Raised Access Floors are a common installation system in commercial applications. They allow
for voided floor space underneath the finished floor to distribute power, air, data and voice.
It is common to have multiple finished floor surfaces installed over the top of the panels.
Tile is a popular choice for such applications due to its durability, ease of maintenance
and beautiful finish. Typically, plywood or cement board is installed
with appropriate setting materials over the panels, followed by tile.
However, these substrates can be cumbersome to work with and are difficult to bond directly
to the various panel materials. Not to mention they can also be costly and often have no
warranty. Panels are available in a variety of surface
materials with the most common being concrete, galvanized steel and resin coated steel.
Why choose DITRA for a Raised Access Floor?
DITRA is specifically designed to allow the installation of ceramic and stone tile over
any even and load bearing substrate---including the various panel substrates in raised access
flooring systems! DITRA is also lightweight and quick and easy
to install.
DITRA is thin which minimizes tile assembly thickness and reduces transitions to lower
surface coverings
These characteristics make tile installation over larger commercial spaces efficient.
DITRA performs four essential functions…..
The first function is uncoupling. This allows the tile and substrate to move independently
of one another and helps to prevent cracked tile and grout.
Waterproofing…and vapor management…can help keep all of those under floor elements
safe from water and residual moisture.
…and support… to make sure that the tile covering will remain intact when exposed to
heavy traffic.
All of these functions make DITRA the reliable choice over raised access floor systems.
This video will show you how to install DITRA over Raised Access Floor Panels.
Refer to the Schluter®-DITRA Installation Handbook detail D (DASH) AFP (DASH) T for
all of the requirements for installation and for comprehensive warranty information.
You will also find testing information on this application.
We have also chosen to install a KERDI-DRAIN as a secondary floor drain within the assembly.
The KERDI-DRAIN can be installed in wet areas where waterproofing is desired (required)
such as washrooms, janitorial rooms, and kitchens. The subfloor panels are properly fastened
to the appropriate pedestals and secure and any leveling that was required beforehand
has been completed. The opening in the panels for the KERDI-DRAIN
has been prepared. Sweep the floor to remove any debris and clean
any dust from the substrate with a damp sponge. Galvanized steel surfaces in particular need
to be cleaned to remove any grease or other contaminants.
The substrate is clean, even and load bearing. First, we need to apply a thin-set mortar
primer to the panels. Use a primer that is suitable for the application.
Consult the primer manufacturer for application instructions and drying times.
Acceptable panels must feature a surface that can be prepared to bond with thin-set mortar
and hold the weight of the tile assembly. Once the primer is dry, we install the DITRA
membrane.
DITRA is installed simply and easily with thin-set mortar.
We are using Schluter ALL-SET modified thin-set mortar to bond the matting to the primed panels.
Schluter FAST-SET rapid-setting modified thin-set mortar may be used as well.
If you are not using a Schluter® mortar, a modified thin-set mortar is used to install
DITRA over primed access panels..
The mortar is mixed to a fairly fluid consistency, but still able to hold a notch.
A one-quarter inch by three-sixteenths inch V-notched trowel or the Schluter-DITRA-TROWEL,
which features a four-point-five millimeter by four-point-five millimeter square-notched
design, is used to apply the mortar.
Apply a thin layer of the mortar with the flat side of the trowel to produce solid contact
with the substrate and then comb additional mortar using the notched side of the trowel.
Apply the DITRA, fleece side down,
…and solidly embed in the mortar using a float or the DITRA-ROLLER.
When using the DITRA-ROLLER, place a weight on the shelf and slowly move the roller from
one end of the matting to the other, slightly overlapping successive passes.
Bags of thin-set mortar, grout or boxes of tile can be used as weight, provided the total
weight is kept under seventy-five pounds.
Lift up a corner of the membrane to check coverage. Proper installation results in full
contact between the fleece and the thin-set mortar.
Re-embed the DITRA.
If sufficient coverage is not achieved, remove and reapply fresh mortar.
This process is repeated over the entire floor, abutting adjacent pieces of DITRA, until the
installation is complete.
In dry areas, tile can now be installed. In this particular application, waterproofing
is required so a floor drain is being installed within the assembly.
We are installing the stainless steel KERDI-DRAIN.
Mark the DITRA around the drain flange. Cut and remove the membrane. This will allow the
KERDI-DRAIN to sit flush or slightly below the DITRA.
The KERDI-DRAIN is installed with thin-set mortar.
Apply thin-set mortar to the area where the KERDI-DRAIN is to be installed.
