Schlüter-KERDI-DS  Polyethylene waterproofing and vapour barrier

Whether for a swimming pool or spa area, KERDI-DS, the KERDI waterproofing membrane with additional vapour barrier properties, is the product to use in areas with increased levels of humidity. You can also apply the special membrane to moisture-sensitive substrates, such as wood, to protect them.

KERDI-DS also offers the same benefits as KERDI. These include:

  • Fleece laminated on both sides for optimal anchoring in the adhesive
  • Imprinted gridlines make it quick and easy to cut to the required size using a cutter knife

Product image KERDI-DS 1©Schlüter-Systems KG
Cross-section drawing KERDI-DS 1©Schlüter-Systems KG
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Product image KERDI-DS 1
Cross-section drawing KERDI-DS 1

General product information

What this product does

Schlüter-KERDI is a crack-bridging waterproofing membrane of soft polyethylene with a special fleece fabric laminated on both sides for effective anchoring in the tile adhesive.

KERDI features imprinted gridlines on one side for easier cutting. In addition to indicating how much material is left, the imprint also shows the minimum overlap width of 5 cm for working with multiple membrane sheets.

KERDI was developed for bonded waterproofing assemblies with ceramic tile and natural stone coverings and is therefore suitable for applications in accordance with the German standards DIN 18531*, DIN 18534 and DIN 18535*. Water exposure classes according to DIN 18534: W0-I to W3-I*. KERDI also features the national technical approval (abP) required in Germany.

Moisture load class according to ZDB: 0 to B0 as well as A, B and C.

KERDI features European Technical Approval (ETA) pursuant to ETAG 022 (watertight covering kits) and bears a CE mark.

* With abP and/or in compliance with ETA according to ETAG 022. The Technical Department is available to provide information on use and installation on request.

The waterproofing membrane should be bonded to an even, load bearing substrate with an appropriate adhesive. Tiles are then installed directly on KERDI, using the thin-bed method. Other suitable trowel-applied covering materials or plaster may also be used.

Schlüter-KERDI-DS is a waterproofing membrane and vapour barrier bonded to a tile covering, e.g. for use in swimming pools and spa areas, as well as for commercial applications with high humidity levels.

Vapour barriers are suggested for moisture-sensitive substrates such as wood, plasterboard and gypsum plaster.

Accessories for KERDI include internal and external corners as well as pipe collars, Schlüter-KERDI-KM and Schlüter-KERDI-MV. Schlüter-KERDI-PAS sets – consisting of a KERDI-MV collar and a special plastic sleeve – are available for installations involving existing pipe protrusions located within the waterproofing plane that are to be fitted with an internally threaded tap extension. To seal butt joints or corner joints, Schlüter-KERDI-KEBA, in widths of 8.5, 12.5, 15, 18.5 and 25 cm are available.

Schlüter-KERDI-FLEX, in widths of 12.5 cm or 25 cm, is used to seal over expansion joints or flexible edge joints.

