Installation Guide

14 EXTERIOR APPLICATIONS — Exterior Systems Planning Guide
Exterior Systems Planning Guide
A successful installation involves proper planning and following the appropriate exterior detail found in the Schluter
®
-DITRA Installation
Handbook. This checklist is designed to help you evaluate the conditions when planning an exterior tile assembly. If all items listed
cannot be satisfied, there is risk of assembly failure and no warranty will be provided. In that case, we recommend not
proceeding with the project.
q Ensure suitability of the balcony structure
The structure must be able to support the weight of the proposed tile assembly. The typical weight of an exterior tile assembly with a 1-1/2" (38 mm) -thick
mortar bed weighs 24 pounds/square foot according to the TCNA Handbook for Ceramic, Glass, and Stone Tile Installation. This will vary depending on
materials selected for your particular installation. The owner should work with a design professional (e.g., engineer, architect, etc.) to ensure the structure
is suitable for the intended use and complies with applicable building codes.
q Ensure adequate room for proper installation
The structure must allow for the height of the installed tile assembly. Provide adequate room to ensure the installer can create or maintain slope away from
the building, which will allow for the installation of roofing membrane flashing, particularly at door openings. Additionally, sufficient elevation drop from the
interior to exterior at door thresholds is recommended to keep water from entering the building.
q Ensure moisture management throughout the assembly
q Sufficient slope (1.5 – 2.0%).
q Protect the balcony structure with a roofing membrane. Membrane installation to be completed by roofing professional. Schluter
®
-Systems
does not supply roofing membranes or warranty structural waterproofing in exterior applications.
q Appropriate flashing must be installed where required and all protrusions must be sealed.
q Include a drainage membrane (e.g., TROBA or TROBA-PLUS) in assemblies with mortar beds.
q Water must be directed away from the structure including the use of flashing and a drip edge (e.g., BARA) at the perimeter of the
assembly. A gutter system (e.g., BARIN) installed with edging profiles is the most complete solution. This combination provides
edge finishing and water management at balcony and terrace perimeters. When parapet walls are surrounding the assembly, a floor
drain may be used. Considerations of drain installation should be taken into account during design of the assembly.
q Ensure full thin-set mortar coverage during tile installation
ANSI A108.5 requires 95% contact area between tiles and thin-set mortar in exterior applications. The coverage must be distributed to give full support
to the tile with particular attention to the corners. Back-buttering is a useful way to help ensure proper coverage, particularly when installing large-format
tiles. By back-buttering, it is possible to fill in the concave area on the back of the tile (ceramic tiles are not perfectly flat) and improve contact with the
mortar combed on the substrate. Combing the mortar in one direction can also improve coverage by making it easier to collapse the mortar ridges when
embedding the tiles.
q Ensure installation of movement joints
DITRA does not eliminate the need for movement joints, which are essential in any installation. Provide perimeter joints at all restraining surfaces (e.g., walls,
railings, etc.). In exterior applications surface movement joints must be placed every 8' - 12' (2.4 m – 3.7 m) in each direction.
q Ensure appropriate railing design and installation
It is recommended to choose under- or side-mounted railing systems when practical to avoid roofing membrane penetration. While not recommended, if
a top-mounted railing system is the only option available, care must be taken to ensure that protrusions through the waterproofing layer(s) are sealed by
the roofing professional.
q Materials Selection
q Exterior applications have the potential for surface water, which may create slippery surfaces. Therefore, consider the slip resistance
of the tile and select a material recommended by the manufacturer for the intended use. It is recommended that tiles are
tested according to the ANSI A137.1 DCOF AcuTest method to evaluate Dynamic Coefficient of Friction. Please refer to the TCNA
Handbook for Ceramic, Glass, and Stone Tile Installation for further information.
q For assemblies exposed to freeze-thaw conditions, the tile must be frost-resistant and recommended by the tile manufacturer for the
intended use. It is recommended that the tiles are tested according to the ASTM C1026 Standard Test Method for Measuring the
Resistance of Ceramic and Glass Tile to Freeze-Thaw Cycling.
q When selecting profiles, use color-coated aluminum, PVC, or stainless steel. When stainless steel profiles are exposed to de-icing salts,
use stainless steel 316L (1.4404 = V4A).
q Respect exterior working conditions
Working in exterior environments involves considerations during installation and curing of the tile assembly. Observe temperature ranges required by the
setting material manufacturer during both installation and curing. Tenting of working area may be necessary to shade the surfaces from direct sunlight
and/or rain. Direct sun or high temperatures may cause issues such as flash setting or skinning of the mortar. If an installation is to be completed in cold
temperatures, heat will be required in the space before, during and after installation to ensure proper curing of the mortar. Combustion heaters must be
vented for carbon monoxide safety.
If acceptable working conditions cannot be maintained, stop the installation.
Lastly, efflorescence is considered to be a natural occurrence with cementitious materials and is therefore not to be considered a defective condition. Since
exterior tile assemblies are installed with cementitious thin-set mortars and grouts and exposed to water, there is always the possibility of efflorescence.