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A guide to ceramic & stone floor tile setting compounds: this article discusses setting compounds used to install ceramic, stone, and similar floor tiles. We discuss organic mastics, dry-set mortar, polymer modified mortar, and modified expoxy or expoxy adhesives and mortars. We address the installation details for each tile types. Also see flooring basics at Floor Designs: Kitchen & Bathroom and see Floor Tile, Ceramic for K & B. This article series discusses current best design practices for kitchens and bathrooms, including layout, clearances, work space, and accessible kitchen and bathroom layout, clearances, turning space, grab bars, controls, etc. Green links show where you are. © Copyright 2013 InspectAPedia.com, All Rights Reserved. Author Daniel Friedman. Ceramic & Stone Floor Tile Setting Compounds Selection Guide
Our photo (left) illustrates a bath restoration in an 1860's home, performed by the editor in the 1980s. Because the original wood flooring was badly deteriorated we installed 3/4-inch solid core plywood and then set these tiles in thin-set tile bedding compound. Manufacturers offer a wide range of setting compounds formulated for different setting beds and conditions. Choosing the wrong one can result in a failed tile job. For example, applications subject to moisture, temperature extremes, and heavy loading will need a higher quality setting compound than a kitchen backsplash, where organic mastic may serve perfectly well. If applying mortar to a thickness of over 1/4 inch to even out low spots in the floor or irregularities in the tile, use a medium-set mortar or multipurpose thinset suited to the task. With any product, it is important to follow the manufacturer’s instructions regarding application and compatibility with the particular substrate (see Table 6-7). [Click any image or table to see an enlarged version with additional detail, commentary & source citation.]
Organic Mastics Used for Floor TilesThese are ready-to-use adhesives primarily used with drywall and plywood substrates, although some are also approved for concrete and cement backerboards. Most now use a water-soluble formula, although some still use petroleum-based solvents. In general, mastics are the least expensive setting material and provide the least strength and flexibility. The substrate must be very flat, since mastic is troweled on thin and cannot bridge low spots or uneven joints. Mastic should be avoided in applications subject to high temperatures. Type II mastic is rated for use on walls not subject to wetting. Type I is approved for use on floors and wet areas. However, thinset mortars are better suited for floors and wet applications, for a modest increase in cost. Dry-Set Mortar Use for Floor TilesDry set mortar for floor tile installation is a factory blend of sand, cement, retarders, and other additives that is mixed with water on the job site. It provides a strong bond and high compressive strength, making it more suitable on floors than organic mastic. It is commonly used over concrete slabs, mortar beds, or cement backerboards. It cleans easily with water; but once dried, it is unaffected by water. Polymer-Modified Mortar Uses for Floor Tile InstallationPolymer modified mortar for floor tiles is essentially dry-set mortar with latex or acrylic polymers added to increase the bond strength, compressive strength, and flexibility of the compound. One formulation uses a latex or acrylic liquid added to the dry mix at the job site. The other has dry polymers blended into the dry mix at the factory so only water is added on site. Polymer-modified mortar bonds well to most substrates, including waterproofing membranes, to provide a premium waterproof system. Some kinds are not recommended for use with plywood, however (always check the label for compatibility with a substrate). Cleanup should be done quickly with a damp sponge while the material is wet, or it is difficult to remove from skin and materials. Modified-Epoxy Mortar and Grout System for Floor Tile InstallationEpoxy mortar for flooring is generally used for floors and countertops that require moderate chemical resistance, or where higher bond strength is needed to withstand greater loading, impacts, and flexing. It is also useful with questionable substrates such as existing tile, sheet vinyl, or plastic laminate, all of which are suitable for epoxy as long as they are sound and the surfaces are roughed up. In addition to their higher cost, these products have precise mixing requirements, a short pot life, and more difficult cleanup than standard thinsets. High-chemical-resistance formulations are also available. Cleanup of dried material requires special solvents, and the silica sand presents a respiratory hazard. Because of the mixing requirements and faster setup, skilled applicators are required. Epoxy Adhesive & Grout Floor Tile DetailsEpoxy adhesive is often used to install green (serpentine), white, and other moisture sensitive marbles and marble agglomerates that may stain or warp with water-based products. It provides high-bond strength and impact-resistance over most sound substrates, including plywood. It also provides water-resistance and moderate chemical-resistance. It requires precise mixing and skilled application, and special solvents are required to remove any material that dries on the surface of the tile (or the installer’s hands). Also, the silica sand presents a respiratory hazard. Guide to Tile Installation with Thinset MortarsThinset ApplicationAll mastics and thinset mortars
are applied in the same way. First apply a thin layer of the
adhesive using the flat edge of the trowel for continuous
coverage, then comb with the notched edge of the trowel
to create a uniform, flat setting bed. Hold the trowel at
about 30 degrees from the surface for the continuous layer
and at about 45 degrees when combing with the notched
edge (Figure 6-39 shown below).
