and material specifications are con- tained in ANSI A108.1 for installation when bed is still plastic, and for cured float bed and thin set applications. 3.1.2 Thin-Set Mortar [Thin Bed (ANSI A118.1)] 3.1.2.1 Thin-set mortar is a mixture of portland cement with sand and addi- tives providing water retention, and is used as a bond coat for setting stone. 3.1.2.2 Installation Methods. Thin- set mortar is suitable for use over a variety of surfaces. The stone should be properly tamped in place into the mortar, which will be one layer as thin as 3/32” after tamping. Thin set mortar has excellent water and impact resistance, can be cleaned with water, is nonflammable and good for exterior work. 3.1.2.3 Thin-set mortar is available as a factory-sanded mortar to which only water need be added. Cured thin 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 trueing or leveling the substrate surfaces as tile is being installed. 3.1.2.4 Suitable backings. When prop- erly prepared and in sound structural condition, suitable backings include plumb and true masonry, concrete, gypsum board, cementitious backer units, terrazzo, cured portland cement mortar beds, brick, ceramic tile, and dimension stone. Existing control joints including divider strips shall be main- tained. Polished, glossy, honed, or smooth backup surfaces shall be rough- ened by sanding or scarifying. See ANSI A108.01 General Requirements: Subsurfaces and Preparations by Other Trades. 3.1.2.5 Installation and Material Specifications. Complete installation Planitop® 330 Fast is a quick- setting, polymer-modified, fiber- reinforced cementitious render- ing, patching and leveling mortar. It can be applied from 1/8” to 1-1/4” (3 mm to 3,2 cm) thickness in a sin- gle coat. Planitop 330 Fast can be used for ramp- ing, smoothing and leveling clean, interior and exterior concrete and screed floor substrates to prepare them for installing ceramic, stone or waterproofing systems. Eliminating the need for a latex additive, Planitop 330 Fast requires only mixing with water to produce a non-sagging mortar that bonds directly to the substrate, readying it for tile installation in as little as 90 minutes. Because Planitop 330 Fast provides a superior flat finish, it produces an excellent substrate for the installation of thin tile and gauged porcelain tile panels. Planitop 330 Fast has the added environmental benefit of having been verified “Red List Free” per the most current Red List on the Living Building Challenge web- site. www.mapei.us. STONE –––––––––––––––––––––––––––––––––––––––––––––––––––––––––––– 78 TileLetter | May 2018