelling rooms and dark spots or salt efflorescence on the wall are the lesser evil. It is far more serious if the damage already affects the entire floor structure or the entire masonry, and if mould which is a health hazard has already formed on it. Because in these cases a complex and expensive complete renovation is usually no longer to be prevented.

Possible causes for water damage under tiles

Basically, water damage under tiles can occur in two ways:

  1. Because moisture is trapped under the tile covering, or
  2. Because water comes in from above.

For the former, improper tiling is usually responsible. For example, if tiles are laid on a floor structure that is not sufficiently dry or if there is so-called subsequent moisture from the substrate after laying. In these cases, moisture remains permanently under the tiles and can cause damage to the entire floor structure. For this reason, especially with freshly laid screed, it is important to check the readiness for laying by determining the residual moisture before starting to lay the tiles. Particularly in the case of large-format tiles with a low proportion of joints, it also sometimes happens that the moisture cannot escape sufficiently from the jointing mortar or tile adhesive and thus also remains under the covering.

The second cause of water damage is that wetness only gets over the surface and under the tiles afterwards. Whether it is due to acute exposure to water, such as flooding, burst pipes or the leaking washing machine, or due to regular exposure of the tiles to moisture, such as the steam in the shower or bathroom. However, the moisture does not penetrate through the tile itself, as the material hardly absorbs any water, but through the joints. Regardless of which filling material is used, joints are always water-permeable – even joints sealed with silicone can become brittle or perforated over time and thus lose their seal.

So the crux of the matter is: under tiles, water damage usually goes unnoticed for a long time. The coating probably covers the affected area so that the water can spread unhindered. And even if damage is then already apparent, the actual extent is usually still hidden under the tiles.

This makes it all the more important to start looking for the cause at the slightest suspicion or at the latest at the first signs and to obtain certainty by determining the moisture content under the tiles.

Measuring moisture: How it works

There are various possibilities for measuring moisture under tiles, which differ in effort and significance:

Direct procedures

In direct methods, such as the calcium carbide (CM) method known for determining the residual moisture of screeds, a sample is taken from the building material, crushed and mixed with calcium carbide in a pressure bottle. Based on the chemical reaction, the moisture content can then be determined using a manometer. This method is considered to be particularly reliable – and incidentally, it is also the only one recognised by the courts – but it is also the most complex and can only be carried out by a specialist.

Indirect methods

Indirect moisture analysis using moisture analyzers, on the other hand, is much simpler and therefore basically also practicable for private use. Numerous tile manufacturers offer a wide variety of models, most of which are already available at relatively low prices. Depending on the type and design, these devices can usually be used to measure floor or wall moisture even through tiles or other surfaces.

In principle, two variants are common for this:

Capacitive measurement

With the capacitive method, the moisture meter generates an electrical stray field in the sensor head, via whose permeability the moisture content at the respective location is determined at a depth of approx. 3 cm. The advantage of this method is that it is completely non-destructive and can be repeated as often as desired. The disadvantage is the relatively small measuring depth, which means that the results may not be reliable enough in the event of deeper water damage. In addition, a certain amount of expertise is advantageous for the correct interpretation of the measured values, as these can be influenced by salts or metals in the building materials.

Resistance measurement

In electronic measurement according to the resistance principle, current is conducted via electrodes into the presumably moist area. The conductivity of the material then provides information about the moisture it contains. The higher the resistance, the lower the measurement result and thus the moisture content. The advantages and disadvantages of such a moisture meter: the wall or floor must be drilled at the affected area in order to be able to insert the electrodes, but it is also possible to detect deeper water damage. Alternatively, however, it is usually possible to measure over joints.

Nevertheless, caution is generally advised when searching for water damage on your own. Since the results are determined differently for each measuring instrument and are displayed according to manufacturer-dependent scales, there are no general standard values. In order to obtain really reliable information about the moisture content, it is therefore always advisable to consult a professional.

Water damage – what now?

If water damage is detected, there is definitely a need for action. Whether it is sufficient to dry the affected areas sufficiently and eliminate the cause (e.g. renew leaking silicone joints in the bathroom) or whether major renovations are already necessary, however, again only an expert can judge. If the wrong measures are taken, the damage can sometimes be even worse.

Tiles and underfloor heating have one thing in common: both offer building owners numerous advantages in terms of living comfort and therefore form an ideal combination. Nevertheless, the topic repeatedly raises uncertainties and questions in the run-up to the event. You will find the most important answers in this article.

Which floor covering is best suited for underfloor heating?

Whether tiles or stone, parquet or laminate, vinyl or carpet – anyone who wants cosy warmth without radiators can in principle draw on the full range. In principle, any floor covering can be laid on underfloor heating.

The difference, however, is how quickly the heat from the underfloor heating system is transferred to the floor, or what flow temperature is necessary (and possible) to control the room temperature as desired. In other words, the different materials differ in their thermal conductivity. This in turn has an impact on energy efficiency and thus ultimately on heating costs.

This is precisely why tiles are the best choice for underfloor heating. Due to their dense surface, they score points with a very high thermal conductivity between 2.3 and 2.8, which is about 5 times higher than, for example, underfloor heating under hardwood flooring or underfloor heating under vinyl flooring. In addition, the heat is stored in the tiles, which means that the floor not only heats up quickly, but also stays warm for a long time – thus saving additional energy.

Can all tiles be used in combination with underfloor heating?

There are essentially no restrictions when using tiles on underfloor heating. Both natural stone and stoneware and porcelain stoneware are equally suitable for underfloor heating. To achieve the most efficient heating result, tiles with a maximum thickness of 20 mm are recommended. Thicker coverings are also possible, but the heating time may increase slightly.