Notches range from about 3/16 inch for thin tile to 3/8 inch for tiles 12x12 inches and larger or irregular tiles such as handmade pavers. A 1/4 -inch notch works for most other tiles. Always follow the directions on the can. Coverage varies depending on the type of substrate and tile, as well as the heat and humidity in the environment. this is particularly important with tile 12x12 inches or larger. Also apply thinset mortar to only one small section at a time—no larger than the area that can be tiled before the thinset skins over. Any thinset that skins over will have to be discarded. Medium-Set Application for TilesWhere irregularities in the substrate or tile shape, such as handmade pavers, require a setting bead thicker than 1/4 inch, choose a medium-set mortar or an all-purpose thinset approved for medium-set usage. Other thinset mortars are not strong enough when built up to that depth. Irregular-shaped tiles will need some adhesive “back buttered” directly to the tile to obtain proper coverage. Tile Installation Using Thinset and Medium Set MortarsNext press and twist in a sample tile to
check the adhesive coverage. ANSI standards require that
dry interior tiles be evenly covered over at least 80% of their
surface area (Figure 6-39b).
Wet or exterior applications require
95% coverage. When set back in place and beat in with
a rubber mallet (larger tiles) or beating block (smaller tiles
such as mosaics), the setting bed should be about 3/32
inch but
not larger than 1/4 inch, unless medium-set mortar is used.
Irregular-shaped handmade tiles need some adhesive “back
buttered” directly to the tile to obtain proper coverage. Kitchen and Bath Product Manufacturers, Sources, AssociationsCeramic Tile-Setting Material Manufacturer ListBonsal American www.bonsal.com Setting compounds, grouts, preformed shower pans, curbs, and niches. Also, distributor of backerboards, isolation membranes, and other tile-setting products Color Caulk, div. of Roanoke Companies Group www.colorcaulk.com Color-matched caulking Custom Building Products www.custombuildingproducts.com Elastomeric and liquid-applied membranes, self-leveling underlayments, setting compounds, and grouts Laticrete International www.laticrete.com Trowel-on membranes, self-leveling underlayments, setting compounds, grouts, and sealants Noble Company www.noblecompany.com CPE sheet membranes, trowel-on membranes, clamping ring drains, and preformed slopes, niches, and curbs Mapei www.mapei.com Trowel-on and sheet membranes, self-leveling underlayments, setting compounds, grouts, and color-matched sanded caulks Ceramic Tile Backerboard ProducersCustom Building Products www.custombuildingproducts.com Wonderboard cement backerboard, Easyboard cement and polystyrene lightweight backerboard, and Rhinoboard fiber-cement backerboard Georgia-Pacific Gypsum www.gp.com/build Denshield gypboard backer with glass-matt facing James Hardie Building Products www.jameshardie.com Fiber-cement backerboard National Gypsum www.nationalgypsum.com Permabase lightweight cement and polystyrene backerboard Schluter Systems www.schluter.com Kerdi tile membrane goes directly over drywall or other substrates T. Clear Corp./Fin Pan Inc. www.finpan.com Util-A-Crete lightweight concrete backerboard U.S. Gypsum www.usg.com Durock cement backerboard W. R. Bonsal www.bonsal.com Extruded polystyrene backerboard with fiberglassreinforced cement facing Kitchen & Bath Industry AssociationsAssociation of Home Appliance Manufacturers(AHAM) www.aham.org National Kitchen and Bath Association (NKBA) www.nkba.org Ceramic Tile Institute of America www.ctioa.org Home Ventilation Institute (HVI) www.hvi.org Marble Institute of America www.marble-institute.com Porcelain Enamel Institute (PEI) www.porcelainenamel.com Tile Council of America (TCA) www.tileusa.com -- Adapted with permission from Best Practices Guide to Residential Construction. Frequently Asked Questions (FAQs)... Ask a Question or Search InspectApedia
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