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Commercial Properties Atlanta Grout & Tile Care
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SETTING MATERIALS SELECTION GUIDE
Introduction The following are the most widely used materials for setting ceramic, glass, and natural stone tiles. Each possesses specific qualities that make it suitable for installing tile over certain backings or under a given set of conditions. The conventional portland cement mortar method, including the one-coat method, is the only recognized thick-bed method. All others are thin-bed methods and are covered by existing trade jurisdictional decisions of record. Dry-set mortars and latex-portland cement mortars can be used in lieu of neat cement as a 1/16”-thick bond coat to bond ceramic, glass, and natural stone tiles to a portland cement mortar bed that is still workable. They can also be used on a cured portland cement mortar bed (minimum 3/32” thickness after tile is embedded) according to ANSI A108.1B. A neat cement bond coat can be used only when the portland cement mortar is still workable (A108.1A). Absorptive ceramic and stone tiles must be soaked before setting on a mortar bed that is still workable when using a neat portland cement bond coat. Under normal job conditions, a minimum of 20 hours cure at 70°F is adequate, but longer mortar bed cures of up to 10 days are desirable. When epoxy mortars, epoxy adhesives, furan, or organic adhesives are used, the mortar bed must be dry. To ensure practical and satisfactory installations, the cement mortar bed to receive the tile, whether left workable or allowed to harden, is to be applied by the tile contractor who must establish all the finished dimensions at the time this bed is applied. Non-cement setting materials such as epoxies and furans offer properties not possible with cement-based mortar (e.g., chemical resistance, quick setting times). However, special skills on the part of the tile setter may be required. Neat Cement and Portland Cement Mortar Portland cement mortar is a mixture of portland cement and sand, roughly in proportions of 1:5 for floors, and of portland cement, sand, and lime, in proportions of 1:5:1/2 to 1:7:1 for walls. Portland cement mortar is suitable for most surfaces and ordinary types of installation. A mortar bed, up to 2” in thickness, facilitates accurate slopes or planes in the finished tilework on floors and walls. The mortar bed can be modified with the inclusion of a latex/redispersible polymer per the manufacturer’s directions as part or all of the liquid portion of the mixture to enhance certain performance properties. There are two equivalent methods recognized for installing ceramic, glass, and natural stone tiles with a portland cement mortar bed on walls, ceilings, and floors. They are: the method covered by ANSI A108.1A, which requires that the tile be set on a mortar bed that is still workable; and the method covered by ANSI A108.1B, which requires that the tile be set on a cured mortar bed with dry-set or latex/polymer modified portland cement mortar. Absorptive ceramic and stone tiles must be soaked before setting on a mortar bed that is still workable when using a neat portland cement bond coat. Portland cement mortars can be bonded to concrete floors, backed with membranes and reinforced with wire mesh or metal lath, or applied on metal lath over open studding on walls. They are structurally strong, are not affected by prolonged contact with water, and can be used to plumb and square surfaces installed by others. Suitable backings when properly prepared are: brick or cement masonry, concrete, wood or steel stud frame, rough wood floors, plywood floors, foam insulation board, gypsum board, and gypsum plaster. The one-coat method may be used over masonry, plaster, or other solid backing that provides firm anchorage for metal lath. Dry-Set Mortar Dry-set mortar is a mixture of portland cement with sand and additives imparting water retentivity that is used as a bond coat for setting tile. Dry-set mortar is suitable for thin-bed installations of ceramic and natural stone tiles over a variety of surfaces. It is used in one layer nominally between 3/32” and 1/4” after tiles are embedded, has excellent water and impact resistance, is water cleanable, nonflammable, good for exterior work, and does not require soaking of tile. Dry-set mortar is available as a factory-sanded mortar to which only water need be added. Cured dry-set mortar is not affected by prolonged contact with water, but does not form a water barrier. It is not intended to be used in truing or leveling the work of others. Suitable backings, when properly prepared, include plumb and true masonry, concrete, gypsum board, cement backer board, fiber-cement backer board, cementitious coated foam backer board, cured portland cement mortar beds, brick, ceramic tile, and dimension stone. Consult membrane and setting material manufacturer for use over uncoupling membranes, waterproof membranes, and crack isolation membranes. Latex/Polymer Modified Portland Cement Mortar Latex/Polymer modified portland cement mortar is a mixture of portland cement, sand, and special latex/polymer additive that is used as a bond coat for setting tile. The uses of latex/polymer modified portland cement mortar are similar to those of dry-set mortar. Latex/polymer additives for use in thin-bed portland cement mortars are designed to improve adhesion, reduce water absorption, and provide greater bond strength and resistance to shock and impact. These additives allow some latitude in time, working conditions, and temperatures. Therefore, latex/polymer modified portland cement mortar is required for the installation of porcelain tile. When latex/polymer modified portland cement mortar is used to install ceramic, glass, and natural stone tiles in an area that may not thoroughly dry out in use (e.g., swimming pools and gang showers, etc.) or where initial drying is inhibited (between tile and impervious substrates), it is recommended that the completed installation be allowed to dry out thoroughly before exposure to water. This drying period can range from 14 to more than 60 days depending upon the temperature and humidity and other climatic conditions, and whether the installation is interior or exterior. Consult setting material manufacturer for minimum set times before grouting tile or allowing traffic, water exposure, or submersion. When installing 8” x 8” or larger impervious tile over a waterproof or crack isolation membrane, or other impervious substrate, longer curing times will be required. A rapid-setting latex/polymer modified cement mortar may need to be specified for faster curing. Because latices vary considerably, the directions of the latex/polymer mortar manufacturer must be followed explicitly. Not all latex/polymer modified portland cement mortars are suitable for wet areas. Consult manufacturer for suitability for intermittent and submerged applications. Exterior Glue Plywood (EGP) Latex Portland Cement Mortar EGP mortar is a latex/polymer modified portland cement mortar specifically for bonding ceramic, glass, and natural stone tiles to exterior glue plywood. When added in latex form, the polymer is added as a replacement for part or all of the gauging water in accordance with the manufacturer’s instructions. Complete installation and material specifications are contained in ANSI A108.12 and ANSI A118.11. For applicable ISO material specifications, see ISO C, P criteria.
