Installation Guide

6 WOOD — Floors, Interior
Floors, Interior - Natural Stone Tile
DH-W-S-17
Double layer of OSB or Plywood subfloor
Areas of Application
over any even and structurally sound double
layer OSB or plywood floor
interior dry or wet areas
Limitations
requires double layer wood floor regardless
of joist spacing
minimum 2" x 2" (50 mm x 50 mm) tile
Requirements
maximum spacing of joists, I-joists, or floor
trusses is 24" (610 mm) o.c.
double layer wood floor consisting of:
• minimum subfloor thickness – 23/32",
3/4" nom. (19 mm) tongue-and-groove
• minimum underlayment thickness –
11/32", 3/8" nom. (10 mm)
Substrate Preparation
verify that subfloor panels are properly
fastened to framing members.
underlayment – minimum 11/32", 3/8" nom.
(10 mm)-thick Exposure 1, plugged-face
plywood or OSB with 1/8" (3 mm) gap
between sheets; see page 14 for
underlayment installation guidelines.
any leveling of the subfloor must be done
prior to installing DITRA-HEAT and DITRA-
HEAT-TB.
Movement Joints
DITRA-HEAT and DITRA-HEAT-TB 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 11 of this Handbook, TCNA
EJ171, and TTMAC 301 MJ.
Setting and Grouting Materials
latex portland cement (p.c.) 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
certain moisture-sensitive stones, e.g., green
marble, or resin-backed tiles may require
special setting materials. Consult stone
supplier and Schluter
®
-Systems for more
information.
tightly butted and/or tented plywood or OSB
seams must be addressed prior to installing
DITRA-HEAT and DITRA-HEAT-TB.
vapor barrier on crawl space floors according
to regional building codes.
where a waterproof floor is required, all
DITRA-HEAT and DITRA-HEAT-TB seams
and floor/wall transitions must be sealed with
KERDI-BAND using unmodified thin-set
mortar; see page 10.
Natural stone tile
Unmodified thin-set mortar
DITRA-HEAT
or DITRA-HEAT-TB
uncoupling membrane
and heating cables
Latex p.c. mortar
Double layer of plywood
or OSB
Joists, I-joists, or
trusses