DITRA-HEAT Installation Guide

4 WOOD — Floors, Interior - Ceramic or Porcelain Tile
Every substrate presents unique challenges
WOOD
Floors, Interior - Ceramic or Porcelain Tile
DH-W16-T-19
16" (406 mm) o.c. joist spacing, single layer OSB
or plywood subfloor
Areas of Application
over any even and structurally sound OSB or
plywood subfloor with 16" (406 mm) o.c. joist
spacing
interior dry or wet areas
Limitations
minimum 2" x 2" (50 mm x 50 mm) tile
for natural stone, see detail DH-W-S (page 6)
and natural stone discussion (page 33)
Requirements
maximum spacing of joists, I-joists, or floor
trusses is 16" (406 mm) o.c.
minimum subfloor thickness – 19/32", 5/8"
nom. (16 mm) tongue-and-groove with 1/8"
(3 mm) gap between sheets.
Substrate Preparation
verify that subfloor panels are properly
fastened to framing members.
any leveling of the subfloor must be done
prior to installing DITRA-HEAT and DITRA-
HEAT-DUO.
Movement Joints
DITRA-HEAT and DITRA-HEAT-DUO 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 13 of this Handbook, TCNA
EJ171, and TTMAC 301 MJ.
Setting and Grouting Materials
modified thin-set mortar - ANSI A118.11
unmodified thin-set mortar – ANSI A118.1
grout – ANSI A118.3, A118.6, A118.7, A118.8
Setting and Grouting Specifications
tile – ANSI A108.5
grout – ANSI A108.6, A108.9, A108.10
Other Considerations
tightly butted and/or tented plywood or OSB
seams must be addressed prior to installing
DITRA-HEAT and DITRA-HEAT-DUO.
vapor barrier on crawl space floors according
to regional building codes.
where a waterproof floor is required, all
DITRA-HEAT and DITRA-HEAT-DUO seams
and floor/wall transitions must be sealed
with KERDI-BAND using Schluter SET™,
Schluter ALL-SET™, Schluter FAST-SET™, or
unmodified thin-set mortar; see page 12.
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.
DITRA-HEAT’s uncoupling function protects the ceramic or stone tile covering from the aforementioned deformations by
neutralizing the differential movement stresses between the wood structure and the tile, thus eliminating the major cause
of cracking and delaminating of the tiled surface. Therefore, DITRA-HEAT can replace a second layer of plywood in most
applications.
Since wood structures are sensitive to moisture, DITRA-HEAT’s waterproofing function adds an essential element to the
flooring assembly by providing simple, effective, and permanent moisture protection.
Wood continually absorbs and releases moisture. The free space beneath the DITRA-HEAT membrane allows the wood to
breathe and provides a route for any residual moisture in the wood substrate to escape.
Since DITRA-HEAT is virtually incompressible within the tile assembly, the advantages of uncoupling are achieved without
sacrificing point load distribution capabilities.
By addressing all of the challenges associated with today’s fast, lightweight construction methods, DITRA-HEAT provides a durable
installation system for ceramic and stone tile over wood substrates.
DITRA-HEAT combines the flexibility of loose heating cables with the ease of installation of mat systems. Cables can be placed wherever
heat is desired, without creating height differences in the floor. Self-leveling compounds are not required to encapsulate the cables,
significantly reducing installation time and effort compared to uncoupling membranes over other electric floor warming systems.
Ceramic or porcelain tile
Schluter SET™, Schluter ALL-SET™,
Schluter FAST-SET™, or unmodified
thin-set mortar
DITRA-HEAT
or DITRA-HEAT-DUO
uncoupling membrane
and heating cables
Schluter ALL-SET™,
Schluter FAST-SET™,
or modified thin-set mortar
Single layer of
plywood or OSB
Joists, I-joists, or
trusses