Figure 7-41.-Blocks laid in relief.
make a decorative wall called a PIERCED or
SCREEN wall. Other architectural effects can be
achieved by laying some block in relief (fig. 7-41)
or by varying the type of mortar joint.
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.
STRUCTURAL CLAY TILE MASONRY
Hollow masonry units made of burned clay
or shale are called, variously, structural tiles,
Figure 7-42.-Use of modular dimensions in concrete masonry wall openings.