Regardless of the heating system, when selecting the floor tiles, attention should also be paid to the abrasion group of the tiles and the anti-slip class of the tiles. This ensures that the floor meets the requirements of the respective area of application in the best possible way.

What surface temperature can tiles for underfloor heating withstand?

A great advantage of tiles is that they can withstand even high temperatures without damage. In contrast to many other floor coverings, they can therefore be heated to a surface temperature of 29°C and more without any concerns. This results not least in the high heat output of up to 200W/m2 with simultaneously low energy consumption.

Tiles on tiles & floor heating – is that possible?

Particularly in the case of renovations, the question often arises as to whether the new tiles can be laid on top of the existing tile covering. The answer to this is quite clear: Yes, on underfloor heating this is no problem. The combination of tile on tile – underfloor heating works perfectly and without affecting the heating result: Due to the extremely high thermal conductivity of the tiles and the correct tile adhesive as an additional heat conductor, the heat of the underfloor heating is transferred from layer to layer without loss.

Only condition: The old flooring must be perfectly laid and intact and in the spatial conditions the higher floor construction must not cause any problems (e.g. stripes of doors etc.).

What should be observed when laying tiles on underfloor heating?

Although tiles and underfloor heating harmonise perfectly, there are a number of points to consider before and during installation to prevent any difficulties from the outset.

Type of underfloor heating

There are basically two options for underfloor heating: They can be operated either with water or with electricity to generate heat. In principle, both water-guided and electric underfloor heating can be installed under tiles. Which heating system is most suitable depends rather on the respective application.

Warm water underfloor heating systems work via plastic or copper pipes, which are inserted into the screed as a wet or dry system and through which heated water circulates. Because the installation effort is relatively large and a certain installation height is also necessary, hot water underfloor heating systems are primarily used in new buildings.

In contrast, with electric underfloor heating systems thin heating mats ensure the correct room temperature. These can also be laid on the screed at a later date with relatively little effort and require a lower installation height. They are therefore also suitable for the renovation of existing buildings or can be retrofitted as a supplementary heating system in rooms with high heat loss (e.g. conservatories).

Condition of the substrate

An optimal substrate is the basic prerequisite for a durable and flawless tiled floor. Therefore, tiles should not only be laid on a substrate that is as smooth as possible, but especially on a completely dry substrate. Because too much moisture under the tiles can otherwise sometimes cause the tiles to come off or other damage later.

Particularly when laying on newly erected and wet laid heating screeds, care must therefore be taken to ensure that they are ready for laying. Normally, a screed needs about 4 weeks to harden completely – in the meantime, however, special quick binders are increasingly used to accelerate the process. In general, it is advisable to heat the screed in a controlled and gradual manner using underfloor heating. On the one hand, the drying phase can be shortened and, on the other hand, both the heating and the screed can be checked for function and condition.

The screed is finally ready for laying the tiles when the residual moisture determined by means of a suitable measuring method (e.g. CM method) has fallen below a certain limit. As a guideline, a maximum of 2 % for cement screeds and a maximum of 0.3 % for calcium sulphate screeds are to be taken into account, whereby the laying instructions of the manufacturer are to be observed for the exact values.

Protection against moisture

In principle, tiles can be laid directly on the screed. However, in order to protect the substrate from penetrating moisture from the tile adhesive, it is recommended to apply a sealing primer or tile primer before laying. Otherwise, there is a risk that the screed will soften and the flooring will no longer adhere properly.

Suitable tile adhesive and tile mortar

Although underfloor heating generally heats tiles very evenly and constantly, temperature fluctuations still occur. This leads to slight expansion of the material and corresponding stresses on the surface. To compensate for these movements – and thus prevent stress-induced cracks in the tiles – highly flexible and temperature-resistant materials should therefore be used as tile adhesives or tile mortars. In some cases, a decoupling mat can also be laid under the tiles.

During installation, care should also be taken to ensure that these are applied over as much of the surface as possible. This allows the tile and adhesive to bond better, which is particularly advantageous in the case of surface tension. And besides, the heat transfer is additionally optimized.

Expansion joints

A no less important aspect in connection with the temperature-related expansion of the materials is the interaction expansion joint – tiles – underfloor heating.

Expansion joints should be taken into account, especially in edge areas, and should allow for a minimum of 5 mm room for movement. In addition, it is essential to create additional expansion joints in those places where the screed also has them. Otherwise, the tile and substrate may expand differently, which may lead to cracks or fractures.

When can the underfloor heating be put into operation after tiling?

A freshly tiled and grouted floor must not be heated up immediately. This could cause the adhesive and joint sealant to dry too quickly and become brittle. The general recommendation is to wait about 28 days until the underfloor heating is activated. The temperature should then be increased continuously in 5-degree steps over a period of several days until the desired flow temperature is reached.

The aim of tiling is undoubtedly a perfectly flat surface and a uniform joint pattern. A task that is often not so easy. With a levelling system, however, it is relatively easy to manage. In this article you will learn how the user-friendly tile laying aid works, the advantages of laying tiles with a levelling system and the best way to proceed.

The challenge: Laying tiles flat

The laying of tiles is undoubtedly associated with many a challenge.

One of them – if not the largest – is to position tile after tile at exactly the same height and at exactly the same distance from each other.

Even the slightest unevenness in the floor or the slightest irregularity in the distribution of the tile adhesive inevitably leads to a difference in level between the individual tiles. And this can literally become an obstacle: If a tile is even slightly higher than the one next to it, there will be protruding edges. These so-called overteeth can quickly turn out to be an annoying tripping hazard, sometimes even causing injuries. Apart from that, such differences in height naturally do not look very nice and thus impair the overall visual appearance of the tiles.

