Schluter®-KERDI is a pliable, sheet-applied, bonded waterproof membrane and vapor retarder with limited crack-bridging capabilities. KERDI features a modified polyethylene (PEVA) core with non-woven polypropylene on both sides to anchor the membrane in the thin-set mortar. KERDI was developed as a waterproofing membrane to be used in conjunction with ceramic and stone tile coverings. Tiles can be installed directly on KERDI using the thin-bed method. Other trowel-applied covering materials, such as plaster, can also be used.
KERDI has been evaluated according to the “Standard Method for the Testing and Evaluation of Volatile Organic Chemical Emissions from Indoor Sources Using Environmental Chambers, Version 1.1” for California Specification 01350 and found to comply with the VOC requirements. California Specification 01350 is referenced by various green building standards and rating systems.
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, Schluter-SET, Schluter-ALL-SET, Schluter-FAST-SET, or 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 x 5 mm) V-notched trowel or the KERDI-TROWEL, which features a 1/8" x 1/8" (3 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 avoided.
3. Seams can be constructed by overlapping the edges of the KERDI 2" (5 cm) using Schluter-SET, Schluter-ALL-SET, Schluter-FAST-SET, or unmodified thin-set mortar, or by abutting the edges and covering the joint with KERDI-BAND using Schluter-SET, Schluter-ALL-SET, Schluter-FAST-SET, or unmodified thin-set mortar.
4. For inside and outside corners, adhere pre-formed KERDI-KERECK-F corners. For floor/wall connections, use KERDI-BAND. Install KERDI-SEAL-PS pipe seals at showerhead, body sprays, etc. and KERDI-SEAL-MV at the mixing valve. As an alternative to KERDISEAL- PS/-MV, KERDI-FIX or other suitable sealant can be used to seal pipe protrusions and protect moisturesensitive 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 Schluter-SET, Schluter-ALL-SET, Schluter-FAST-SET, or 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.
For complete installation guidelines and warranty criteria for KERDI in showers, steam showers, and bathtub surrounds or KERDI-DS in steam rooms , please download the Schluter®- Systems Shower System Installation Handbook and view the installation videos available below.
How do I know if the thin-set mortar is modified or unmodified?
In general, unmodified thin-set mortar is a blend of Portland cement, sand, and water retention agents that is mixed with...Read more
How far up the wall do I need to install the Schluter®-KERDI?
For showers and bathtub surrounds, KERDI must be carried to the height of the showerhead at minimum...Read more
What size notched trowel should I use to install Schluter®-KERDI?
A 1/4" x 3/16" (6 mm x 5 mm) V-notched trowel or the Schluter™-KERDI-TROWEL is recommended..Read more
How do I seal Schluter®-KERDI to a bathtub?
There are two methods to seal KERDI to a bathtub. Please refer to the Schluter®-Shower System Installation Handbook...Read more
How long do I have to wait before I can install tile on the Schluter®-KERDI membrane?
Once the KERDI membrane, including seams, corners and protrusions have been completely bonded and, therefore, waterproofed...Read more
I installed my Schluter®-KERDI membrane yesterday. Why is it so easy to peel it off the wall today?
Thin-set mortar takes time to cure. The bond strength will increase over the first week and month after installation...Read more
Can ceramic tile, including porcelain tile, be set on Schluter®-KERDI with latex-modified thin-set mortar?
In general, we DON’T recommend it.
Latex-modified mortars must dry for the polymers to coalesce and form a hard...Read more
Why should I use the Schluter®-Shower System?
The Schluter®-Shower System is an integrated family of products that together form a fully bonded, watertight assembly for tiled showers...Read more
Can I use Schluter®-KERDI in my steam shower?
Yes. KERDI is suitable for use in intermittent use steam showers. Schluter®-KERDI-DS is required for continuous use steam rooms...Read more
What type of thin-set mortar should I use when installing Schluter®-KERDI?
The type of bonding mortar used to apply KERDI must be suitable for the substrate and must penetrate and engage the membrane fleece...Read more
What type of thin-set mortar should I use when installing ceramic and stone tile over Schluter®-KERDI?
Schluter-Systems requires the use of Schluter SET™ , ALL-SET™ , FAST-SET™, or an unmodified thin-set mortar meeting...Read more
Can I use a premixed thin-set mortar to install Schluter®-KERDI and tile in my shower?
No. Schluter®-Systems does not recommend the use of premixed thin-set mortars (mastics/adhesives) in any KERDI installation.Read more
I accidentally poked a hole through the Schluter®-KERDI while installing the membrane. Do I need to start over or can I simply repair the hole?
Holes can typically be repaired by installing a patch of KERDI or Schluter™-KERDI-BAND with...Read more
What is a water test? How do I perform one on the Schluter®-Shower System?
A water test is a quality control check performed on any shower installation before setting tile. It consists of stopping...Read more
What is the proper thin-set mortar consistency for installation of Schluter®-KERDI/-KERDI-DS?
When installing KERDI/-KERDI-DS the unmodified thin-set mortar is mixed to a fairly fluid consistency, but still able to hold a notch...Read more
Does Schluter®-KERDI waterproofing membrane have a front/back to it?
No, the KERDI membrane does not have a front/back to it. One side of the membrane features printed gridlines...Read more
Can I install glass tile over Schluter®-KERDI?
Glass tiles are unique products and may require special consideration. Please call Schluter®-Systems...Read more
Can I install Schluter®-KERDI over drywall in my tiled shower?
Yes. Once you install KERDI over the drywall panels, they will be completely protected from the water and vapor in your tiled shower.Read more
I’m installing Schluter®-KERDI over drywall in my shower. Do I need to tape the joints between panels before installing the KERDI?
No. It is not necessary to tape the joints between drywall panels before installing KERDI. If you must tape...Read more
How do I receive a lifetime warranty?
Complete the following 3 steps...Read more
Schluter®-KERDI over Solid Backing for Walls
Scott McGillivray on Waterproofing Principles using Schluter®-Systems
How to Waterproof Connections to Fixed Building Elements
Find some existing tutorials and project documentation videos to learn how-to get the best out of our products - for more fun in your life, start now!Watch more videos / playlists
Drains / Shower DrainsSchluter®-KERDI-DRAIN
Shower & Tub KitsSchluter®-KERDI-SHOWER-KIT