Tiling - The topic of decoupling explained simply!

The Underground

Without the right substrate, nothing works. It forms the basis for the final result. Whether it's about aesthetics or the long-term adhesion of the tiles. Theoretically, you can lay tiles on any substrate. But beware! Different floors = different properties. This means that the respective preparatory work must be individually adapted to the substrate.

Generally speaking: The substrate must be firm, load-bearing, dust-free and dry. The surface should be even and any cracks must be filled.

Possible problems that may occur:

Cracks in the subsoil

When renovating old floors, cracks in the substrate may be present, making it impossible to safely lay a new tile covering.

Subsurface stresses

Depending on the structure and materials used, stresses can build up in the substrate, which are transferred to the tile covering and form cracks. For this reason, for example, concrete can still undergo shape changes after 6 months to several years. Cement and screed floors can also deform after being covered with tiles and slabs.

Moisture from below

When laying tiles on anhydrite screeds, residual moisture from the screed can accumulate under the tiles and damage the adhesive bond.

The solution: decoupling mats

Decoupling mats protect tiles and slabs from cracking. Especially with large formats, decoupling mats should not be omitted. Since floors can expand and contract due to temperature changes, it is always advisable to place a decoupling mat between the old and new floor to compensate for the different expansion rates of the materials. Who wants to lay a new floor that is damaged after a short time?

Suitable substrates for laying tiles include, among others:

1. Cement screed must be at least 28 days old and have a residual moisture content of < 2 CM-% before tiling, in accordance with the applicable regulations. However, heated screeds and floating screeds are still prone to deformation and cracking later on. With the DURAL decoupling mat CI++, cement screeds can be tiled as soon as they are sufficiently walkable.
2. Calcium sulfate screed (anhydrite screed) According to current regulations, the screed may only have a maximum of 0.5 CM% residual moisture when tiling. With the DURAL CI++ decoupling mat, calcium sulfate screeds can be tiled as soon as they have a residual moisture content of less than 2%. The screed surface must still be treated before tiling (sanding, priming, etc.).
3. Concrete is subject to a prolonged change in shape due to shrinkage (=shortening or reduction in volume of the concrete). Additional stresses can also occur in the concrete due to creep (=time and temperature-dependent viscoelastic deformation under constant load). With the DURAL decoupling mat CI++, the stresses between the concrete and the tile covering are absorbed, so that the tiles can be laid immediately after sufficient strength has been reached, depending on the concrete quality class. When laying the CI++ mat on young concrete, appropriate technical advice is necessary.
4. Plastic coatings and linings must have a load-bearing surface and be sufficiently firmly bonded to the substrate, and be such that a suitable adhesive adheres to it and can anchor itself to the carrier fleece of the decoupling mat. The compatibility of the adhesive with the substrate and the CI++ mat should be checked in advance.
5. Wooden floorboards must be sufficiently load-bearing and even in order to allow tiles to be laid directly in conjunction with the DURAL decoupling mat CI++. In the case of a wooden substrate, the equilibrium moisture content of approx. 15% should be ensured before DURABASE CI++ is laid. If the plank construction is unstable, it is recommended to apply correspondingly thick chipboard or pressed board. Unevenness must be compensated for directly on the wooden substrate with suitable filler compounds.

Dampening mat

Processing

1. When cutting the strips, care must be taken to ensure that neither the CI++ decoupling mat nor the associated ceramic tiles are clamped tightly due to thermally induced stresses and impact sound insulation. Depending on the tile construction and site conditions, edge joints with a width of approx. 5–10 mm (or larger if necessary) should be created.
2. Apply thin-bed mortar to the substrate using a 4 x 4 or 6 x 6 mm notched trowel. Important: Do not use a larger notched trowel, as this will impair the vapor pressure equalization of the CI++ mat. The choice of adhesive depends on the type of substrate. The adhesive must adhere to the substrate and mechanically interlock with the carrier fleece of the decoupling mat. For most substrates, a hydraulically setting flex mortar or a fast-setting flex adhesive according to DIN EN 12004 / C2 can be used.
3. The cut-to-size sheets must be fully embedded in the adhesive with the backing fleece. Loose laying of the CI++ mat is not possible. The sheet is worked in using a pressure roller or other suitable tool. The adhesive's open time must be observed. Pre-formed pieces should be used for inner and outer corners. Expansion joints can be incorporated using sealing tape (also available in our shop).
4. Indoors, tiles can be laid immediately after bonding the DURAL CI++ decoupling mat using the thin-bed method with a thin-bed mortar adapted to the requirements of the covering. For this purpose, it is advisable to fill the mat recesses with filler in one work step and then comb on the thin-bed mortar. The tooth depth of the trowel must be adapted to the tile format for tile laying. The tiles must be fully embedded in the adhesive. The specified open laying time of the thin-bed mortar must be observed. From a work perspective, it is also possible to proceed in such a way that tile laying is only started after the filler has hardened. For outdoor applications and heavily trafficked areas, as well as large-format tiles, tile laying should only begin after the CI++ filler has hardened! Tiles with thin material thicknesses (slim or slim/4 tiles) are unsuitable (risk of breakage). Furthermore, small-format tiles smaller than 5 x 5 cm must not be used. To prevent damage to the laid mat, it is recommended to protect it from mechanical stress by laying planks.

Notes:

In general, the generally accepted rules of technology must be observed!

For all products/materials: The suitability for mechanical and chemical stress must be carefully checked in each individual case before laying the mat. Protect material from prolonged exposure to sunlight.

If you have any further questions, please feel free to contact us.

Best of luck with the tiling!

The team from Everything for Tiles