Even ambitious craftsmen know: tiling is not that easy. It requires craftsmanship, experience and precise execution. Otherwise, mistakes can quickly happen that cannot be easily eradicated. So if you don’t think you can do it yourself, you should probably leave the laying to a professional. The decisive question in this context is then quickly: What will the tiler cost me? The answer to this question is revealed in this article.

What are the costs of tiling?

One thing in advance: It is not easy to give a general answer to the question of how much the laying of tiles by a professional actually costs. This is because the tiler price depends on several factors and can therefore vary greatly depending on the project.

What the tiling will cost is always influenced by the following three components:

  • Material
    • which tile manufacturer
  • Workload
  • possible additional services
    • must the substrate first be levelled with a leveling system for tiles?
    • must the substrate be levelled with a levelling compound for tiles?

These costs are usually quoted per square metre, which is also the most reliable basis of calculation for you as a customer. This allows you to estimate the total cost of tiling a given area when you request a quotation.

Material costs

The tiles themselves naturally account for the largest share of the material costs. The following applies: the price differences are just as large as the selection. While simple ceramic floor tiles or promotional items are already available from 5 to 10 euros per square metre, extravagant brand-name tiles or special formats, such as mosaic tiles, for example, can also be considerably more expensive at 70 to 100 euros per square metre. On average, however, high-quality tiles usually cost between 20 and 40 euros per m2. When making your choice, make sure that the tile is suitable for the desired application. You should pay particular attention to the tile abrasion class and in the bathroom or on the terrace additionally to the skid resistance of the tiles. This may increase the costs a little bit, but the higher quality is definitely worth it in these cases.

In addition, there is also the tile mortar or tile adhesive during laying or the grout. Depending on the size of the tiles, joint width and the filling material used for the expansion joints of the tiles, the costs per m 2 for this can be between 2 euros and 11 euros.

The total cost of the material depends, of course, on the surface on which you want to lay the tiles. Because on the one hand, this determines how many square metres of tiles you need, and on the other hand, what tile mortar or adhesive is required.

You can easily calculate a guide value for the material requirements:

For a floor installation, multiply the length and width of the room, for wall tiles take instead the height up to which the tiles should be placed. Also remember to allow for about 10 percent reserve for cuttings, breakage or later repairs.

Labour costs

The choice of tiles also influences how much the laying work costs. This is because tilers calculate the estimated work required with the corresponding tile and also convert this into costs per m2. In addition to the cost of laying tiles, the prices quoted per m 2 usually also include grouting and other necessary sealing work (e.g. silicone or acrylic joints). If not, this usually adds about 1 to 2 euros per meter.

The price per square meter is influenced by several factors:

Thus, floor plans that require complex cutting of the tiles increase costs just as much as special requests or complicated patterns. In addition, glued installation is in principle cheaper than laying tiles in a mortar bed. On the one hand, even large-format tiles often mean less work and correspondingly lower costs because they can be laid more quickly. On the other hand, however, they must also be aligned much more precisely, which at the same time increases the effort required. The trend towards particularly narrow joints, often associated with large tiles, can also increase costs.

As a rule, the cost of a tiler is between 30 euros and 50 euros per m 2. However, the above-mentioned influencing factors can by all means increase the costs per m 2 by another 10 to 20 euros. In addition, regional price differences may exist: For example, tiles are generally more expensive to lay in the city than in the countryside – and the well-known West-East divide also plays a role.

Some tilers prefer, especially for complicated orders, to charge according to actual time spent instead of a price per m 2. An example of this is the laying of tiles on stairs, as the amount of work involved here is above average in relation to the area. An hourly rate of at least 40 euros is normally customary in the industry, but the costs can sometimes be considerably higher depending on the requirements or qualifications of the tilers.

Additional services

In addition to material and installation work, additional costs may also be incurred. For example, you should check whether the offer already includes the filling and priming of the surface. This is because this work is required relatively frequently and can also cost around 5 euros per square metre extra. Also the installation of edge or skirting boards usually costs around 5 euros per meter extra. Not to be forgotten are possible costs for travel, construction site equipment or transport or delivery of the tiles.

Example: Costs for 20 square meters of tiles

On the basis of the cost factors for tiling, which have now been explained, the following exemplary calculation now shows what a tiler can cost for 20 m2 :

  • Tiles (porcelain stoneware, abrasion class 2, non-slip, EUR 30,-/m2) 600,- Euro
  • Tile adhesive (permanently elastic, EUR 7,-/m2) 140,- Euro
  • Filling and priming (extra charge, EUR 5,-/m2) 100,- Euro
  • Labour costs for tilers (EUR 40,-/m2) 800,- Euro
  • Additional services (installing skirting boards, setting silicone joints) 150,- Euro
  • Journey all-inclusive 70,- Euro

Total for 20 m2 Have tiles laid 1,860.- Euro

The best saving tips when tiling

All in all, it can be quite expensive to hire a tiler. Therefore we have a few tips on how you can reduce costs:

  1. It pays to compare prices
  2. You can also save on the installation itself, for example by dispensing with elaborate installation patterns or by not selecting a joint width that is too small.
  3. Avoid billing on an hourly rate to avoid unforeseeable cost developments. Instead, it is better to agree on a flat rate if a price per square metre is not possible.
  4. In addition, you can already make some advance payments yourself, which the tiler would otherwise charge for. For example, you can prepare the substrate by cleaning, smoothing and priming it yourself.
  5. You can also do the grouting or sealing with silicone yourself. Compared to tiling itself, this is almost child’s play.