Laying tiles flat is therefore no child’s play from the outset. The trend towards ever larger and thinner tiles is doing the rest. Whereas in the past, the tiles laid were mainly small format, usually square, the range of products has been continuously expanded in recent years thanks to sophisticated production processes and improved materials. Tiles with 60 cm side length have become standard in the repertoire of the tile manufacturers and also tiles in plank format with up to 3 m length are no longer a rarity.

Although modern tiles make completely new dimensions in interior design possible, XXL tiles sometimes have their price when they are laid.

With increasing size, tiles are by nature no longer completely flat. The reason for this is that the material bulges slightly during the firing process. Although these “bowls” are usually hardly visible to the naked eye at first, marginal differences in the height of the tiles become all the more noticeable during installation at the latest. Since the height offset usually extends over the entire tile, the larger the tiles, the longer the edges will logically be.

That is why even experienced professionals have their troubles with overteeth on large format tiles again and again. They can only be avoided or repaired – if at all – with a great deal of time and effort. Just how difficult it really is to lay tiles flat is shown by the fact that even in the binding set of rules of the DIN standard, height differences in tiles are permitted up to a tolerance limit of 1.5 mm.

The solution: levelling systems

However, this does not mean that a flawlessly even tiled surface is no longer possible in principle. On the contrary. Fortunately, as is so often the case, it did not take long to find the right solution to this problem. And in this case the solution is called a levelling system.

With the practical tile laying aid, height differences between two tiles can be compensated for without much effort and at the same time a uniform joint spacing can be ensured. So anyone who uses a tile levelling system during installation kills two birds with one stone, so to speak: considerably less work and a visibly better result – guaranteed without unsightly edges and dangerous tripping hazards. It is therefore not surprising that levelling systems not only make it much easier for do-it-yourselfers to lay tiles, but are also becoming increasingly popular with professional tilers.

What levelling systems are available and how do they work?

Levelling systems are available in two different versions: either as a pull system or as a push system. The underlying principle is the same for both categories, the difference lies in the concrete way in which the tiles are ultimately levelled.

With each system, plastic plates are first placed under the tiles – ideally at a distance of 5 to 7 cm from the corners. On each plate there is a flap that protrudes a few centimetres above the tiles. On the one hand, these brackets always guarantee the same joint spacing to the next tile (depending on the product, joint widths between 2 mm and 4 mm are possible) and on the other hand serve as a fastening element for the actual levelling system. Depending on which system is used, the further procedure is slightly different.

Printing Systems

If it is a tile levelling system with pressure, the flap is usually in the form of an arch. As soon as two adjacent tiles are laid, wedges are inserted into the openings of these arched tabs using special pliers. The interaction of the wedges and plates creates pressure on the tiles. With the effect that the higher tile is pressed down until it is exactly plane-parallel with the lower tile.

Train Systems

In comparison, tension levelling systems work exactly the other way round: here the lugs of the plates serve as threaded lugs onto which tension hoods are screwed after the laying of two adjacent tiles. As the name suggests, these hoods create draft. As a result, the lower tile is pulled up until it reaches exactly the same level as the higher tile.

After the tiles have been levelled and the adhesive has dried completely, wedges or pulling hoods of the levelling systems are removed again and the protruding tabs are broken off at the predetermined breaking point provided for this purpose. That part of the tab that serves as a spacer remains in the joint of the tile and thus reliably prevents the tiles from slipping. The plastic plates also remain permanently under the tiles, but are of course – just like the lugs – no longer visible after grouting the tiles with grout.

What advantages do levelling systems (still) offer?

Regardless of which tile levelling system is used, in the end the result is the same there as there: the tiles form an absolutely flat plane with exactly even joint spacing. This prospect alone of achieving the desired perfect result makes it worthwhile to lay tiles with a levelling system. For those who are still sceptical whether levelling systems are actually absolutely necessary for this purpose, or whether, as used to be the case, spirit levels and joint crosses might be sufficient, the following overview of the advantages of a levelling system can make the final decision easier.

Easy handling

In practical use, a levelling system is as simple as it is effective. The procedure is basically almost self-explanatory and can be integrated into the laying of the tiles in just a few steps. To work with the levelling system, no special knowledge or experience is required. Even inexperienced hobby craftsmen can quickly get to grips with the levelling system and ultimately benefit from professionally laid tiles.

Universal application possibilities

A tile levelling system is extremely versatile in its application – there are practically no restrictions. Neither with regard to the material and thickness of the tiles, nor with regard to the way they are laid or the area of application. Ceramic tiles and slabs and porcelain stoneware with a thickness between 3 and 12 mm can be laid flat, as can natural stone tiles, which are sometimes up to 25 mm thick. This is regardless of whether the tiles are to be laid on the wall or on the floor, indoors or outdoors, and in half, three-quarter or cross-bonding.

Ideal for large format tiles

Admittedly, a levelling system is actually not absolutely necessary for small format tiles. Overteeth are to be found there anyway relatively rarely and/or can be concealed in the case of the case also relatively well. In addition, the demand for brackets and pulling hoods is above average, which means that the levelling system probably causes more effort than it brings benefits. However, small tiles are hardly laid nowadays. Which in turn means that for most tile projects the much more demanding, large format tiles are used – and levelling systems are highly recommended.

Low price, high savings

A tile levelling system is relatively cheap to purchase. Usually the different systems are available as a set with all necessary components. A big advantage is that the wedges and pulling hoods contained in the kit can be reused several times. Only the plastic plates including the tabs are consumables, as they remain permanently between or under the tiles.

