Concrete masonry walls should be laid out to make maximum use of full- and half-length units, thus minimizing cutting and fitting of units on the job. Length and height of walls, width and height of openings, and wall areas between doors, windows, and corners should be planned to use full-size and half-size units, which are usually available (fig. 7-42). This procedure assumes that window frames and doorframes are of modular dimensions that fit modular full- and half-size units. Then, all horizontal dimensions should be in multiples of nominal full-length masonry units, and both horizontal and vertical dimensions should be designed to be in multiples of 8 in. Table 7-2 lists nominal lengths of concrete masonry walls by stretchers, and table 7-3 lists nominal heights of concrete masonry walls by courses. When units 8 by 4 by 16 are used, the horizontal dimension should be planned in multiples of 8 in. (half-length units), and the vertical dimensions, in multiples of 4 in. If the thickness of the wall is greater or less than the length of a half unit, a special length unit is required at each corner in each course.

Hollow masonry units made of burned clay or shale are called, variously, structural tiles,

Table 7-2.-Nominal Length of Concrete Masonry Walls by Stretchers

Table 7-3.-Nominal Height of Concrete Masonry Walls by Courses

hollow tiles, structural clay tiles, structural clay hollow tiles, and structural clay hollow building tiles, but most commonly called building tile. In building tile manufacture, plastic clay is pugged through a die, and the shape that emerges is cut off into units. The units are then burned much as bricks are burned.