How to install this product

  1. The substrate must be load-bearing, level and free of components that may inhibit bonding. Any necessary levelling work must be completed before installing Schlüter-KERDI.
  2. The type of bonding adhesive used to apply KERDI depends on the type of substrate. The adhesive must bond with the substrate and mechanically attach to the KERDI anchoring fleece. A dry setting cementitious tile adhesive can be used for most substrates. Verify the compatibility of all materials prior to installation. If using covering materials with a side length exceeding 30 cm, we recommend a water-binding tile adhesive for rapid curing and drying.
    Note: System tested adhesive must be used in areas that require special approval of the authorities.
  3. Apply the bonding adhesive the substrate with a notched trowel (recommended size: 3 x 3 mm or 4 x 4 mm).
  4. Solidly embed the KERDI membranes, which must have been cut to size beforehand, in the adhesive, creating a bond with the anchoring fleece. Firmly push the membrane in place with the smooth side of the notched trowel or by drawing a smoothing trowel over the KERDI membrane at an angle under pressure. Make sure there are no air bubbles. The curing time of the adhesive must be observed.
  5. Overlap the joints of the KERDI membranes by at least 5 cm or abut the joints and fully cover the joint with Schlüter-KERDI-KEBA, using the sealant adhesive Schlüter-KERDI-COLL-L.
  6. Use the prefabricated KERDI corners for internal and external corners. KERDI-KEBA must be adhered to corner joints in the same manner. KERDI-KEBA can also be used to create functional connections to fixed structural components. Depending on the situation of the construction site, Schlüter-KERDI, -KERDI-KEBA or -KERDI-FLEX can be attached to the adjoining structural element with Schlüter-KERDI-FIX to create a waterproof connection (see product data sheet 8.3 Schlüter-KERDI-FIX).
    1. Adhere Schlüter-KERDI-KM or Schlüter-KERDI-MV (pipe collars) around pipe penetrations.
      As an alternative, our Schlüter-KERDI-PAS sets comprise a plastic sleeve and a KERDI-MV collar. The collar is adhered around the pipe protrusion together with the plastic sleeve to ensure reliable waterproofing of the subsequently installed internally threaded tap extension after removing the plastic sleeve.
  7. Clamp or tightly adhere a 50 cm x 50 cm piece of KERDI onto the flange of the floor drains constructed in the thin-bed method as a connector collar. Then bring the KERDI mat within 10 cm of the floor drain and adhere it to the connector collar without leaving air pockets.

Note on floor drains:

Schlüter-KERDI-DRAIN and Schlüter-KERDI-LINE are special drainage systems designed for connection to bonded waterproofing assemblies. KERDI can easily and quickly be combined with these components by using prefabricated KERDI collars.

  1. Separate KERDI at existing movement joints or expansion joints and seal the abutting joints with KERDI-FLEX. KERDI-FLEX should also be used for flexible finishing edges. As an alternative, this can also be done with a sufficient loop of KERDI-KEBA.
  2. The covering can be installed as soon as the entire waterproofing assembly is tightly sealed at all overlaps, corners and joints. No curing time is required. Note: Do not attempt to remove the membrane before tiling as it may loosen the adhesive bond to the substrate.
  3. To install the tiles, apply the dry setting cementitious tile adhesive directly on the KERDI and then solidly embed the tiles in the adhesive.
    Suitable reactive resin adhesives and grout adhesive must be used for coverings that are likely to be exposed to chemicals.
    System-certified tile adhesives must be used in areas that require CE compliance or assemblies according to abP (certificate of technical approval). Please contact us for further information about such tile adhesive products and the corresponding certificates of technical approval.

Note on uncoupling:

Since bonded waterproofing assemblies with KERDI do not have the necessary uncoupling function for screed and tile coverings in outdoor areas that are subject to temperature changes, we recommend the use of KERDI in conjunction with Schlüter-DITRA-DRAIN (see product data sheet 6.2) or Schlüter-DITRA (see product data sheet 6.1) for a combined bonded waterproofing and uncoupling function.

What this product is made from

Schlüter-KERDI-DS is a special polyethylene membrane for bonded waterproofing assemblies and serves as a vapour barrier with an sd value of more than 100 m, which is considered a vapour barrier in physical construction terms. The waterproofing membrane is 0.5 mm thick and equipped with water vapour blocking additives.

The material is non-toxic and physiologically harmless. Cutting waste is not classified as hazardous waste. Polyethylene is not UV-stable in the long term; the product should not be stored in places with prolonged exposure to direct sunlight.

Material properties and areas of application

Schlüter-KERDI is waterproof and resistant to any chemical stresses that typically occur in conjunction with tiled coverings. KERDI is resistant to ageing, does not rot and is characterised by its elasticity.

In addition, it is largely resistant to saline solutions, acids and alkalis, many organic solvents, alcohols and oils.

Product resistance to loads in specific individual cases should be verified separately based on the anticipated concentration, temperature and length of exposure.

Verify that the substrate on which KERDI is to be placed is even, load-bearing and free from moisture. Remove all surface components that may weaken the bond.

KERDI is suitable for wall and floor surfaces where protection against the penetration of moisture or other harmful substances is necessary. Surfaces include bath tub surrounds, showers and areas surrounding swimming pools. Industrial applications include the food industry, breweries and dairies.

Swimming pools and similar structures are subject to special requirements. Please contact us for further information if you are planning this type of project.