The low price for the levelling system is at the same time offset by high savings. Namely time, effort and of course trouble. At first glance, it may appear that laying with a levelling system is more complex and time-consuming than without. But in the end, despite the additional work steps, a quick installation is guaranteed. Firstly, attaching the plates, wedges, pull straps or pull hoods for the respective system is practically automatic after just a few tiles. Secondly, tiles of unequal height do not have to be removed and re-laid as is necessary without a levelling system. And thirdly, the levelling system allows easy readjustment as long as the tile adhesive has not yet hardened – for example, if an unevenness between the tiles has been overlooked.

What to look for when buying a levelling system?

Once the decision has been made to install the flooring with a tile levelling system, the next step is to find the optimum product. For this to succeed, two essential aspects should be taken into account:

The right system for the tiles used

The crucial question is first of all: tension or compression. Basically one levelling system is not better or worse than the other. However, the key to the scales is which tiles are actually laid. If it concerns common sizes or rectangular formats (e.g. 60 x 30 cm), both push and pull systems are equally suitable. In this case it is much more important which levelling system is more appealing to the do-it-yourselfer. For particularly large tiles, however, it is recommended that printing systems are preferred. This is because with pulling systems there is sometimes the danger of lifting the large tiles too far out of the usually quite thin mortar bed or of tearing off the pulling straps during levelling.

The best set for the respective requirements

For each system there are numerous different product variants from different manufacturers. Well-known brands, such as Karl Dahm, Hufa, Knauf or Kaufmann, generally guarantee the high quality of the systems and therefore generally offer more security than no-name products. Regardless of the brand, levelling systems are usually available as a complete set in tile specialist shops or DIY stores as well as in various online shops or on Amazon.

In order to be able to search specifically for suitable products and compare them with each other, a few essential considerations should of course be made in advance. This primarily concerns the material requirements – i.e. how many pieces of pulling straps, wedges or pulling hoods are required for the respective tile format and whether any other accessories (e.g. pliers, rubber mallet, adhesive, etc.) are advantageous for laying with the tile levelling system.

The planned installation method and the desired joint width also play a role. This is because it determines what the lug should look like in the optimum case for the respective tile levelling system. In addition to the standard basic brackets, there are often special X or T brackets for laying in cross or three-quarter joints. In addition, the tabs are available in different widths to create joints between 2 mm and 4 mm.

TIPP: Wider joints can be easily achieved with joint crosses in addition to the tile levelling system.

Which of the numerous set offers ultimately offers the best price-performance ratio depends on how exactly the scope of delivery meets the needs and requirements.

Laying with tile levelling system in 3 steps

Finally, we would like to use our step-by-step instructions to show you once again how easy, quick and uncomplicated it is to achieve a perfect result when laying your tiles with a levelling system:

Before laying: Prepare the subfloor

Whether with or without a levelling system – before you can even start tiling, you need a perfectly prepared substrate. This means that the soil must be load-bearing, clean, dry and level. Depending on the adhesive, a adhesive primer should also be applied to the tiles. In case of cracks in the substrate or for bridging, a decoupling mat for tiles should be used. Please note that although levelling systems are ideal for levelling differences in height between tiles, they are not suitable for levelling uneven surfaces. It is best to use self-levelling putty for this purpose.

Step 1: Laying tiles

Once you have completed the preparations, you can start laying the tiles. First apply the tile adhesive evenly to the floor with a suitable notched trowel and lay the first tile on top.

Attention: Especially for larger formats, it is recommended to use the buttering-floating method. This means that you also cover the back of the tile with a layer of adhesive.

Then take two (or more for large tiles) plastic plates with flaps and place them evenly along the edge of the tile underneath the tile. Remember that the distance to the corners should be about 5 to 7 cm. Then take the next tile and place it next to the first one so that the plate is firmly fixed under both tiles and the tab sticks out of the joint. Repeat this procedure until the first row of tiles has been laid.

Step 2: Levelling (using the example of a train system)

Now take the pulling hoods and screw them onto each threaded lug. Turn carefully until you encounter resistance – you will then be at the level of the first tiles. To bring two adjacent tiles to the same height, continue turning until they are exactly plane-parallel.

carefulness: Stop the levelling process immediately after the tiles have reached a level. If you continue to turn, there is a high risk that the pulling cover will break off. Once all tiles are levelled, allow the adhesive to cure according to the manufacturer’s instructions.

Step 3: Remove levelling system

When the tile adhesive is completely dry, you can remove the levelling elements. First unscrew the pulling hoods (you can collect these and reuse them for the next tiling project) and then break off the remaining tabs at their predetermined breaking point. This can be done very easily with your hand or foot, but of course you can also use a suitable tool (e.g. a rubber mallet) instead. Finally, simply sweep up the leftovers and dispose of them in the trash.

Your perfectly even tiled surface is already finished and can be grouted as usual! By the way: The fixing elements of the levelling system secure the tiles so reliably against slipping that you can walk on them carefully even before grouting.

They have already become the standard for professional tilers – and the use of decoupling mats definitely has advantages for do-it-yourselfers too. Because by decoupling from the subfloor, consequential damage during tile installation can be reliably prevented. In this article you can read about when a decoupling mat makes sense, what functions it fulfils and how best to lay tiles decoupled.

Why do you need decoupling mats at all?

