Bulletin #8

Revised April 19, 2006

Installation of Fixtures Soap Dishes, Seats, Towel Bars, Paper Holders, Etc.

The intent of this bulletin is to present the consensus of the MMSA members regarding the best known means to install fixtures currently used by the ceramic tile and stone industry. “SOAP AND GRAB” fixture is an obsolete name for a soap dish with a wash cloth holder. Any fixtures that include “GRAB BARS” ARE NOT RECOMMENDED. SOAP DISHES ONLY ARE PREFERRED. Safety bars, when required, should be non-ceramic and anchored mechanically to the structural wall.

*Regardless of the type of fixture used it is important that the fixture is properly attached, waterproofed, sloped, and transition joints and penetrations filled with an appropriate sealant.

1. Traditional Ceramic Fixtures

Recessed Type Fixtures

Cut a hole in the backup surface (Green Board, Plaster, Metal Lath, Backer Board) to permit the use of a wire basket or mechanical support for the setting mix. Provide blocking to properly waterproof and flash to prevent moisture migration into wall cavity. Make sure that when pressure is applied to the fixture during installation, that it is dispersed evenly to the surrounding wall surface. In wet areas, portland cement mortar, dry-set mortar, latex-portland cement mortar, or portland cement grouts should always be used in place of gypsum products such as patching plaster or plaster-of-paris. The reason is portland cement does not deteriorate from contact with moisture and normally develops greater bond strength through continued exposure. Use a proper ASTM C920 sealant per TCA EJ171 to seal transition joints of fixture to wall.

Surface Type Fixtures

Back-butter and adhere fixture directly to tile substrate with the appropriate thin-set dry set mortar, or preferably with a latex-portland cement mortar or grout setting mix that is compatible with the tile substrate . Support with masking tape or other mechanical means until it cures. Use a proper ASTM C920 sealant per TCA EJ171 to seal transition joints of fixture to wall.

Fixture installation on Gypsum Board requires special organic adhesives specifically recommended by the manufacturer. The area involved must be clean and dry, and should be masked when the job is laid out – do not trowel regular mastic there. Remember that the ultimate bond strength depends on the contact between the fixture and the adhesive, and adhesive and the back-up surface, as well as the strength of the back-up surface and the adhesive itself. Do not use portland cement mortar, dry-set mortars, latex-portland cement mortars, or portland cement-based grouts over gypsum board because they will absorb moisture. Only special moisture-proof materials such as the Neoprene and Silicone rubber based materials should be used. A recommend procedure is as follows:
a. Drill holes into the drywall.
b. Apply a sufficient amount of fixture adhesive to the back of fixture to make 100% contact with wall surface and back of fixture. Fill holes so that the adhesive protrudes completely through holes.
c. Insert the fixture in the desired location and press firmly for approximately ten seconds. Clean excess material from edges to permit proper application of sealant.
d. Support with masking tape or other mechanical means until adhesive sets and holds fixture in place.
e. Use a proper sealant per TCA EJ171 to seal transition joints of fixture to wall.

2. Preformed Niches

One Substrate Layer

Place preformed niche on wall centered and level to trace cut-out area. Cut along line and remove backing. Caulk to cross bracing studs with appropriate sealant. Tape and caulk joints to seal transition joints from niche to wall. Install tile using a latex-portland cement mortar.

Two Substrate Layers

Place preformed niche on wall centered and level to trace cut-out area of the back niche box. Cut along line and remove both layers of backing. Place preformed niche into opening and trace exterior flange cut-out. Cut outside layer only. Insert and caulk niche flush with top layer with appropriate sealant. Tape and caulk joints to seal transition joints from niche to wall. Install tile using a latex-portland cement mortar.

3. Custom Made Niches

Mortar Bed Application

Frame niche opening and provide continuous blocking. Provide a slope to drain of 1/16” per inch for horizontal shelf surface. Waterproof and flash with a vapor barrier material such as a Bituthene window flashing material. Weather-lap the membrane working up from bottom. Apply moisture barrier membrane over wall area weather-lapping working up from bottom. Fabricate a metal lath wire basket to fit into opening with at least 2” lap over wall transition and staple into place. Apply scratch and mortar bed maintaining shelf slope to drain. Install tile using a thin-set mortar. Caulk all lower niche transition joints with a proper ASTM C920 sealant per TCA EJ171.

Backer Board Application

Frame niche opening and provide continuous blocking. Provide a slope to drain of 1/16” per inch for horizontal shelf surface. Waterproof and flash with a vapor barrier material such as a Bituthene window flashing material. Weather-lap the membrane working up from bottom. Apply moisture barrier membrane over wall area weather-lapping working up from bottom. Attach backer board and tape joints maintaining shelf slope to drain. Install tile using a thin-set mortar. Caulk all lower niche transition joints with a proper ASTM C920 sealant per TCA EJ171.

4. Metal and other Surface Fixtures (including Safety Bars and seats)

Mechanical Attachment (for Safety Bars)

Drill holes through tile into structural wall studs or blocking with appropriate drill type and size. Use appropriate screws or lag bolts for the application. Fill hole with silicone or urethane sealant before inserting screw or bolt making sure head of screw or bolt is embedded in the sealant when complete.

Surface Attachment (not for Safety Bars)

Use an appropriate high strength silicone sealant for adhering metal frame or bracket to a clean ceramic tile or stone surface without contaminates. Support with masking tape or other mechanical means until adhesive sets and holds fixture or bracket in place.

Stone Corner Triangular Seat Surface Attachment

Use an appropriate 2 cm minimum thickness high strength stone suitable for wet areas. Notch field tile in an inside 90 degree corner to allow triangle shaped stone to sit on field tile edge and fit tightly within notched area. Use a high strength modified thin-set to butter stone edge and substrate, and then place in notched area. Support with masking tape or other mechanical means until thin-set sets seat in place. Use an ASTM C920 sealant for caulking around seat after thin-set has cured and before use.