Schluter®-ALL-SET or FAST-SET thin-set mortar can be used.
Press the KERDI-DRAIN firmly into the mortar to ensure full support of the bonding flange
and see that it is flush or slightly below the DITRA.
Check for level.
Floors can be made fully waterproof with DITRA if desired by sealing drain connections, floor-to-wall
transitions, and seams with Schluter-KERDI waterproofing accessories.
A section of KERDI is used to secure the connection to the KERDI-DRAIN.
Measure and cut a section of KERDI so that a 2 inch overlap is achieved at all junctions.
The stainless steel KERDI-DRAIN requires the use of Schluter®-KERDI-FIX to bond the KERDI
to the flange. A small tube of KERDI-FIX is included with the Stainless Steel drain flange..
The Stainless Steel flange must be clean and free of grease or other contaminants prior
to applying KERDI-FIX. Apply KERDI-FIX to the drain flange.
Then apply any of our Schluter® Thin-set Mortars…. or an unmodified thin-set mortar
to the DITRA surrounding the flange.
The mortar is mixed to a fairly fluid consistency, but still able to hold a notch.
A one-quarter inch by three-sixteenth inch V-notched trowel or the Schluter-KERDI-TROWEL,
which features a one-eighth inch by one-eighth inch square-notched design, is used to apply
the mortar.
Apply thin-set mortar to the area where the KERDI is to be installed.
Fill the cavities in the DITRA matting and comb additional mortar using the notched side
of the trowel.
Embed the KERDI into the thin-set mortar using the flat side of the trowel or a dry wall
finishing knife.
Repeat this process around the entire drain making sure this connection is secure.
Clean any excess setting material from the step in the bonding flange. We used baby wipes
for this.
To complete the waterproofing application, KERDI-KERECK corners and the KERDI-BAND are
installed along the floor to wall transitions and DITRA seams.
The process for installation is the same. Two inch overlaps can be achieved at inside
corners without continuing KERDI-BAND all the way to the corner of the room. This will
limit build-up of the membrane in these areas and make setting small tiles easier.
Finally, KERDI-BAND is installed at DITRA seams.
The waterproofing application is now complete. Tile may be installed immediately over DITRA
using any of our Schluter® thin-set mortars, or an unmodified thin-set mortar.
Fill the cavities in the DITRA with thin-set mortar. Then comb additional mortar over the
matting using a notched trowel that is appropriate for the size of the tile.
It is best practice to back butter the tile.
Solidly embed the tiles in the setting material, making sure to observe the open time of the
mortar. Slide the tile back and forth to collapse the mortar ridges and transfer the mortar
to the back of the tile.
It is important to have a perimeter movement joint throughout the tile assembly.
One option, as shown here, is to use shims to keep a ¼” area between the wall and
tile free of any setting material to ensure a consistent joint along the perimeter.
We’ll continue to clean this area as we set our tile and will remove the shims once
the installation is complete so that we have a functional movement joint between the tile
assembly and the wall Continue to set the tile up to where the KERDI-DRAIN
Grate will be installed. The grate assembly is installed in conjunction
with the tile.
Be sure to back-butter the underside of the grate to help ensure full support.
Then place the height adjustment collar inside the lateral adjustment ring.
Fill the step in the bonding flange with thin-set mortar.
Press the assembly into the mortar and install the surrounding tiles, ensuring full coverage.
Position the grate to match the joint pattern of the tile covering and press flush with
the tile surface.
Remove all excess setting material immediately. Continue setting the tile up to where the
transition profile will be installed. We are installing the Schluter-RENO-U to transition
from the tile floor to the carpet.
Using a notched trowel, apply thin-set mortar to the area where the RENO-U profiles will
be installed.
Fill the cavity beneath the sloped section of the profile with thin-set mortar.
We are abutting the profile up to the DITRA membrane. By keeping the anchoring leg free
of DITRA, it will also help eliminate any build up when installing tile.
Firmly press the anchoring leg of the profile into the thin-set mortar and align.
Apply additional thin-set mortar over the anchoring leg of the RENO-U and set tile as
usual. Grout is applied to complete the tile installation.
Keep in mind, it is important to keep the perimeter of the tile installation clean so
that we do not compromise that free space serving as our movement joint.
We decided to install the DESIGNBASE-SL-E wall base profile since it offers the perfect
alternative to rubber or vinyl wall bases in commercial applications.
DITRA is the perfect solution to set tile in raised access flooring applications. The
benefits and ease of installation help to ensure consistent success over the various
types of panels and allow tile to be integrated into these systems to provide a beautiful
and durable finish!