Tiles are extremely popular as floor coverings: they score points with their attractive appearance, are robust and hard-wearing – and are in principle suitable for laying on almost any surface. In principle, it is quite common to bond tiles directly to the screed, but it is often advisable to lay them separately. The reason for this is as simple as it is serious:

As building materials expand and contract again with temperature fluctuations or moisture, movements in the soil inevitably occur. But the crux of the matter is that the elongation behaviour is different for every material. Thus, tiles usually react differently to changing conditions than the underlying floor. If there is a rigid connection to the ground, this can quickly have unpleasant consequences. Although the movements are usually only fractions of a millimetre, the resulting stresses are sufficient to cause cracks or fissures in the tiles. Such damage can be prevented with decoupling mats. This is because they provide the necessary scope for the materials to expand independently in all directions.

What is a decoupling mat?

As the name suggests, a decoupling mat decouples the covering from the floor. This means that the mat forms an additional flexible separating layer between tiles and substrate. Since there is no longer a direct connection, movements, tensions or vibrations are no longer transmitted from the substrate to the tiles. The decoupling mat absorbs them completely or at least minimizes them so that no cracks can develop.

Where should a tile decoupling mat be used?

To be on the safe side, there is no harm in principle in laying tiles decoupled. However, in some cases it is particularly important. First and foremost, this concerns the laying of tiles on critical or vibrating surfaces. In other words, wherever the risk of stress-related damage is particularly high or where unevenness and cracks in the substrate have to be compensated.

Freshly laid screed, for example, tends to crack when drying, which can be bridged by a decoupling mat. Decoupling mats are also obligatory when laying tiles on an existing wooden floor. This is because the latter generally reacts to external influences, such as temperature or humidity, with stronger expansion behaviour.

But even if large areas and/or large-format tiles are bonded, above-average stresses can occur overall. The same applies to spot or weather-related temperature fluctuations when tiles are laid, for example, on underfloor heating systems or in outdoor areas. In addition, decoupling mats are also highly recommended for particularly high loads (e.g. in garages) in order to provide the necessary protection against cracks or breakage.

In addition, a decoupling mat improves the adhesion of the tiles, making it possible to lay them on poorly adhering subfloors. For this reason, for example, decoupled installation should also be preferred on floors with existing layers of adhesive, varnish or paint.

ACHTUNG: However, with particularly flexible substrates (e.g. if the rafter spacing in the substructure is too wide), decoupling mats sometimes reach their limits. In this case, it is recommended to first lay plasterboard or OSB boards and only then to attach the decoupling matting.

What types of decoupling mats are available?

Various manufacturers offer decoupling mats in various designs and materials. Most common are products made of plastic, rigid foam or textile fibres, which are usually available as yard ware on rolls in specialist tile shops or DIY stores.

What all commercially available decoupling mats have in principle in common is their multi-layer structure. While the flexible core of the mat ensures the described equalization of tensions and movements, the mostly nubbed outer layer is used for fixing to the substrate on one side and the tile covering on the other side. In addition, ventilation ducts are often installed on the underside, allowing moisture to escape from the respective substrate even after the tiles have been laid.

In principle, modern decoupling systems are therefore suitable for almost any difficult substrate, such as concrete, mixed subfloors, wooden floorboards, chipboard, cement or dry screed, old tiles and many more. Which decoupling mat is best in a specific case, however, depends on the respective area of application and the associated requirements. This is because in addition to the actual function of decoupling, most mats also have other advantages.

Textile mats in particular, such as a PCI decoupling mat, are characterised by improved footfall sound insulation. While other systems, such as Schlüter Ditra decoupling mats, are universally applicable at all, as they combine multifunctional properties in one product with decoupling, sealing, vapour pressure compensation and drainage.

How are decoupling mats installed?

Laying decoupling mats is easier than you might think, but there are a few things to consider.

In principle, decoupling mats can either be glued over the entire surface or laid as a floating installation, whereby the former is more common in practice. However, the method to be used for the respective product always depends on the manufacturer’s recommendations.

Nevertheless, the procedure for both installation techniques is almost identical and essentially consists of the following steps:

Step 1: Prepare the substrate

Regardless of whether the decoupling mat is to be laid floating or glued, the subfloor must be clean, level and load-bearing. For highly absorbent substrates, a primer or a tile primer may also be useful.

Step 2: Measuring and cutting the mats

Before laying, the spatial conditions are measured and the mats are cut to size accordingly. In order to avoid unnecessary waste, special care should be taken – even a laying plan can sometimes be helpful. To avoid sound bridges, insulation strips should also be used in the edge areas.

Step 3: Attach decoupling mat

With floating installation, the decoupling mat is only loosely applied to the substrate. For full-surface bonding, the mat is fixed with highly flexible tile adhesive (marking C2). It should be noted that the adhesive hardens very quickly. Therefore, only as much should be applied as can be covered with the decoupling mat within a few minutes.

Step 4: Sealing the joints

Although decoupling mats are waterproof on the surface, water can still get into the ground at the joints. Therefore, an appropriate sealing of the latter is necessary. Usually sealing tapes are used to prevent the penetration of moisture under the tiles.

Step 5: Laying tiles

The decoupled subfloor is then ready, on which the tiles can be laid in the usual way using flexible tile adhesive.

What does decoupling cost?

Finally, a few words about the costs of decoupling mats:

Basically, of course, the material requirement is decisive due to the number of square meters of the area to be decoupled. In the end, however, the materials used as well as the quality and functionality of the selected mat, but also the manufacturer, are decisive for the actual price. Standard mats are available for just a few euros per square metre, while particularly high-quality products are happy to make a multiple of that. On average, a realistic calculation can be made at around 10 euros per square metre, plus the cost of the flexible tile adhesive. All in all, decoupling mats are therefore not exactly cheap. With regard to a durable and above all damage-free tiled floor, the investment is definitely worthwhile.

