Schluter-DITRA Technical Data Sheet

The open rib structure of the DITRA/
DITRA-XL matting allows the residual
moisture in the substrate to escape.
This is particularly important for gypsum
concrete since it must dry in order to
gain strength. In addition, the free space
beneath the matting limits thermal striping
by promoting even heat distribution
throughout the assembly.
Industry standard guidelines referencing
uncoupling membranes over heated floors
in
clude methods RH111, RH112, RH122 and
RH123 in the TCA
Handbook for Ceramic
Tile Installation and method 314F (Details
A, B, C, D, E and F) in the Terrazzo, Tile
and Marble Association of Canada (TTMAC)
Specification Guide 09 30 00 Tile Installation
Manual.
Exterior Applications
Ceramic and stone tiles are ideal surface
coverings for the exterior and have been
used successfully for thousands of years.
Exterior balconies and terraces are ideal
opportunities for the installation of tiled
surfaces. However, these installations have
typically presented significant challenges to
tile setters. Since hard surface coverings are
rigid by nature and have different physical
properties compared to virtually every
substrate, they cannot be bonded directly
to the substrate, particularly in exterior
applications where they are exposed to
potentially severe climatic changes and the
recurring introduction of moisture.
DITRA/DITRA-XL’s uncoupling function
protects the ceramic or stone tile covering
by neutralizing the differential movement
stresses between the substrate and the tile,
thus eliminating the major cause of cracking
and delaminating of the tiled surface. This
is particularly important since these stresses
are magnified by the significant temperature
gradients common in exterior applications.
DITRA/DITRA-XL provides effective
waterproofing that will protect the tile
assembly from the recurring introduction
of water which is common in exterior
applications.
The free space beneath the
DITRA/DITRA-XL
matting provides a route for any residual
moisture in the substrate to escape. This is
especially important when installing tile over
a young slab, a concrete slab subject to
moisture migration, or a fresh mortar bed.
Since DITRA/DITRA-XL is virtually
incompressible within the tile assembly,
the advantages of uncoupling are achieved
without sacrificing point load distribution
capabilities.
Installation
For complete installation guidelines and
warranty criteria, please contact Schluter-
Systems (USA: 800-472-4588; Canada:
800-667-8746) to receive a copy of
the Schluter
®
-DITRA Installation Handbook
and a step-by-step installation video. To
download a PDF version of the Handbook
or to view the installation video online,
please visit www.schluter.com.
Thin-set Facts
Question: Can ceramic tile, including
porcelain tile, be set on DITRA/DITRA-XL
with unmodified thin-set mortar?
Answer: YES. In fact, we recommend it.
Here’s why: Portland cement-based
unmodified thin-set mortars are dependent
upon the presence of moisture for hydration
in order to gain strength. Since Schluter
®
-DITRA/DITRA-XL is impervious, it does
not deprive the mortar of its moisture. This
allows the cement to properly hydrate,
resulting in a strong, dense bond coat.
In fact, after the mortar has reached final
set (usually within 24 hours), unmodified
thin-set mortars achieve higher strengths
when cured in continually moist conditions.
Question: Can ceramic tile, including
porcelain tile, be set on DITRA/DITRA-XL
with latex-modified thin-set mortar?
Answer: We DON’T recommend it.
Here’s why: Latex-modified mortars must
air dry for the polymers to coalesce and
form a hard film in order to gain strength.
When sandwiched between two impervious
materials such as DITRA/DITRA-XL and
ceramic tile, including porcelain tile, drying
takes place very slowly through the open
joints in the tile covering. [According to the
TCA Handbook for Ceramic Tile Installation,
this drying period can fluctuate from 14
days to over 60 days, depending on the
geographic location, the climatic conditions,
and whether the installation is interior or
exterior]. Therefore, extended cure times
would be required before grouting if
using modified thin-set mortars between
DITRA/DITRA-XL and ceramic tile, including
porcelain tile. If extended cure times
were not observed, the results could be
unpredictable. This is even more important
to consider in exterior applications that are
exposed to rain, as there is the additional
concern of latex leaching.
Additional Notes:
15 years of field experience and testing
by the Tile Council of North America
(TCNA) support the efficacy of using
unmodified thin-set mortars to bond
ceramic tile, including porcelain tile, to
DITRA/DITRA-XL in both interior and
exterior applications. Remember, the
type of mortar used to apply DITRA/
DITRA-XL depends on the type of
substrate. The mortar must bond to the
substrate and mechanically anchor the
fleece on the underside of the matting.
For example, bonding DITRA/DITRA-XL
to wood requires latex-modified thin-set
mortar. Additionally, all mortars (modified
and unmodified) have an acceptable
temperature range that must be observed
during application and curing.
Movement Joints
DITRA and DITRA-XL do not eliminate the
need for movement joints, including perimeter
joints, within the tiled surface. Please refer to
the Schluter
®
-DITRA Installation Handbook
for movement joint placement guidelines.
Wood Underlayment
In some applications, adding a layer
of plywood or OSB before installing
DITRA or DITRA-XL and the ceramic
or stone tile covering is required to
reduce deflection and curvature of the
sheathing between the joists. Please
refer to the Schluter
®
-DITRA Installation
Handbook for plywood/OSB underlayment
installation guidelines.
UNCOUPLING MEMBRANES
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