Masonry Magazine September 1976 Page. 16
The resulting thickness of mortar in back of the units shall be not less than 1/2 inch not more than 1-1/4 inches.
Units of tile, masonry, stone or terra cotta, not over 1 inch in thickness shall be restricted to 81 square inches in area unless the back side of each unit is ground or box screeded to true up any deviations from plane. These units and glass mosaic units of tile not over 2 inches by 2 inches by 3/8 inch in size may be adhered by means of portland cement. Backing may be of masonry, concrete or portland cement plaster on metal lath. Metal lath shall be fastened to the supports in accordance with the requirements of Chapter 47 of the Uniform Building Code. Type S mortar shall be applied to the backing as a setting bed. The setting bed shall be a minimum of 3/8 inch thick and a maximum of 3/4 inch thick. A paste of neat portland cement or half portland cement and half graded sand shall be applied to the back of the exterior veneer units and to the setting bed and the veneer pressed and tapped into place to provide complete coverage between the mortar bed and veneer unit. A portland cement grout shall be used to point the veneer.
NATIONAL CONCRETE MASONRY ASSOCIATION
P.O. Box 135, McLean, Virginia 22101