Medium Bed Mortar Medium bed mortars are designed to minimize slump and facilitate thicker bond coats, as compared with non-medium-bed mortars. These characteristics make them useful for setting heavy tiles and/or tiles with ungauged thickness and for setting tiles with at least one side greater than 15” where the final embedded thickness of the mortar will exceed 3/16” under the tile. They are intended to be used as bond coats 3/16” to 3/4” thick after the tile is embedded; they are designed as direct bond adhesives and are not intended to be used in truing or leveling underlying substrates or the work of others. Medium-bed mortars are defined as such by their manufacturers. Epoxy Mortar Epoxy mortar is a mortar system designed for chemical resistance employing epoxy resin and epoxy hardener portions. Epoxy mortar is suitable for thin-bed installations of ceramic and natural stone tiles where chemical resistance of floors, high bond strength, and high impact resistance are important considerations. High-temperature-resistant formulas are also available. Acceptable substrates, when properly prepared, include concrete, wood and plywood, steel plate, ceramic tile, and stone tile. Application is made in one thin layer. Pot life, adhesion, water-cleanability before cure, and chemical resistance vary with manufacturer. Epoxy grout is also available. See Grout Selection Guide. Modified Epoxy Emulsion Mortar Modified epoxy emulsion mortar is a mortar system employing emulsified epoxy resin and hardener with portland cement and silica sand. Modified epoxy emulsion mortars are formulated for thin-bed installations of ceramic and natural stone tiles on floors and walls, interior and exterior. Their features include high bond strength, ease of application, little or no shrinkage, and economical epoxy application. They are not designed for chemical resistance. Recommended uses include residential floors over substrates such as cementitious backer units and concrete. Where complete and firm support under the tiles is mandatory, 95% coverage is required. This material is recommended by most manufacturers as a bond coat or setting material. Some also recommend it for grouting. Furan Resin Mortar Furan resin mortar is a mortar system designed for chemical resistance consisting of furan resin and furan hardener portions. Furan mortar is suitable for thin-bed installations of ceramic tile where chemical resistance of floors is an important consideration. Acceptable subfloors, when properly prepared, include concrete, wood and plywood, steel plate, and ceramic tile. They are typically not used in the installation of glass or stone tiles. Furan grout is also available. See Epoxy Adhesive Epoxy adhesive is an adhesive system employing epoxy resin and epoxy hardener portions. Epoxy adhesive is formulated for thin-bed installations of ceramic and stone tile on floors, walls, and counters. It is designed primarily for high bond strength and ease of application and not for optimum chemical resistance. However, its chemical and solvent resistance tends to be better than that of organic adhesives. Spot-Bonding Epoxy Spot-bonding epoxy is a multi-component high-strength epoxy adhesive designed for spot-bonding ceramic tile and stone. Organic Adhesive Organic adhesive is a prepared organic material for interior use only, ready to use with no further addition of liquid or powder, which cures or sets by evaporation. Organic adhesives are suitable for setting ceramic tile on floors, walls, and countertops, where surfaces are appropriate and properly prepared in accordance with adhesive manufacturer’s directions. Adhesives are applied in one thin layer with a trowel, first using the flat edge for continuous coverage and then the notched edge for uniform thickness. Where leveling or truing is required, an underlayment is used. Adhesives are not suitable for swimming pools, exteriors, or areas exposed to temperatures exceeding 140ºF. They supply some flexibility to the tile facing. Bond strength varies greatly among the numerous brands available. Solvents in some adhesives are irritating to some persons, and some adhesives are flammable.
All Information comes from Tile Council of North America Handbook
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