Expansion joints is the decisive keyword for a permanently beautiful and damage-free tiled floor. After all, like almost any other material, tiles need sufficient room to move to be able to work. In this article you can read about the important functions of an expansion joint, where it is required and how best to create it.

Why do you need expansion joints?

Tiles consist mainly of natural raw materials that react to external influences. Temperature fluctuations or the application of force cause the plates to work: The material expands and contracts according to the ambient conditions. However, this reaction behaviour is not a unique phenomenon of the tile, but occurs always and everywhere where different building and material materials meet.

This is exactly the point why expansion joints are so important when laying tiles. They serve as a buffer to compensate for the movements of the different materials without the components colliding with each other. At the same time, expansion joints have another function: they dampen sound because they reduce the transmission of vibrations.

What happens if the expansion joint is missing?

As low as the expansion and shrinkage behaviour of tiles may be, it can be unpleasant if expansion joints are not taken into account accordingly. Although the changes are usually barely perceptible to the human eye, they do increase the pressure on the individual plates.

This causes stresses on the surface, which in turn can cause cracks in the tiles. And sometimes not even directly where the joint is missing, but – due to the transmission of force – in a completely different place. Therefore even adjacent floor coverings or the screed can be damaged if the corresponding joints are not set.

For which tiles are expansion joints necessary?

Expansion joints – often also called movement joints, expansion joints or dilatation joints – are to be considered in principle for all tile floors. No matter whether it is natural stone, earthenware, stoneware or porcelain stoneware. Also the substrate or the tile adhesive or tile bonding primer used during installation have no influence on the necessity of the joints.

Where should an expansion joint be placed?

Specifically, expansion joints must always be created when different components come together. This primarily concerns all transitions to rooms (e.g. door thresholds) and between different floor coverings (e.g. B. tiles and parquet), but also areas which are only partially tiled (e.g. around a tiled stove or fireplace) or which adjoin rigid elements (e.g. radiators or fittings).

Edge joints as a connection area to the wall are also considered expansion joints and must therefore always be taken into account accordingly. In addition to their compensatory function when expanding, they also ensure that the impact sound is not transmitted to the wall and thus into the room. This is one of the reasons why they should be regularly maintained and checked for their condition or tightness (to protect against moisture under the tiles).

Important: Interaction of expansion joint & observe screed!

Existing expansion joints from the screed must also be taken over in the tiled floor – and in the same position. This applies both to the initial laying of tiles and slabs and to subsequent renovations. Only then can it be guaranteed that the substrate also has sufficient room to move and that the materials can work independently of each other according to their properties. This avoids cracks or fractures that could otherwise sooner or later be transferred to the tiles. Where these joints should be planned exactly is usually announced by the screed layer.

By the way: A term that also appears again and again in connection with the screed are the so-called dummy joints. Although these serve a similar purpose to expansion joints, they are not actually expansion joints. Rather, these are deliberately placed predetermined breaking points that specifically control the further course of possible cracks in the screed.

From which room size are expansion joints required?

The formation of expansion joints is regulated according to DIN standards. Accordingly, field boundary joints are prescribed for rooms with a size of 40 m2, whereby the field length and width should be between 5 and 8 m at the most. In this context, the room geometry, the tile format used and the expected stress on the floor must be taken into account. If the room has a floor heating under the tiles, the arrangement of the heating circuits must also be taken into account.

In general, the recommendation is to work in expansion joints vertically and horizontally at intervals of 3 to 6 m. For larger areas and tiles in outdoor areas, joints should be planned around every 4 m, as the expansion of the tiles can be even greater there than indoors due to higher temperature differences.

How wide must an expansion joint be?

The width of the joints depends on the tile format as well as on the respective position. The limit values recommended by the DIN standard again serve as a guideline:

Especially in the edge areas to the wall or wherever the tiles are adjacent to other rigid components, a width of 5 mm should not be undercut under any circumstances. To be on the safe side, in this case it is even better to increase to 8 mm. Professional planning and exact calculation of the joint dimensions is definitely advisable.

Excursus: Attention with narrow joints!

However, since the joint pattern in a room also has visual effects, care should be taken to ensure a balanced distribution and the most uniform width possible of all necessary joints. In particular, the continuing trend towards large-format tiles with very narrow construction joints – i.e. the distance at which the tiles are placed on the floor during installation – can sometimes become a problem.

On the one hand, because the considerably wider expansion joints can quickly look unsightly in comparison and thus disturb the overall harmonious impression. On the other hand, the narrower the joints are, the more difficult it is to grout – and improper execution impairs the quality of the joints.

If too much water is added to the jointing mortar to make it more fluid, this can lead to differences in colour and spots in the joints due to different drying phases. While too little water, on the other hand, makes the joint sealant brittle. For this reason, filling with conventional, cementitious jointing compound is only possible from a width of at least 2 mm. Among these, only highly viscous materials with a synthetic resin content can be used, as these are more elastic and can be worked into the joint more easily.

And even otherwise, very narrow joints entail an increased risk of damage. This is because if the proportion of joints is small, moisture can only escape from the floor very slowly on the one hand and on the other hand, tensions are less well balanced.

How is an expansion joint correctly filled?

In order to be able to compensate for the movements of the tiles, expansion joints may only be sealed with permanently elastic sealants. The best known and most frequently used material for this is silicone. The best possible result is achieved if the joint sealing compound is applied as deep as the joint is wide – otherwise, too deep filling can have a negative effect on the elasticity. Tip: You can work particularly precisely if the tip of the cartridge is simply cut to the appropriate joint width.

Since the silicone must not adhere to the substrate under any circumstances, expansion profiles made of foam or plastic are also recommended. These are pressed into the joint before filling and fixed at the edges with adhesive tape. Alternatively, paper strips can also be used.

Practical side effect: In this way, the material requirement is also minimized.

Before filling, dust, dirt or adhesive residues must be thoroughly removed from the joint. This is especially true when existing expansion joints are renewed: They must be carefully scraped out before the new filling material is applied.

After the joint has been sealed, the joint sealing compound is evenly removed with a smoothing trowel. Finally, the attached adhesive tape is peeled off and the excess joint sealing compound and any adhesive residues are removed with a damp sponge.

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.