Installation Guide
EXTERIOR APPLICATIONS — Exterior Concrete Floors, Patios, and Walkways 15
Every substrate presents unique challenges
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.
Schluter
®
-DITRA’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 to exterior applications.
DITRA 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 matting provides a route for any residual moisture in the substrate to escape. This is
especially important when installing tile over a young slab, concrete slabs subject to moisture migration, or a fresh mortar
bed.
Since DITRA is virtually incompressible within the tile assembly, the advantages of uncoupling are achieved without
sacrificing point load distribution capabilities.
Because DITRA is uniquely engineered to provide uncoupling, vapor management, and waterproofing, all of which are essential functions in
exterior environments, it provides a reliable installation system for ceramic and stone tile surface coverings in exterior applications.
Exterior Concrete Floors, Patios, and Walkways
D-EXT-C-TS-15
Ceramic or stone tile
Unmodified thin-set mortar
DITRA or DITRA-XL
uncoupling membrane
Unmodified
thin-set mortar
Concrete
Concrete subfloor
Areas of Application
over structurally sound and even exterior
concrete on grade where positive drainage
below slab is provided
young concrete (concrete cured less than
28 days)
post-tensioned or pre-stressed concrete
cracked concrete
Limitations
minimum 2" x 2" (50 mm x 50 mm) tile
for wood or concrete balconies and terraces,
see detail D-EXT-OS, page 16. Please
contact Schluter-Systems with any questions
any cracks in concrete subfloor must exhibit
in-plane movement only; thin-set tile
assemblies, including those incorporating
DITRA or DITRA-XL, cannot accommodate
differential vertical displacement
Requirements
slab to be structurally sound
slab/assembly must be sloped for complete
surface drainage
gravel bed or other means of drainage must
be provided below slab
slab to be free of waxy or oily films and curing
compounds (when present, mechanical
scarifying is necessary)
all seams in DITRA and DITRA-XL and floor/
wall transitions must be sealed with
Schluter
®
-KERDI-BAND using unmodified
thin-set mortar; see page 22
Substrate Preparation
sloping of the slab or assembly must be
done prior to installing DITRA and DITRA-XL
Movement Joints
DITRA and DITRA-XL do not eliminate the
need for movement joints, including perimeter
joints, within the tiled surface. Movement
joints must be installed in accordance with
industry standards and norms; see page 18
of this Handbook, TCNA EJ171, and TTMAC
301 MJ
concrete floors may incorporate various
movement joints; see page 19 of this
Handbook for guidelines on how to treat the
different types of joints (control/contraction
joints, expansion joints, etc.)
Setting and Grouting Materials
unmodified thin-set mortar – ANSI A118.1
grout – A118.6, A118.7
Setting and Grouting Specifications
tile – ANSI A108.5
grout – A108.10
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