Installation Guide

PRODUCT SELECTION — Choosing between Schluter
®
-DITRA and DITRA-XL 5
DITRA
DITRA-XL
Even Transitions to Hardwood Flooring
In many thin-set ceramic tile applications, one of the goals is to minimize the thickness
of the assembly to reduce height transitions from the tile to other floor coverings such
as carpet, engineered wood, or vinyl. At 1/8" (3 mm)-thick, DITRA accomplishes this
goal while providing the four essential functions for successful tile installations. Schluter
floor profiles finish and protect tile edges at these transitions to complete the installation.
However, where ceramic tile meets 3/4" (19 mm)-thick hardwood, minimizing the
thickness of the tile assembly can result in a height transition up to the hardwood.
On various projects, our customers began using two layers of DITRA to solve this
problem. From a technical perspective this was a sound approach because DITRA
is configured to provide load distribution and is virtually incompressible within the tile
assembly. These customers felt that using two layers of DITRA was reasonable on
relatively small applications, as the benefit outweighed the additional labor in their
perspective. However, they requested a better solution.
Research and Development
Since the uncoupling function is based on the geometric configuration of the product,
we recognized that increasing the thickness of DITRA would result in increased
movement accommodation. When the new product was tested, it became clear
that the increase was significant. Specimens including porcelain tile set on DITRA-XL
over single layer 3/4" (19 mm)-thick plywood subfloors with joists spaced at
24" (610 mm) o.c. were tested according to the ASTM C627 “Standard Test Method
for Evaluating Ceramic Floor Tile Installation Systems Using the Robinson Type Floor
Tester.” The two assemblies produced ratings of Heavy and Extra Heavy per the TCNA
Handbook for Ceramic, Glass, and Stone Tile Installation. Test results are summarized
in the table below.
Test Setup
1. 2" x 2" joists
2. APA-rated “Exposure 1” tongue-and-groove plywood subfloor; 23/32"
(3/4" nom.) thickness
3. Latex portland cement mortar (ANSI A118.11)
4. DITRA-XL
5. Unmodified thin-set mortar (ANSI A118.1)
6. Tile
7. Polymer-modified cement grout (ANSI A118.7)
Joist Spacing Tile ASTM C627 Test Rating
TCNA Test
Report Number
24"
12" x 12" porcelain;
5/16" nominal thickness
Heavy (12 cycles) TCNA-303-06
24"
6" x 6" porcelain;
5/16" nominal thickness
Extra Heavy (14 cycles) TCNA-153-09