Use and Care Guide

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UNCOUPLING MEMBRANES
tile, be set on DITRA with latex-modified thin-set
mortar?
Answer: In general, we DON’T recommend it.
Here’s why: Latex-modified mortars must 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 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 could be required before grouting if using
modified thin-set mortars between DITRA and
ceramic tile, including porcelain tile. If extended
cure times were not observed, the results could
be unpredictable.
Question: Can Schluter
®
-ALL-SET and
Schluter
®
-FAST-SET modified thin-set mortars
be used to set tile over Schluter boards and
membranes?
Answer: Yes. All Schluter
®
thin-set mortars,
including the ALL-SET and FAST-SET modified
varieties can be used to set tile over DITRA,
DITRA-HEAT, KERDI, KERDI-BOARD, etc. non
absorptive substrates.
Question: How is this possible?
Answer: The key is predictability. Schluter
Systems’ modified thin-set mortars have been
specifically formulated to set and gain strength
in a timeframe that fits typical installation
practice, even when sandwiched between
Schluter
®
membranes or boards and porcelain
tile. The proportions of cement, water-retention
agents, polymers, and other components in
the mixtures were balanced to ensure that
extended dry times are not required. This was
validated through both laboratory and practical
testing. Now, the installer can select from either
unmodified or modified thin-set mortar to install
tiles within our systems according to his or her
preference.
Question: Why did Schluter Systems change
its position on thin-set mortar?
Answer: We haven’t changed our position
on thin-set mortar use within our systems.
Developing our own setting materials has given
us the ability to guarantee consistently positive
results. And since we control the formulas, we
can be sure no changes will be made that have
a negative impact on setting times and strength
gain in these environments.
Question: Does this mean I can use other
manufacturers’ modified thin-set mortars to
install tile over Schluter boards and membranes?
Answer: No. Our position on thin-set mortar use
within our systems in general has not changed.
We have no control over the formulation of
other manufacturers’ products and therefore
cannot guarantee consistently positive results
with their modified thin-set mortars.
Question: Can I still use other manufacturers’
unmodified thin-set mortars to install tile over
Schluter boards and membranes?
Answer: Yes. We still warrant the use of
unmodified thin-set mortar meeting ANSI
A118.1 to install tile within our systems because
we have confidence in the performance of this
product category. This is based on the science
of cement hydration and years of positive
testing and field experience.
Please note, if Schluter
®
thin-set mortars are
used with Schluter membranes an extended
system warranty is available.
Additional Notes:
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 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.
Connection to Floor Drains
Schluter
®
-KERDI-DRAIN or Schluter
®
-KERDI-
LINE may be used to provide drainage in
DITRA or DITRA-XL applications. DITRA or
DITRA-XL are sealed to the fleece-laminated
KERDI-DRAIN bonding flange with a section of
KERDI membrane using Schluter SET
®
, Schluter
ALL-SET
®
, Schluter FAST-SET
®
, or unmodified
thin-set mortar. KERDI-FIX is used to seal the
section of KERDI to the stainless steel KERDI-
DRAIN bonding flange.
The KERDI waterproofing collar on KERDI-LINE
is sealed to DITRA or DITRA-XL using Schluter
SET
®
, Schluter ALL-SET
®
, Schluter FAST-SET
®
,
or unmodified thin-set mortar.
Industry standard guidelines referencing floor
drains with integrated bonding flanges include
method B422 in the TCNA Handbook for
Ceramic, Glass and Stone Tile Installation, and
method 326DR in the Terrazzo, Tile and Marble
Association of Canada (TTMAC) Specification
Guide 09 30 00 Tile Installation Manual.
Notes:
1) When KERDI-DRAIN or KERDI-LINE are
used in shower applications, walls must
be waterproofed up to the height of the
showerhead. Please refer to the Schluter
®
-
Shower System Installation Handbook for
complete details.
2) Various configurations of KERDI-DRAIN and
KERDI-LINE are listed by ICC-ES (Report
No. PMG-1204), UPC® (IGC 195), CSA
(B79), and NSF (as a special engineered
product meeting applicable requirements of
ASME A112.6.3).
3) DITRA, DITRA-XL and KERDI meet the
American National Standard for Load
Bearing, Bonded, Waterproof Membranes
for Thin-Set Ceramic Tile and Dimension
Stone Installations (ANSI A118.10), are
listed by cUPC®, and are evaluated by
ICC-ES (see Report Nos. ESR-2467 and
PMG-1204).
For copies of the above listings or report,
please contact Schluter
®
-Systems at
800-472-4588 (USA) or 800-667-8746
(Canada) or by e-mail at [e-mail].
Links to the listings and report can also be
accessed at www.schluter.com.
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