Home generalDecoupling mat - Information and installation instructions

Decoupling mat - Information and installation instructions

  • Information about the decoupling mat
    • advantages
  • Structure and structure
    • characteristics
  • Lay decoupling mats
  • disposal
  • Tips for quick readers

A decoupling mat is unknown to many DIY tile makers. This easy-to-use feature is very convenient and can help prevent many consequential damage. In this guide we show what to look for when laying decoupling mats.

Heraclitus in putty - "Pantha Rei - Everything flows". This wisdom from the Greek philosopher Heraclitus is still valid after 2, 500 years. Even the seemingly rigid and solid tiles expand when heated and contract again when cooled. Especially with large floor tiles, this inevitable effect can lead to massive problems. With luck, only the fugue breaks and the tile comes off the ground. Most of the time, however, the tiles suddenly break through in the middle, creating an ugly jump. At this water can penetrate, which ensures a progressive destruction of the tile floor. That's why professional tilers are now using standard decoupling mats when creating a new tiling.

Information about the decoupling mat

The decoupling mat is a flexible layer of rubber or foam, which is installed between tiled surface and underground. It gives the tiling the opportunity to expand in any direction. Although these strains are only fractions of a millimeter, they provide the dreaded tensions between the pavement and the substrate. The decoupling mat prevents or reduces these stresses so far that no cracks or delamination in the coating can occur more. With little additional effort, the decoupling mat can be upgraded to a full barrier against moisture penetration.


Decoupling mats are actually always a meaningful contribution to a durable tiling. In some cases, however, their installation is particularly urgent. These cases are:

  • swinging underground
  • large areas
  • big tiles
  • exteriors
  • strong, occasional fluctuations in temperature

An oscillating surface is present, for example, in a floorboard floor. If the ground can yield even slightly, removing a rigid tile floor is only a matter of time. With the decoupling this replacement is effectively prevented. With decoupling mats, for example, old half-timbered houses can be equipped with modern bathrooms.

For particularly large tiled surfaces, the development of longitudinal stresses is virtually unavoidable. The rigid tiles and also very little flexible joint mortar stretch under the influence of heat. Calculated over a large area, this extent can already be a few millimeters. With expansion joints, which should be introduced every 3-6 meters, the emergence of these stresses can be reduced. Real safety, however, only the installation of the decoupling mat. This is especially true when large tiles are used. The cumulative elongation is the more serious, the larger the plates used.

In outdoor areas, the issues of temperature variation and frost formation are particularly serious. Since tiled outdoor areas, such as pools or terraces, are usually also very large, the formation of tensions in the tiling is particularly serious. Decoupling mats provide a dense and flexible surface.

Heating pipes laid in the floor can produce strong, punctiform warming. Then the tiles no longer expand evenly with a continuous covering. Tension formation is inevitable in this case. Decoupling mats contribute to longevity so that even demanding environments can be tiled.

When do you need no decoupling mat ">

Underfloor heating with decoupling

Structure and structure

Decoupling mats consist of approx. 2 mm thick foils made of plastic, rubber or foam. They are heavily knopped on both sides in order to absorb tile adhesive well. The flexibility is due to its rubbery core. Decoupling mats are supplied in rolls. In the area they are waterproof. But in order to protect the entire surface against penetrating moisture, the shocks must be sealed. However, decoupling mats are not cheap: a roll costs about 300 euros, which is about 10 euros per square meter. For this you get a durable tile floor covering.


There are many manufacturers who offer mats for decoupling the tiling. Except that they all cost about the same, the different products in places have little in common with each other. In order for the decoupling mat to actually fulfill its function, it must have four properties:

  • elasticity
  • dense surface
  • rough structure
  • rot

Some manufacturers offer net-like rubber mats as decoupling mats. However, these are neither watertight, nor do they produce a truly effective decoupling between the substrate and the tiled surface. Fleece mats are also often not waterproof. A truly effective decoupling mat offers the described properties. You should pay attention to this when buying.

Lay decoupling mats

To lay decoupling mats correctly you need the following material:

  • Measuring tape or folding rule (about 5 Euro)
  • Sufficient decoupling mats for full-surface installation in the room (about 10 euros per square meter)
  • Edge strips (about 15 euros per 10-meter roll)
  • Tile adhesive (about 5 Euro)
  • Cutter (about 5 Euro)
  • Tooth spatula 3 mm at least, better 4 mm toothing (about 12 Euro)
  • Bucket (about 5 euros)
  • Whisk (about 5 euros + drill 150 euros)
  • Mat pressure roller (6-200 Euro)
  • Sealing tapes (about 1.50 euros per meter)

1. Preparation

The room must be clean and the floor level. There must be no bumps. Up to 4 mm depth, holes in the floor can be filled with tile adhesive. The entire floor must not be solvable. Loose spots must first be knocked off with a hammer and repacked. Then the room is swept and wiped damp, so that no loose dust rests. A moistened soil is conducive to the adhesion of the tile adhesive.

