Installation Guide

BATHTUB SURROUND 21
Areas of Application
Interior bathtub surrounds.
Limitations
Certain glass tiles may not be compatible with bonded waterproof
membranes and/or may require special setting materials. Consult glass
tile manufacturer and Schluter
®
-Systems for more information.
Certain moisture sensitive stones, e.g., green marble, or resin-backed
tiles may not be appropriate for use in wet areas such as bathtub
surrounds or may require special setting materials. Consult stone supplier
and Schluter
®
-Systems for more information.
Requirements
Solid backing – gypsum wallboard, cementitious backer unit, fiber-
cement underlayment, fiber-reinforced water-resistant gypsum
backerboard/underlayment, coated glass mat water-resistant gypsum
backerboard, Portland cement mortar bed, concrete, or masonry.
Solid backing panels or KERDI-BOARD shall either be installed flush with
the tub flange or over the tub flange leaving a minimum space of 1/4"
(6 mm) between the board and the tub deck.
Minimum KERDI-BOARD thickness – 1/2" (12.5 mm) for studs spaced at
16" (40.6 cm) o.c. and 3/4" (19 mm) for studs spaced at 24" (61 cm) o.c.
KERDI-BOARD shall be fastened to wood or metal framing with
appropriate screws (i.e., coarse thread wood screw for wood studs and
self-tapping for metal studs) and corresponding KERDI-BOARD-ZT
washers. Screws must reach a depth of at least 3/4" (20 mm) in wood
studs and 3/8" (10 mm) in metal studs. Maximum allowable on-center
fastener spacing is 12" (30 cm) for walls and 6" (15 cm) for ceilings.
KERDI waterproofing membrane or KERDI-BOARD waterproof building
panel shall be installed up to the height of the showerhead at minimum.
In enclosed shower areas, install KERDI or KERDI-BOARD on all
surfaces, including the ceiling, door jambs and the door header.
It is the specifier's responsibility to treat and address all penetrations
through the KERDI membrane or KERDI-BOARD (e.g., showerhead,
mixing valve, etc.) in the installation. All penetrations must be treated with
KERDI-SEAL-PS/-MV seals, KERDI-FIX or suitable sealant.
All horizontal surfaces (e.g., window sills, shelves, etc.) must be sloped
toward the bathtub drain. This can be done by sloping the substrate or
the tile.
Substrate Preparation
When using KERDI waterproofing membrane, verify that solid backing is
properly fastened to framing members.
Solid Backing Materials
Gypsum wallboard – ASTM C1396/C1396M
Cementitious backer unit – ANSI A118.9 or ASTM C1325
Fiber-cement underlayment – ASTM C1288
Fiber-reinforced water-resistant gypsum backerboard/underlayment –
ASTM C1278
Coated glass mat water-resistant gypsum backerboard – ASTM C1178
Portland cement mortar – ANSI A108.1B
Concrete
Masonry
Setting and Grouting Materials
Unmodified thin-set mortar – ANSI A118.1
Grout – ANSI A118.3, A118.6, or A118.7
Installation Specifications
Solid backing panels – follow manufacturer’s instructions
Portland cement mortar bed – ANSI A108.1B
Tile – ANSI A108.5
Grout – ANSI A108.6, A108.10
Other Considerations
When KERDI or KERDI-BOARD and tile are installed on the ceiling, the
solid backing and fasteners must be able to support the load of the tile
and setting and grouting materials.
Shower grab bars must be anchored in the structure or solid blocking
behind KERDI-BOARD.
Schluter
®
-Systems profiles may be used to finish and protect outside
corners and eliminate the use of sealant at inside corners; see page 40.
Schluter
®
-SHELF-E/-W/-N are alternatives to tiled shelves that can be
easily installed on walls and in corners and niches; see page 40.
Where a waterproof floor adjacent to the shower is desired, DITRA or
DITRA-HEAT uncoupling membranes shall be installed. Floor/wall
connections shall be sealed with KERDI-BAND.
Bathtub surround – Ceramic or stone tile
Schluter
®
-KERDI waterproofing membrane
or Schluter
®
-KERDI-BOARD waterproof building panel
K-TS-20