Specification

permanent protection for moisture-sensitive
substrates, such as gypsum concrete and
wood, used in heated floor applications.
The open rib structure of the DITRA and
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 TCNA
Handbook for
Ceramic, Glass and Stone 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 and 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 and 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 and
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 and 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 at 800-472-4588 (USA) or 800-
667-8746 (Canada) or by e-mail at info@
schluter.com. 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 and 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
DITRA and 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 and 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 and DITRA-XL
and ceramic tile, including porcelain tile,
drying takes place very slowly through the
open joints in the tile covering. [According
to the TCNA Handbook for Ceramic, Glass
and Stone 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 or 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:
25 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 or
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 and 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
UNCOUPLING MEMBRANES
4