Copyright Goodheart-Willcox Co., Inc. Chapter 14 Wall Systems 287 Portland Cement Association Figure 14-17. The outer and inner wythes of masonry are bonded together by the mortar in the collar joint between them. Portland Cement Association Figure 14-18. Building a composite wall with six courses of brick between each header course. Goodheart-Willcox Publisher Figure 14-19. These well-placed facing units have extruded mortar on the backside in a composite wall. The mortar must be cut flush with a trowel. See Figure 14-19. Parging the backside of the facing is another method of bonding the wythes across the collar joint. See Figure 14-20. Facing headers are laid every seventh course in an 8″ composite wall. A 12″ composite wall is constructed in a manner similar to the 8″ composite wall. Figure 14-21 shows the facing header course being laid overlapping the header block. The header block can be laid with the recessed notch up or down, depending on construc- tion requirements. Figure 14-22 shows the seventh course backup wythe being constructed using stretcher block. Header blocks were used for the sixth course bonding. Portland Cement Association Figure 14-20. Bonding a wall across a collar joint by parging the backside of the facing. Goodheart-Willcox Publisher Figure 14-21. Header course being laid in composite wall.