Levelling compound paves the way for a beautiful new floor. Literally in the truest sense of the word. This is because it serves to level out unevenness in the substrate simply and reliably. Why this is so important, especially when laying on tiles, what different levelling compounds are available and how to proceed best when levelling, we will tell you in this article.

Levelling tiles – what for?

Even if tiles are considered to be extremely durable, sooner or later the moment will probably come when a new covering is needed. Be it because the floor (or even the wall) has become unsightly over the course of time, shows signs of damage or because the tiles simply no longer please.

One option is then to remove the tiles. However, it is far less complicated to simply install the new covering over the old tiles. This is possible in any case, because in principle almost all coverings can be laid on tiles. However, what is generally true for laying floors is especially true in this case: For a flawless result, you need an optimally prepared substrate. This means that the surface must not only be clean, dry and load-bearing, but also, and above all, level. At this point at the latest, the balancing mass comes into play. This is because it ensures the necessary level surface.

With tiles, unevenness is usually pre-programmed by the deeper lying joints alone. In addition, there are sometimes striking structures or patterns on the tiles that can become apparent when laying thinner, flexible coverings (e.g. carpet, PVC, vinyl, etc.). Moreover, the uneven areas increase the risk of cracks or other damage – even supposedly strong materials such as parquet, laminate or a new layer of tiles are not immune to this. Equalizing compound can eliminate all these potential problems in just one step.

What purpose does equalizing mass (still) serve?

But of course, levelling compounds are not only used for tiles. They are generally used wherever there is a need to level out unevenness. This ranges from spot repairs in damaged areas to the levelling of an entire surface – regardless of whether it is indoors or outdoors, whether it is a wall or a floor, and regardless of the material of the substrate. With a possible layer thickness of 30 mm or even more, it is also possible to use levelling compound to increase the floor over the entire surface – for example, to remove barriers or level differences.

What types of balancing mass are there?

In the trade, there is a suitable balancing mass for every application. Depending on the manufacturer and product, they can also be found under designations such as putty, levelling compound or flow filler. Common to all products is that they are dry powders that are mixed with water and applied to the substrate as a liquid mass. There are, however, certain differences with regard to the ingredients and thus the possible applications.

Basically, levelling compounds consist of either cement or gypsum. In addition, certain additives can be added to the material to improve the properties of the levelling compound (e.g. flexibility, faster drying, higher layer thickness, etc.).

Which balancing mass is suitable for what?

Which product is most suitable depends both on the type of use and on the substrate in question. For concrete, cement screeds and most rigid coverings (e.g. tiles), conventional levelling compound is usually sufficient. Even smaller unevenness can usually be repaired without problems. It should be noted, however, that gypsum-containing compounds are not recommended for wet areas (e.g. in showers or bathrooms) or only with additional sealing.

In contrast, some substrates require a little more for the appropriate levelling compound. Wooden floors, dry and heated screeds as well as mastic asphalt, for example, should only be levelled with levelling compound which is flexible due to special additives. If the levelling compound is used under tiles in outdoor areas, it should again be able to level out larger unevenness and also be naturally frost-proof.

In order to be able to select the right product, however, the manufacturer’s specifications of the respective product are decisive in the end in every case. Therefore, these should be strictly observed before every purchase. On the one hand, the packaging contains all the necessary information for the possible areas of application, and on the other hand, precise details about the minimum and maximum height of the compensation mass. How thick the mass must or can be applied is also a decisive criterion. In the interior, for example, it makes a significant difference whether 3 or 20 mm is required for an optimum result if, for example, doors would block due to an excessive compensating mass. While at equalizing mass outside, as mentioned above, higher layers of material should be possible, in order to straighten also larger unevenness.

Apply levelling compound on tiles correctly: Proceed as follows step by step

In order to ensure that in the end the joy of the new covering on the old tiles lasts as long as possible, the greatest care is required. This starts with the preparation of the substrate, continues with the proper application of the material and ends with the correct application of the levelling compound on tiles. The following steps are necessary for this:

1.check tiles

In order to ensure the necessary support for the new floor covering, a solid base is required. Therefore, the first step is to check the adhesion of the tiles to the substrate. This is best done by tapping with a rubber mallet. If a tile sounds hollow, it is too loose and needs to be re-glued or removed. Damaged joints should also be scraped out if possible. Any gaps that may arise can already be filled with filler at this point.

2. clean the surface

In the next step, the surface must be thoroughly cleaned. An alkaline cleaner not only removes soiling, but also reliably dissolves greasy deposits and care product residues. In addition, the surface can be roughened with a diamond grinder – but this is usually not absolutely necessary.

3. apply primer

In order for the levelling compound to adhere better to the tiles, a primer or adhesion primer for tiles is strongly recommended. This is simply distributed evenly on the tiles with a roller. It is important that it is a primer for non-absorbent surfaces. Adhesion primers made of expoxy resin or quartz sand are the best choice. It must also be ensured that the primer is completely dry before the levelling compound is applied.

4. mix the levelling compound

When the primer is dry, the levelling compound can be mixed. The exact mixing ratio of powder and water can be found in the description of the respective product and must be strictly observed. Otherwise the mass becomes too liquid, which can affect the quality of the result. It is best to mix with a whisk in one or better several sufficiently large buckets – and continue mixing until the mixture is lump-free and homogeneous.

5. apply insulation strips

In order to avoid sound bridges, insulation strips should be attached to the wall. These ensure that the levelling compound does not flow into the edge joints and that impact sound or other noises can therefore be transmitted directly from the floor to the wall. The insulation strips also help to prevent cracks in the levelling compound.

