How to Install a Schluter Shower System

Stone and ceramic tiles are hygienic, easy to maintain and durable, making for the ideal surface coverings especially in wet areas, such as bathtub surrounds and showers. However, these tiles are not are not usually waterproof and thus be installed with a waterproofing system that can effectively protect building materials from moisture and control mold growth.

The Schluter shower system is comprised of multiple products integrated together to create a sealed system. It includes the KERDI drain that should be installed with either the Schluter-KERDI prefabricated foam tray or a sloped mortar bed to provide a secure connection to the Schluter-KERDI waterproofing membrane at the top of the assembly through a unique integrated bonding flange. With all components in place, the final assembly offers superior moisture management, preventing moisture to penetrate into the solid backing or mortar bed, allowing the entire assembly to dry completely in between uses. All in all, the integrated Schluter shower system eliminates leaks and prevents mold growth and potential efflorescence in the bath system. It is also designed to make shower installation easier and dramatically reduce total installation time.

With all the necessary tools and materials in hand, here are the steps to take to install a Schluter shower system:

1. Locate the right position for your drain and then cut a hole (limit diameter to 125 millimeters) in the substrate using as a template the KERDI SHOWER-ST tray. Remember that a bigger hole can cause lack of support and eventually damage to the tile assembly, such as cracked grout around the drain. Using the dry-pack mortar, fill in the box-outs in your concrete floor and then use a 100mm diameter plastic pipe coupling or something similar to use as a form around the waist line, making sure that it accommodates the KERDI-DRAIN bonding flange.

2. Apply the unmodified thin-set mortar to the substrate using a 6mm x 10mm U-notched or square trowel. Making sure that the floor is level, place the KERDI shower tray and embed it solidly in the mortar. You can cut the tray to certain sizes to fit various applications, but make sure you cut it by equal amounts on all its sides to ensure a uniform height of the first course of the wall tiles. You can also extend the shower base past the perimeter of the shower tray with the use of the dry-pack mortar. Remember that before you install the tray, you should apply a thin-set mortar to the substrate, as well as to the top and bottom of the detached center section. It is also recommended to install the tray before setting the drain, as this allows greater control over the final position of the drain, making it easier to achieve full support under the bonding flange.

3. Check the tray’s underside to ensure that full support and coverage is achieved. In using the KERDI shower bench, apply unmodified thin-set mortar to your floor and walls with the use of a 6mm x 10mm U-notched or square trowel. Now, embed the bench solidly in the mortar by checking the back and undersides of the bench to ensure full support and coverage.

4. Create the tray-to-wall and wall-to-ceiling connections and make sure you seal the vertical inside corners with the 125mm-wide cut sections of the KERDI waterproofing membrane or the KERDIBAND waterproofing strip. Then, install the KERDI-KERECK-F pre-formed corners at the inside corners, which is especially important when installing KERDI on the ceiling.

5. Protect your walls and ceiling from vapor penetration and moisture by constructing seams by overlapping the edges of KERDI by at least 50 millimeters or by butting adjacent sheets of KERDI and then installing the KERDI-BAND, centering over the joint. Again, this is important when installing KERDI on your ceiling.

6. Install the KERDI pipe seals at the body spray, showerhead and the other shower components, and then the specialized KERDI seal at the mixing valve. As alternative, you can use the KERDI-FIX or a similar type of sealant to seal protrusions in pipes or protect the solid backing panels at the mixing valve from moisture.

7. Install the KERDI drain by pressing it firmly into the mortar to ensure full support of the bonding flange. When setting the drain prior to the shower tray, the drain should be connected to the waste line and positioned to the right height with the use of the tray’s detachable center section or the foam spacers that come with the drain.

8. Find access to the plumbing from below and then connect the waste line after installing the drain. Apply the unmodified thin-set mortar to the entire surface of the shower tray and then completely fill the step in it. When using PVC or ABS drain, apply additional mortar on to the top of the fleece-laminated bonding flange. If you are using one made of stainless steel, it is adhered to the bonding flange with the use of the KERDI-FIX sealant or adhesive. Make sure the steel bonding flange is clean and free of contaminants, such as grease, before applying the sealant.

9. Embed the KERDI waterproofing membrane into the mortar and set the matting on to the tray’s entire surface to remove air pockets and ensure proper adhesion. If necessary, cut the KERDI shower curb to the appropriate length with a handsaw. Apply unmodified mortar to the edge of the shower tray, floor and walls using the trowel, and then press the curb firmly into place. Check the curb’s underside to achieve full support and coverage.

10. Seal the shower curb and the bench to the tray and walls using the KERDI pre-formed inside and outside corners. Seal the junctions of the curb and bench to the tray with KERDI-BAND.

11. Wait about a day before you perform water testing and proceed to the final application of mortar to complete KERDI waterproofing applications, ensuring the connections and seams are sealed

12. When installing the tiles, make sure the tray and the KERDI applications are protected in an appropriate manner, like laying cardboard over the floor to prevent damage. Using the right trowel for your tile size, apply unmodified mortar directly to the exposed surface of KERDI applications, and then install the tiles, ensuring full coverage. The grate assembly is also installed in conjunction with the tiles.

More Information

It is also possible that your Schluter shower system comes with a stock mortar base. In this case, the installation steps are virtually similar to the ones presented above, with just minor changes.

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