Tiles convince not only by their attractive appearance and durability, but above all by their durability. Optimum adhesion to the substrate is the be-all and end-all – and for this you need the right conditions. In this article, you will learn how to ensure that your tiles have a lasting hold and what a decisive role the primer plays in this context.

The right substrate for tiles

Whether cement, concrete, plaster or even tile on tile in the bathroom – in principle, you can lay tiles on almost any surface. The prerequisite, however, is that they are clean, dry, flat and stable.

For example, when laying a new screed, it is essential to allow time for the tiles to fall below a certain residual moisture content and for the floor to be ready for laying. While, on the other hand, when laying tiles on top of tiles, you must first create a sufficiently even surface – preferably by using tile levelling compound, which you use to cover the old tiles.

But that’s not all. Because in most cases, an optimally prepared substrate also includes the right primer.

Primer – why actually?

If we were to ask you what actually makes tiles stick, tile adhesive would probably be your first answer. Basically, this is not wrong of course – after all, you can use it to attach the tiles to the wall or floor. But then it is not quite right either. Because the adhesive alone does not provide good adhesion.

In order to ensure that the tiles actually remain permanently bonded, you must first ensure that the substrate is evenly absorbent to increase the effect of the tile adhesive or even create it in the first place. And that is exactly what the primer is for.

Which primer for which substrate?

In principle, a distinction is made between the categories of deep primer and adhesive primer. The various products, which are available in a wide range of ready-to-use products in specialist shops, differ both in their composition and in the type of surface on which they can be applied:

Deep base for highly absorbent material

Highly absorbent substrates, such as plaster or cement, draw water from the tile adhesive – with potentially unpleasant consequences during and after installation. On the one hand, the adhesive hardens faster, leaving you less time to install the wall or floor tiles. On the other hand, the adhesive effect can be impaired, which in turn leads to less adhesion of the tiles. In these cases, therefore, a pre-treatment with Tiefengrund forms the basis for a permanently perfect result when tiling.

Tiefengrund is usually a liquid primer based on synthetic resin, which is applied to the substrate diluted with water or undiluted, depending on the manufacturer’s information. It penetrates deep into the surface, solidifies the material and thus reduces its absorbency. In this way, the primer not only helps the tiles to adhere better, but also protects against too much penetrating moisture under the tiles.

Primer for smooth surfaces

In contrast, primer is used on non-absorbent or only weakly absorbent, smooth surfaces on which bonded tiles would normally not hold sufficiently.

This type of primer provides optimal conditions, especially for surfaces made of concrete, metal or even screeds made of mastic asphalt. In addition, existing tiles can also be treated with primer to ensure the necessary adhesion when laying tile on tile.

Adhesion primer consists of coarse-grained mortar with binding agents, which serves as a bonding agent between tile and adhesive. Unlike Tiefengrund, Haftgrund does not penetrate very deeply into the surface.

The best tips for an optimal primer

1. determine the absorbency of the substrate

Before priming your wall or floor, you should first test the absorbency of your substrate. With the so-called scratch test this can be tested well and easily: The easier and deeper you can prick the surface with a screwdriver or other sharp object, the more absorbent it is.

Another possibility is the water test, in which you moisten a small area of the substrate. If a dark discoloration is visible, you are also dealing with a highly absorbent material.

2. choose a suitable primer

On the shelves of DIY stores, but also in various online shops, you will find countless different products for priming. You can find out which of these is the right one for the condition of your surface from the manufacturer’s information. In addition, the primer and adhesive must be compatible. Ideally, therefore, only products of a system should end up in your shopping cart.

3. apply primer step by step

Before the primer can be applied, dust, dirt and material residues must be carefully removed from floors or walls. For the priming itself, it is best to use a paint roller or ceiling brush to achieve the most even result. Alternatively, you can also use a brush or a spray bottle.

In case of highly absorbent surfaces or larger damages, it is recommended to apply at least two coats of primer (first diluted and then undiluted) – more if necessary. Make sure that the first layer is sufficiently dry before applying the next one. All necessary information about the drying time can be found in the manufacturer’s instructions. When the primer is dry, you can start laying the tiles.

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.