6. apply levelling compound on tiles

After all these preparations, the equalizing mass is finally applied. As most products are self-balancing, they can be poured directly from the bucket and only need to be slightly directed in the right direction with a spatula or roller. Finally, the soil must be aerated with a spiked roller – or shoes with nail soles.

7. allow the levelling compound to dry

The levelling compound can be walked on after approx. 3 to 4 hours. However, before the new floor covering can be laid, the surface must be completely dry. As a rule, this is the case after about 24 hours, whereby the manufacturer’s specifications are also decisive here.

The right tile adhesive is one of the most important criteria for an optimal result when tiling. Unfortunately, it is not always easy to find it among the countless products. That’s why good advice is needed – and that’s exactly what this article is supposed to offer you.

What is the important thing with tile adhesive?

Laying tiles is not exactly the easiest thing to do. In order to achieve the desired quality, you need not only manual skill and the utmost care in preparation and execution, but above all the right material. And this applies not only to the tile itself, but also to the tile adhesive.

But this is also the key point that challenges even experienced craftsmen when making purchases. At first glance, tile adhesives appear to be almost indistinguishable. And also their actual function, i.e. to glue tiles, is basically fulfilled by all of them. However, you should not choose a product arbitrarily. Ultimately, the decisive factor is for which tiles, on which substrates and in which application areas the respective adhesive is suitable. And when it comes to these factors, not every product is the same.

What types of tile adhesives are available?

Basically, a distinction is made between cement-based and non-cement-based tile adhesives, although within these two categories there are different variants:

Cementitious tile adhesives

Cement adhesives are the most commonly used today for laying tiles. Although the term “adhesive” is actually not quite accurate in this case. In truth, these are not so much tile adhesives in the literal sense of the word as mortars.

The products usually consist of a cement-sand base and various additives and are available as dry mixtures in bags or buckets. To become ready for use, the powder only needs to be mixed with water to form a lump-free mortar mass. The adhesive effect results from hydraulic curing. This means that by adding water, the cement becomes solid and thus ensures the necessary adhesion of the tile.

But beware: This setting process is relatively fast, which is why it is necessary to process it as quickly as possible. You should therefore not mix too much tile adhesive at once, otherwise it will not be possible to apply it. Completely dry and thus resilient, the adhesive is usually after about 24 hours, the product contains special accelerators, the time span is even shorter.

Cement adhesives are very useful for laying on the wall as well as on the floor. In principle, they can be used on all rigid, absorbent surfaces, such as concrete, screed or plaster. In addition, they are water-resistant and frost-proof and are therefore also suitable for tiles in outdoor areas without further ado.

Flexible adhesive

The so-called flex adhesives offer even more application possibilities indoors and outdoors. They also belong to the cement-based tile adhesives, but become a real all-round genius thanks to special plastic additives.

Firstly, the plastic component allows the material to cure more flexibly. This enables flex adhesive to better compensate for vibrations, tensions and movements in the substrate and thus prevents cracks or chipping in the tile. This is particularly advantageous when laying tiles on subfloors such as dry screeds, fibre cement, plasterboard and wooden floors, but also for tiles on underfloor heating systems.

Secondly, the plastic provides a significantly higher adhesive strength than is the case with conventional cement adhesives. This means that flexible mortar not only ensures a secure hold on difficult or particularly smooth surfaces (e.g. tiles on tiles), but also when laying tiles with a very dense or glassy surface, such as porcelain stoneware or mosaics.

But all these advantageous properties have their price, of course. Flex adhesives are generally much more expensive than standard tile adhesives.

Natural stone adhesive

Since conventional cement adhesive is not suitable for natural stone, there are special natural stone adhesives for this purpose. Although these products also contain cement, they bind the water particularly quickly. This prevents the cement from settling via the water in the sensitive and porous surface and causing discoloration. In addition, the adhesive is usually white or transparent, which does not affect the appearance of the natural stone tiles.

Fluid bed adhesive

When laying tiles on large floor areas, special cement adhesives are also frequently used: the so-called fluidised bed adhesives. Their consistency can be flexibly varied between more or less liquid, depending on the amount of water added, so that they are – as the name suggests – suitable for fluid beds. This means that they do not have to be applied to each tile separately like the otherwise much more viscous standard tile adhesives, but can be spread directly on the floor. Since the back of the tiles is completely wetted with adhesive with this laying method, cavities under the tiles can be excluded. That is why fluidised bed adhesives not only provide optimum adhesion for large-format tiles, but are also ideal for outdoor applications. This is because cavities can quickly lead to frost damage, especially in these areas.

Non-cement-based tile adhesives

As this article is about an overview of the different types of tile adhesives, the repertoire of course also includes non-cement-based adhesives. However, this is more for the sake of completeness, as in practice these play a rather minor role.

Dispersion adhesive

Dispersion adhesives are water-soluble tile adhesives based on plastics, which are usually already available as ready-to-use mixtures. The biggest advantage of these adhesives is that they are more flexible after curing and have a higher adhesive strength than cement mortar. For this reason, dispersion adhesives are also mostly used on smooth surfaces (e.g. plasterboard or rigid foam).

On the other hand, there are also significant disadvantages: dispersion adhesives are not frost-resistant and are therefore only suitable for indoor use. And even there there are certain restrictions: Dispersions do not harden by setting like cement, but by drying, which makes the process much longer. For wall tiles this does not play a major role in principle, but dispersion adhesives are less recommended for the laying of floor tiles for this reason.

