Use and Care Manual
2
Schluter
®
-DITRA-HEAT
Material Properties and
Areas of Application
DITRA-HEAT is a polypropylene membrane
with a cut-back stud structure and an anchoring
fleece laminated to the underside. The thickness
of the mat, including the stud structure is
1/4" (5.5 mm). DITRA-HEAT-DUO is a
polypropylene membrane with a cut-back stud
structure and a thermal break anchoring fleece
laminated to the underside. The thickness of the
mat, including the stud structure and thermal
break fleece is 5/16" (8 mm). Polypropylene is
not UV-stable in the long term; the product must
not be stored in places with prolonged exposure
to direct sunlight.
The DITRA-HEAT and DITRA-HEAT-DUO
mattings do not rot and are inert, non-toxic,
and physiologically safe. The material is highly
resistant to solutions containing salts, acids, and
alkalis, as well as many organic solvents, alcohols,
and oils. Resistance to specific stresses
can be provided if concentration,
temperature, and exposure time are known.
DITRA-HEAT and DITRA-HEAT-DUO are
waterproof and minimize the transmission of
vapor.
Schluter
®
-DITRA-HEAT-DUO offers the same
functions as the Schluter
®
-DITRA-HEAT
membrane, but also features an integrated
thermal break in the form of a thicker bonding
fleece. The thermal break reduces impact sound
transmission through floor-ceiling assemblies,
reduces heat loss to the substrate, and improves
the floor warming response time at the standard
three stud cable spacing.
When tested according to ASTM E2179, an
assembly of DITRA-HEAT-DUO and 12" x 12"
porcelain tile installed and grouted with cement-
based setting materials produced an increase
in impact insulation class (ΔIIC) of 20 to a
concrete slab floor-ceiling assembly (Test Report
NGC 7016078). The same basic assembly
tested according to ASTM C627 reached a
classification of “Light” in accordance with the
“TCNA Handbook for Ceramic, Glass, and Stone
Tile Installation,” defined as suitable for “light
commercial use in office space, reception areas,
kitchens, and bathrooms” (Test Report TCNA-
455-15 Test #1).
In laboratory testing, DITRA-HEAT-DUO
reduced floor warming response time from 68°F
(20°C) to 78°F (25.5°C) by approximately 80%
(90 minutes) compared to DITRA-HEAT over
a concrete substrate. Wood substrates act
as insulators and typically do not pose the
same challenges as concrete substrates. In
the same laboratory testing, DITRA-HEAT-DUO
only reduced floor warming response time from
68°F (20°C) to 78°F (25.5°C) by approximately
20% (5 minutes) compared to DITRA-HEAT
over a plywood substrate. Schluter
®
-DITRA-
HEAT-E-HK heating cables were spaced at
three studs in all of the above tests. Results
above are based upon laboratory testing. Actual
results may vary depending on various factors,
including concrete substrate thickness, concrete
substrate temperature, room temperature, heat
losses, etc.
DITRA-HEAT and DITRA-HEAT-DUO have been
evaluated according to the "Standard Method
for the Testing and Evaluation of Volatile Organic
Chemical Emissions from Indoor Sources Using
Environmental Chambers, Version 1.1" for
California Specification 01350 and found to
comply with the VOC requirements. California
Specification 01350 is referenced by various
green building standards and rating systems.
DITRA-HEAT-E-HK are twisted pair heating
cables designed for integration with the DITRA-
HEAT and DITRA-HEAT-DUO uncoupling
membranes in interior floor warming applications.
The cables can be installed without returning
to the thermostat and produce virtually zero
electromagnetic fields.
DITRA-HEAT-E-WiFi/-RT/-R are digital
thermostats to control the DITRA-HEAT-E-HK
heating cables (either 120 V or 240 V). The
thermostats feature a built-in Class A ground
fault circuit interrupter (GFCI) with indicator light.
The DITRA-HEAT-E-WiFi programmable WiFi
thermostat features LCD touchscreen controls
and comes with a pre-set schedule, but may be
adjusted to fit any schedule. When connected
to WiFi, the thermostat provides convenient
monitoring and adjustment of the floor warming
system via the web or mobile app. The DITRA-
HEAT-E-RT programmable thermostat features
LCD touchscreen controls and comes with
a pre-set schedule, but may be adjusted to
fit any schedule. The DITRA-HEAT-E-R non-
programmable version features a simple on/
off function. Multiple heating cables may be
connected to the thermostats, up to the total
heating load limit of 15 amps. The DITRA-HEAT-
E-RR power module may be used in conjunction
with the DITRA-HEAT-E-RT/-R thermostats
when the heating load exceeds 15 amps (e.g.,
in large floor applications). A floor temperature
sensor is included.
Two floor temperature sensors are provided
– one with the DITRA-HEAT-E-WiFi/-RT/-R
thermostats and one with the DITRA-HEAT-
E-HK heating cables. Both floor temperature
sensors are installed within the tile assembly. One
sensor is connected to the thermostat, while the
other sensor is stored in the thermostat electrical
box, but not connected to the thermostat. The
second sensor can easily be connected to the
thermostat to replace the first sensor in case of
damage.
Suitable Substrates
Wood
All wood materials, including OSB, plywood,
and framing members, are subject to expansion,
contraction, bending, and deflection as a result
of changes in moisture content and loading.
Further, these deformations fluctuate over the life
of the building structure.
Concrete
There are various challenges associated with
the installation of hard surface coverings on
concrete substrates. To begin, the coefficient of
thermal expansion of concrete is close to twice
that of ceramic tile. Additionally, tile contractors
are often expected to install tile over young
concrete (concrete cured less than 28 days).
However, rigid surface coverings installed
over young concrete are susceptible
to damage as a result of shrinkage during
curing. Pre-stressed/post-tensioned
concrete slabs are also commonplace
in today’s construction environment.
Although pre-stressing is used to help control
deflections in concrete structures, these slabs are
still subject to deformations caused by changes
in moisture, temperature, and loading. Many
concrete slabs on or below grade are subject to
moisture migration, which can be problematic.
Furthermore, these structures experience the
same deformations as stated above.
Gypsum
Bonding ceramic or stone tiles directly
to gypsum concrete substrates is generally
considered questionable or not recommended.
The challenges associated with gypsum-based
underlayments include the requirement of an
extended drying period before installing tile and
continued sensitivity to the reintroduction of
moisture throughout the life of the installation.
In addition, since the coefficient of thermal
expansion of gypsum concrete is substantially
greater than that of ceramic tile, shear stresses
caused by temperature fluctuations can result
in delamination or cracking of the tile covering.
Note: DITRA-HEAT and DITRA-HEAT-DUO may
be installed over existing vinyl floors (no cushioned
or perimeter bonded vinyl). However, various
steps must be taken to ensure a successful
installation. Please refer to the Schluter
®
-DITRA-
HEAT Installation Handbook for details.
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-HEAT Installation Handbook.
To download a PDF version of the handbook or
to view the installation video online, please visit
www.schluter.com.
All substrates must be clean, even, and load
bearing. Bond inhibiting surfaces must be
removed prior to the application of DITRA-HEAT
and DITRA-HEAT-DUO.