Instructions for installing KERDI included on this page are for representative purposes only. For floor applications, please refer to the Waterproofing Membranes technical data sheet for installation guidelines, product information, and warranty criteria. Refer to the Schluter®-Shower System Installation Handbook for shower assembly details, requirements, and warranty criteria. You can contact Schluter®-Systems (USA: 800-472-4588; Canada: 800-667-8746) for copies of these documents, or download them from our download section above. The Schluter technical literature should be consulted before beginning product installation.

KERDI Installation Instructions:

  1. The substrate must be clean, even, and load bearing. The thin-set mortar used for bonding KERDI must be appropriate for the substrate, and it must penetrate and engage the KERDI fleece. Generally, an unmodified thin-set mortar is used. Cut KERDI to size prior to application.
  2. Apply thin-set mortar to the substrate using a 1/4" x 3/16" (6 mm x 5 mm) V-notched trowel or the Schluter®-KERDI-TROWEL, which features a 1/8" x 1/8" (3 mm x 3 mm) square-notched design (Note the open time of the mortar). Press KERDI fully into the bond coat. Work the KERDI into the mortar by applying pressure to the membrane with the flat side of the trowel (held at an angle) in smooth, diagonal sweeps. Air bubbles must be removed.
  3. Seams can be constructed by overlapping the edges of the KERDI by 2" (5 cm) using unmodified thin-set mortar, or by abutting the edges and covering the joint with Schluter®-KERDI-BAND using an unmodified thin-set mortar.
  4. For inside and outside corners, adhere preformed Schluter®-KERDI-KERECK-F corners. For floor/wall connections, use KERDI-BAND. Install Schluter®-KERDI-SEAL-PS pipe seals at the showerhead, body sprays, etc. and Schluter®-KERDI-SEAL-MV at the mixing valve. As an alternative to KERDI-SEAL-PS/-MV, Schluter®-KERDI-FIX or other suitable sealant can be used to seal pipe protrusions and protect moisture-sensitive solid backing panels at the mixing valve.
  5. Connections to fixed building elements can be achieved by using KERDI, KERDI-BAND, or KERDI-FLEX in conjunction with KERDI-FIX, suitable trowel-applied waterproofing materials (such as urethane or similar), that require atmospheric moisture to cure, or other suitable sealing compounds.
  6. KERDI shall be separated at existing expansion, structural, and flexible edge joints. Cover the joints with KERDI-FLEX. To allow for greater movement, the center section of the KERDI-FLEX can be tucked into the cavity of the expansion joint prior to bonding.
  7. Once the entire membrane — with seams, corners, and connections — has been completely bonded, and therefore waterproofed, the covering may be applied.

    Note: Water testing of the assembly
    Prior to setting tile, wait 24 hours to allow for final set of the mortar before testing to ensure waterproof performance of the assembly at seams and connections.

  8. For tile installations using the thin-bed method, apply unmodified thin-set mortar directly to the exposed KERDI surface and install the tiles, ensuring full coverage. For acid-resistant coverings, use an epoxy adhesive to set and grout the tile.

Connection to Schluter®-KERDI-DRAIN

KERDI-DRAIN is a floor drain specifically designed to allow connections to KERDI or other bonded waterproof membranes, typically in shower applications. When adhering KERDI to KERDI-DRAIN, the membrane must be held back to the step in the fleeced bonding flange. Apply unmodified thin-set mortar to the bonding flange using a 1/4" x 3/16" (6 mm x 5 mm) V-notched trowel or the KERDI-TROWEL, which features a 1/8" x 1/8" (3 mm x 3 mm) square-notched design. Firmly press KERDI into the mortar with the flat side of the trowel to ensure 100% coverage and a watertight seal. When using the stainless steel KERDI-DRAIN bonding flange, KERDI is adhered to the flange with KERDI-FIX. The flange must be clean and free of grease or other contaminants prior to KERDI-FIX application.