Reaction resin adhesive

Reaction resin adhesives can be useful primarily in commercial areas where particularly high demands are placed on the tile adhesive (e.g. commercial kitchens, laboratories, industry, etc.). Due to their excellent adhesive performance and high flexibility, they are not only suitable for critical substrates such as plastic, metal or glass, but are also resistant to chemicals.

However, reaction resin adhesives are hardly to be found in the private sector. Not least because of their complex processing: they consist of two components (synthetic resin and hardener), which must be joined together before a chemical reaction can finally ensure curing.

When buying tile adhesive, the following applies: Pay attention to the brand

Once the question of the appropriate type of tile adhesive has been clarified, it is “only” a matter of selecting the specific product. It definitely does not fail because of the selection. Because no matter whether in the DIY store or in the online shop – products are available in abundance.

The recommendation here is quite clear: quality before price. Or to put it another way: If you want to play it safe, you can also rely on branded products from well-known manufacturers, such as

  • Ardex
  • CMI
  • Knob
  • Lugato
  • MEM
  • PCI
  • Sopro
  • U. v. m.

These probably cost a little more than private labels or no-name products. But for the price you will certainly also get products made from higher quality raw materials, which usually meet all the necessary quality criteria according to DIN EN 2004. Many brand manufacturers also offer their customers a free service hotline for questions and support before or during installation.

Speaking of embarrassing: One final word of advice.

Which tooth size for which tiles?

Whereas tiles used to be fixed to walls or floors with a good portion of mortar, this is now usually done using the thin-bed method. The tile adhesive is applied over the entire surface using a toothed trowel. The size of the teeth depends on the tile format and also has an effect on the tile adhesive requirement. The exact recommendations can be found in the manufacturer’s specifications, whereby the following applies as a general guideline:

Tile edge length up to 100 mm: 6 mm tooth size

Tile edge length 100 to 200 mm: 8 mm tooth size

Tile edge length 200 to 300 mm: 10 mm tooth size

Tile edge length from 300 mm: 12 mm tooth size

As technically sophisticated as the production and firing process of tiles has become, it is not impossible that slight normal deviations in dimensions may occur. This is quite simply because tiles are produced at very high temperatures while at the same time enormous pressure is applied. However, in order to achieve the most accurate result possible during installation, such deviations are undesirable.

Because they lead to the fact that with jointing mortar for tiles, corresponding levelling must be carried out, which in many cases unfortunately becomes optically visible in the form of joints of varying width. This applies to both floor and wall tiles.

But there are solutions for exactly this dilemma, namely calibrated or better yet rectified tiles. For both types an additional edge processing takes place in order to create tiles that are as identical as possible. Whether calibrated or rectified tiles are preferred for a particular project depends primarily on the final desired width of the joint. Rectified models enable a much more precise result.

What happens during calibration?

Calibrated tiles have meanwhile become the standard product . This refers to the exact adjustment of the tiles to the desired size. Cutting is usually carried out in such a way that edges are created at an angle of 90 degrees. In principle, however, other production dimensions are also conceivable. Calibration is often used for natural stones or ceramic tiles.

If the calibration is carried out as precisely as possible, the joints between the tiles can be very small. Sometimes, however, this is not even desired or necessary (e.g. in the case of polygonal tiles laid in mosaic style).

What is a rectified tile?

For rectified tiles an additional correction takes place after production: With the help of diamond saws they are precisely ground. This means that no deviations or unevenness remains on the edges after the machine finishing and all tiles have the same dimensions.

By rectifying tiles, you give them a sharp 90 degree edge. As a result, it is easy to lay tile after tile and the joints are very narrow, which is often preferred in the area of floor tiles.

Rectified tiles are always marked with the addition “Rettificato” as a quality feature.

What are the advantages and do rectified tiles have disadvantages?

On the one hand, due to the straight edge, they allow an exact and simplified installation as well as a homogeneous joint pattern with a filigree joint dimension of less than 2 mm width. This is particularly important for large areas, so that exact calculations can be made and no shifts occur. In order to obtain a precise result, it is of course still necessary to work with spacers for the joints in rectified models. The overall optical result is then flawless.

Due to the further processing step, however, rectified tiles are naturally more expensive. Especially for less experienced people, laying with calibrated tiles is therefore much easier, as they allow a more flexible joint width and require less precision. The slight variations in the edges underline the desired design, especially in the case of tiles with a natural look, so custom-made Rettificato models are less suitable for this.

Whether to choose rectified or calibrated is therefore ultimately not only a financial but also a technical decision and depends on the width of the joint. The bottom line is that tiles are easy to lay when they are rectified, but it also means that precise procedures are essential.

Before this consideration can take place, it is important to choose the correct tile for the particular need and to be well informed about the different options and respective advantages. A distinction is generally made between stoneware, earthenware and porcelain stoneware tiles, with the latter variant in particular being increasingly used for floor and wall tiles in living rooms and bathrooms, as well as for stair coverings.

The outstanding breaking strength of the mixture of feldspar, sand and clay used in its production makes fine stoneware tiles also ideal for outdoor applications, for example for laying garden paths or terraces. There is also an almost endless range of possibilities in terms of slip resistance, weather resistance and, of course, design.

What does lappato mean in tiles?

The Lappato technique can be applied to porcelain stoneware tiles and refers to the partial polishing of the tiles. Since this does not happen over the whole surface, beautiful transitions are created that look like a silky shimmer.

This effect is particularly effective on large surfaces and with narrow joints between the individual tiles. In any case, Lappato tiles should be laid indoors. Although the slip resistance is higher than that of polished tiles, the requirements are even higher for tiles in outdoor areas.