2. Measure the mats and attach the edge strips

The mats are measured before laying and precisely cut. Since the mats are very expensive, care should be taken here. Dry presentation creates the necessary security. With complicated layouts of the room, it helps to number the mats and to make a laying plan. The edge strip is then attached to the wall all around. It is sufficient to fasten the edge strips every 20 cm with small nails. The fixation takes place later when applying the tile adhesive.

3. Apply tile adhesive and insert the mat

The tile adhesive is mixed with bucket and whisk in accordance with the processing instructions as they can be found on the package. It is very important to stir and process the glue only gradually. Tile adhesive binds very quickly. If applied tile adhesive has already formed a skin, it is useless and must be removed.

The freshly applied tile adhesive is applied with trowel and spatula and the mat inserted as quickly as possible. The mat must be pressed firmly into the tile adhesive immediately after insertion. A wallpaper roller for 6 euros is possible for this work, but very tight. Better are high-strength pressure rollers for roofers. These have a particularly robust construction and a heavy metal roller. Roof-board pressure rollers cost from approx. 35 Euro. Ideal for this purpose, however, are the DITRA pressure rollers. They have the advantage that they are equipped with a handle and thus you can work standing or walking. In addition, these special pressure rollers have a holding device for cement bags. The pressure roller can be loaded with up to 35 kg. That guarantees a good result. The scooter is very wide, which makes the work more efficient than with a narrow hand roller. Unfortunately, the DITRA-Andruckroller is over 200 euros very expensive.

It pays to ask the appropriate specialist companies if they can possibly rent the device. When processing a large, tiled area, this investment should be considered. The DITA pressure roller makes work a lot easier.

So that the decoupling mats are really firmly anchored to the ground, the connection should be checked. To do this, you simply pull the mat off a corner again. If the fleece is completely wetted, the installation was correct. However, if large areas are unwetted, the tile adhesive had already set too far. The thin-bed mortar must be removed in this case again and reapplied. The void-free installation of the decoupling mat is particularly important if the tiling is to be installed outdoors. Cavities under the tiles lead to the formation of duckweed, which burst open again during freezing the covering.

4. Seal mats

In order for the underlayer of the tile covering to be really watertight, the joints must be sealed after installation of the decoupling mats. For this purpose, sealing strips are used. They are glued in the middle of the joints along the edge along with the edge strips. For edge bonding, fold the sealing tapes once in the middle. This facilitates gluing in the corner.

The sealing tapes are glued with thin-bed mortar and pressed firmly with the pressure roller. When this job is done, leave the flooring to rest for at least three hours. Ideal is a rest period of 24 hours. Thus, the decoupling mats can not slip on entering.

5. Build up tiling

Before laying the tiles, the edge strip is cut off with the cutter. The supernatant material can easily be used in the next room.
The decoupling mats now form the substrate for the tile covering. Again, with the notched trowel step by step, ideally tile by tile, prepares the primer. As with the installation of the decoupling mats, the adhesion of the floor tiles should be checked. Only a rich, full-surface application of the tile guarantees a permanent connection to the floor. Once the tiles have been installed, let them rest for another day or two, so that they bond firmly to the substrate. Then the tile floor can be grouted with grout. Despite the decoupling, it is useful for large rooms and large tiles to install an expansion joint every 3-6 meters. Also on the side edge of the tiled surface is grouted with silicone. This eliminates all risks of cracks and detachments due to build-up of tension.


A law amendment has made the disposal of polystyrene very difficult. It is therefore strongly recommended that only decoupling mats be used that are safe to dispose of or can be dumped. The receipts and data sheets of the building materials used should therefore necessarily be kept in order to provide the necessary evidence in the event of a return or conversion.

Tips for quick readers

  • Prevent decoupling mats as a precaution
  • In underfloor heating can be dispensed with an additional decoupling.
  • Not only decouple surfaces, but also waterproof them
  • Generously dimensioning the pressure rollers
  • Apply glue only in sections and sections
  • In case of skin formation, remove the thin-bed mortar and apply fresh
  • Check the quality of the connections
  • Decoupling mats for one day
  • Allow tiling to rest for two days before grouting
  • In spite of decoupling, install expansion joints
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