Shower System Installation Handbook

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SHOWER ASSEMBLY — Curbless 13

Areas of Application

Interior showers with curbless access.

Over wood or concrete subfloors. See the Base information under Requirements

(below) for details.

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 steam showers or may require special

setting materials. Consult stone supplier and Schluter

-Systems for more

information.

Requirements

Plywood, OSB, or concrete subfloor must be clean, even, and load bearing.

Ensure a suitable structure and substrate for the shower floor. This may require the

services of a qualified design professional (e.g., architect, engineer, etc.).

Recessing the floor of a bathroom must be done in a way that preserves the

structural integrity and safety of the construction. This may require the services of a

qualified design professional (e.g., architect, engineer, etc.).

Solid backing – gypsum wallboard, cementitious backer unit, fiber-cement

backerboard, fiber-reinforced water-resistant gypsum backerboard, coated glass

mat water-resistant gypsum backerboard, Portland cement mortar, concrete, or

masonry.

Base – KERDI-SHOWER-T/-TS/-TT/-LT/-LTS or Portland cement mortar bed.

Ramp – KERDI-SHOWER-R or Portland cement mortar bed.

Bench –KERDI-BOARD-SB, KERDI-BOARD, concrete, masonry block, or sawn

lumber sheathed with solid backing (see above).

KERDI-DRAIN/-LINE shall be properly supported.

KERDI-DRAIN/-LINE shall be connected to the waste line; use ABS cement for ABS

drains, PVC cement for PVC drains, a no-hub coupling for stainless steel drains with

no-hub outlets, and thread sealing compound or tape for stainless steel drains with

threaded outlets.

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 or KERDI-BOARD 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.

KERDI, DITRA or DITRA-HEAT shall be installed in all floor areas subject to water

exposure (i.e., wet area and drying area). Floor/wall connections shall be sealed with

KERDI-BAND.

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.

When using the stainless steel KERDI-DRAIN bonding flange, use

KERDI-FIX to bond KERDI to the drain.

All horizontal surfaces (e.g. benches, window sills, shelves, etc.) must be sloped

toward the shower drain.

Substrate Preparation

Verify that subfloor panels and solid backing are properly fastened to framing

members.

Any leveling of the subfloor must be done prior to installing KERDI-SHOWER-T/-

TS/-TT/-LT/-LTS/-R and KERDI-BOARD-SB prefabricated substrates.

Solid Backing Materials

Gypsum wallboard – ASTM C1396/C1396M

Cementitious backer unit – ANSI A118.9 or ASTM C1325

Fiber-cement backerboard – ASTM C1288

Fiber-reinforced water-resistant gypsum

backerboard – 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, A118.7

Installation Specifications

Solid backing panels – follow manufacturer’s directions

Portland cement mortar bed – ANSI A108.1B

Tile – ANSI A108.5

Grout – ANSI A108.6, A108.10

Other Considerations

If installing the KERDI-SHOWER-TT thin tray, the installation of a 5/8" or 3/4"

plywood/OSB on top of a wood subfloor and Schluter

-DITRA-HEAT or Schluter

DITRA-XL outside of the shower area is suggested to create a curbless shower

application. Due to the additional height, be sure to check the transition height at

the bathroom doorway.

Curbless tiled showers rely on the slope of the floor to effectively contain water in

the immediate shower area and direct water to the drain. Given the wide range of

potential configurations, it isn’t possible to address them all in this Handbook.

Waterproofing must be installed in all areas subject to water exposure. Install KERDI

over mortar beds. Use the DITRA or DITRA-HEAT uncoupling membrane over

plywood/OSB or concrete subfloors. All seams are sealed using KERDI-BAND.

Please refer to the Schluter

-DITRA or Schluter

-DITRA-HEAT Installation

Handbooks for complete details and warranty criteria.

If KERDI-LINE is placed at shower entrance, it is recommended that grate assembly

A, Pure, or the covering support (D) is chosen and that the drainage openings span

the maximum width of the entrance to limit potential overflow; secondary drainage

(e.g., KERDI-DRAIN) may be required in the drying area.

Schluter

-SHOWERPROFILE-WS/-WSK system profiles can be used to form a

splashguard at the entrance of curbless showers. See page 35.

Various building codes and other sources, such as the Americans with Disabilities

Act, include specific requirements for disabled access in public buildings and must

be consulted when applicable. Areas of interest may include degree of slope,

clearance, and supporting structures such as grab bars.

Shower grab bars must be anchored in the structure or solid blocking behind

KERDI-BOARD.

When KERDI-SHOWER-T/-TS/-TT/-LT/-LTS tray dimensions do not match the

dimensions of the shower compartment, the tray may be cut or extended with dry

pack mortar.

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.

A water test is strongly recommended before setting tile to verify a successful

installation. Wait 24 hours minimum after the membrane installation is complete to

allow for final set of thin-set mortar and ensure waterproof performance at seams

and connections. Refer to local plumbing codes for any specific requirements in

your area. For curbless showers a temporary dam must be provided at the

threshold to perform the water test.

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

-SHOWERPROFILE-S/-R profiles eliminate the need for cutting wedges of

tile by covering the exposed wall area where the floor slopes to KERDI-LINE.

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.

Curbless Showers – Ceramic or stone tile

K-SHBF-21

Schluter

-KERDI waterproofing membrane or

Schluter

-KERDI-BOARD waterproof building panel