Copyright Goodheart-Willcox Co., Inc. 248 Section 4 Techniques weight of building materials and occupants. Lateral loads include wind, soil, and seismic events. In most regions of the United States, only vertical loads and wind loads are a major concern, but in some areas, seis- mic loads may control the structural design. Addition- ally, severe wind loads, as in hurricane prone areas, may dictate the structural design. The size of a building’s structural member is determined by model building codes and the structural loads. Masons are required to familiarize themselves with the International Building Code (IBC) and the Inter- national Residential Code (IRC), but other codes may also be used in the design and construction process of a facility. When questions arise related to one of the codes, a local building official can be contacted to clar- ify construction process rules and regulations. Location of Interior Work Because there is no cavity within the exterior wall to place plumbing, heating/air-conditioning, and elec- trical systems, the systems must be located between the furring strips, in the floor or ceiling, or in interior frame walls. The type of foundation and floor system used influences the location of interior systems. In structures with basements or crawl spaces, mechanical systems can be located between the floor joists. In slab type structures, it is easier to route mechanical systems through the ceiling or attic space. Structural Materials According to BIA Technical Note 26—Single Wythe Brick Bearing Walls, selection of masonry materials for single wythe brick bearing wall systems should consider the structural, energy, and reinforcement performance requirements. The following are some considerations: ■ ■ Brick. The brick masonry units used in a single wythe bearing wall are solid (ASTM C216) or hollow (ASTM C652). Solid bricks are commonly manufactured in nominal widths of 3″, 4″, and 6″. Code Note Minimal Nominal Wall Thickness The International Residential Code (IRC) specifies an 8″ minimum nominal wall thickness for loadbearing masonry structures over one story in height. A nominal 6″ wall is permitted for a single-story home or garage if the wall height does not exceed 9′ and the gable height does not exceed 15′. Minimum wall thickness requirements influence the type and size of brick and block selections. Other model building codes have similar restrictions, so it is important to research the local codes. Hollow bricks are available in nominal widths of 4″, 5″, 6″, and 8″. Nominal 5″ and 6″ wide hollow bricks are most commonly used to build this type of wall for residential purposes. The cells in most hollow bricks are made to accommodate vertical reinforcement and grout. ■ ■ Mortar. Portland cement-lime mortars with an air content of less than 12% are recommended for their superior bond strength and resistance to water penetration. Masonry cements are prohibited by some codes and all type N mortars are prohibited in seismic performance categories D and E (formerly zones 3 and 4). Type S, M, or N mortar may be generally used in loadbearing brick masonry. Type S is recommended for use in reinforced brick bearing walls. ■ ■ Grout. Steel reinforcement is bonded to the surrounding brick masonry using grout. Grout may be made using fine or coarse aggregate, but fine aggregate is generally used because it is easier to fill smaller cells. Grout should meet ASTM C476. The water/cement ratio of grout should have a slump of 8″ to 11″. It must be fluid enough to fill voids, but not separate into its constituent parts. ■ ■ Reinforcement. Lateral loads must be resisted through the use of vertical steel reinforcement or other means. See Figure 12-62. The Masonry Standards Joint Committee (MSJC) Code limits the maximum size of reinforcement used in masonry to a No. 11 reinforcing bar. As a rule-of- thumb, the maximum bar size should not exceed the nominal thickness of the wall in inches to ensure proper development of the reinforcement. For example, a maximum reinforcing bar size No. 6 is recommended for nominal 6″ walls. Vertical reinforcement in grouted cell Brick Industry Association Figure 12-62. Vertical reinforcing used to resist lateral loads in a single wythe wall.