Schlüter®-DITRA 25 | Installation | Schlüter-Systems

Schlüter®-DITRA 25


  1. The substrate must be free of bond inhibiting components, be load bearing and even. Any unevenness in the substrate must be levelled prior to the application of Schlüter®-DITRA 25.
  2. The type of bonding adhesive used to apply Schlüter®-DITRA 25 depends on the type of substrate. The adhesive must bond to the substrate and mechanically anchor the fleece on the underside of the Schlüter®-DITRA 25 matting. Verify the compatibility of all materials prior to installation.
  3. Apply the bonding adhesive to the substrate using a 3 x 3 mm or 4 x 4 mm notched trowel.
  4. Individual courses of Schlüter®-DITRA 25 are cut to size. Solidly embed the anchoring fleece on the underside of Schlüter®-DITRA 25 in the adhesive so that its entire surface is bonded and immediately work it into the adhesive using a float or screed trowel. Please observe the open time of the bonding adhesive. When initially positioning Schlüter®-DITRA 25, it is advisable to align and position the matting while slightly stretching it. Application is made easier with a second person. The side edges and ends of individual courses are cut straight and abutted.
    Note: If Schlüter®-DITRA 25 is only installed as an uncoupling membrane, side edges and ends of individual courses do not need to be sealed with Schlüter®-KERDI-KEBA. Please refer to the instructions for waterproofing if the membrane is to serve as a waterproofing layer.
  5. Once installed, the matting must be protected against heavy mechanical loads to avoid loosening it from the substrate or other damage. It is advisable to place running boards (especially in the centre of material transports) to protect Schlüter®-DITRA 25. Other protective measures, such as shielding of direct sunlight or protection from precipitation in exterior applications, may also be required. Carefully remove any moisture that may have gathered in the indentations of the studs before applying the thin-bed tile adhesive.
  6. Immediately after the Schlüter®-DITRA 25 matting is installed, the tiles can be set using the thin-bed method and using a bonding tile adhesive that matches the requirements of the covering. It is recommeded to fill the square cavities with the smooth side of the trowel and to establish a regular pattern in the bonding adhesive with the notched side of the trowel in one application. The tiles are fully embedded in the adhesive. Fully embedded installation of tiles in accordance with the applicable professional standards is particularly important for coverings with high traffic loads and in outdoor areas. The notches of the trowel must match the format and thickness of the tiles, so as to achieve solid bedding. Please observe the open time of the adhesive. The adhesive bed over Schlüter®-DITRA 25 should not exceed 10 mm.
  7. For movement joints as control joints, expansion joints, or connection joints please follow the instructions given in this product data sheet as well as the applicable industry regulations.


The thin-bed adhesive and the covering materials selected for use with Schlüter®- DITRA 25 must be suitable for the corresponding application and must meet the requirements of the site. Materials used in exterior applications must be waterproof as well as resistant to frost and weather.

Schlüter®-DITRA 25 should be used primarily as a waterproofing layer when installing cover materials that are sensitive to moisture (e.g. natural stone or synthetic resin panels) or if moisture is expected to build up on the underside (e.g. in the case of green screed). When Schlüter®-DITRA 25 is installed in exterior applications, special protective measures may be required; e.g. shielding the installation from direct sunlight. The use of rapid setting thin-bed adhesives may be an advantage for certain projects.

Schlüter®-DITRA 25 should be covered with protective running boards if the transport of material makes it necessary to walk over the matting.

Movement Joints

Schlüter®-DITRA 25 must be separated at existing movement joints. If Schlüter®-DITRA 25 is used as a waterproofing layer, the joints between the sheets must be covered with Schlüter®-KERDI-FLEX band.

Movement joints must be continued in the tile covering, as specified by the applicable industry standards. In all other cases, large area floor assemblies installed over Schlüter®-DITRA 25 must be subdivided into smaller fields with the help of movement joints. The distance between such control joints in exterior applications (balconies and terraces) should not exceed three metres. Depending on the construction of the substrate, field sizes may need to be smaller. Please refer to our Schlüter®-DILEX profile range. Install the corresponding profiles such as Schlüter®-DILEX-BT or Schlüter®-DILEX-KSBT over expansion joints in accordance with the expected movements.

It must be assured that no tension can build at the edge of coverings, e.g. at upright construction elements or floor to wall transitions. The edge profiles and connective joints have to meet the requirements of the corresponding construction standards and must be suitable to prevent the build up of tensions. Please refer to our Schlüter®-DILEX profile range.

Contact Schlüter-Systems Ltd

Units 3-5 Bardon 22,
Beveridge Lane, Coalville,
Leicestershire, LE67 1TE
Phone: +44 (0) 1530 813396

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