The comfort of warm floors can bring a touch of luxury to any room in the home. That luxury can
now extend right in to your tiled shower. DITRA-HEAT is an electric floor warming system
with integrated uncoupling technology to ensure that floors are both comfortable and resistant
to cracked tiles and grout. Cables can be placed wherever
heat is desired—even in your tiled shower! We’re going to show you the basics of how to
install it in a shower application. Before starting, always refer to the
Schluter-Systems DITRA-HEAT and Shower System Installation Handbooks.
The handbooks provide you with all of the information needed
to install DITRA-HEAT in a shower. Approval of electric floor warming in
shower applications must be verified by the local building code official
or authority having jurisdiction. In our demonstration, we will be
installing the KERDI-LINE linear drain. Prepare the KERDI-SHOWER-LS shower tray by
removing the flat section in order to ensure proper slope all the way to the drain.
The height of your drain flange is the first consideration when
preparing for the installation. Because the DITRA-HEAT membrane will
be installed on top of the shower tray, we have to raise the drain flange accordingly.
We will do this by installing DITRA-HEAT on the substrate under the KERDI-LINE channel
body support. This will raise
the drain flange to the correct elevation. The same idea applies when using the KERDI-DRAIN.
Install the membrane under the detachable center section of the KERDI-SHOWER-ST
shower tray and then install the drain flange. Let’s get to work and start our installation.
Use the channel body support as a guide to cut a piece of the DITRA-HEAT membrane. Don’t forget
to include an opening for the drain outlet. We will be using Schluter ALL-SET thin-set
mortar throughout this demonstration. In this application, any Schluter mortar,
or other manufacturer’s unmodified thin-set mortar , can be used.
Apply thin-set mortar to the area where the cut section of DITRA-HEAT will be installed with a
DITRA-HEAT trowel. Or you can use a one quarter inch by one quarter inch square notched trowel.
Solidly embed the membrane into the thin-set mortar.
Apply thin-set mortar on top of the DITRA-HEAT membrane.
Install the KERDI-LINE channel body support. Then, install the KERDI-LINE drain flange
using the same mortar and trowel. Always make sure your drain is level.
Install the shower tray with thin-set mortar applied using a one-quarter inch by three-eighths
inch square- or U-notched trowel. Next, install the DITRA-HEAT membrane
over the shower tray with thin-set mortar and the DITRA-HEAT trowel.
Now let’s talk about the heating cables…. Always test your cables before and after
installation into the matting, and again after tiling.
We’ve chosen to begin the heating cable installation where we want our cable to end.
This is the easiest and most efficient way to do the layout in the shower.
Since we are using KERDI-LINE, the cable is spaced three studs from the edge of the drain flange.
If you are using KERDI-DRAIN, two stud spacing is required from the edge of the flange.
Note that the cable layout may take a few tries to get as desired. This
is normal and easy to do with DITRA-HEAT. Always take care to plan your heating cable layout
carefully as the cable cannot be cut to length. We recommend using a dedicated heating cable
inside the shower area and a separate cable over the bathroom floor.
If the shower heating cable is damaged in the future,
it can easily be disconnected from the thermostat without compromising the bathroom floor warming.
Once the cable is installed over the shower base, dry fit the shower curbs.
Note that the heating cable should be run about halfway around the stud adjacent to the curb
before turning up the curb to exit the shower. This helps increase the bending radius and
minimizes stress on the cable. Mark the curb where the
cable will be installed. Cut a three-quarter inch wide by one-quarter
inch deep groove into the curb. We used a router to produce a nice, clean cut, but you can use
other tools for the job, such as a table saw or circular saw, or even a utility knife.
It is important to do this before installing the curb because we won’t
be able to cut it once is installed. Install the shower curbs with thin-set
mortar applied using a one-quarter inch by three-eighths inch notched trowel.
Keep in mind, that the heating cables CANNOT be installed under or through
the curb. This could cause overheating and damage the heating cable and the curb.
The floor temperature sensor should not be installed inside the shower area, rather on the
bathroom floor. This will prevent the thermostat from turning off the bathroom floor warming cable
prematurely when the shower is in use. Also, the heating cable hot-to-cold
splice should not be installed in the shower. Before finishing our heating cable installation,
we need to install DITRA-HEAT over the bathroom floor since the shower
heating cable has to connect to the thermostat. Use a hot glue gun or similar to secure the cable
into the groove previously cut in the curb. You can fill the groove with thin-set mortar
now or when waterproofing the shower base. Install the remainder of the shower heating cable
and connect the cold lead to the thermostat. Now that we have finished installing our shower
heating cable, we will begin installation of the heating cable for the bathroom floor.
We are starting six inches from the wall to create a buffer zone.
This area allows for the placement of excess heating cable since it is difficult to
predict exactly where the cable will end. Next, let’s waterproof the shower base.
Install the Schluter-KERDI waterproofing membrane over the DITRA-HEAT system on
the shower base with thin-set mortar. The KERDI collar on the KERDI-LINE drain
is connected to the shower base and walls. Next, we use thin-set mortar to fill
the groove in the curb and fully encapsulate the heating cable.
Seal this area with KERDI-BAND. Complete the waterproofing with
KERDI-KERECK corners and KERDI-BAND making sure that all seams are
covered with a two inch overlap, as required. This completes the waterproofing in the shower.
Finally, we will connect the heating cables and temperature sensors to the thermostat.
The installation of the DITRA-HEAT system in the shower is now complete.
For comprehensive installation requirements and instructions, refer to our installation
handbooks and watch our DITRA-HEAT and Shower System Installation videos!
Now, DITRA-HEAT provides the luxury of heated tile floors even in the shower!