Section 2121 High-Velocity Hurricane Zones— Construction Details
Unless otherwise required by design, all tie beams shall have four #3 ties at 12 inches (305 mm) on center. at corners and at each bend and at 48 inches (1219 mm) on center elsewhere. A tie beam shall be not less in dimension or reinforcing than required for the conditions of loading nor less than the following minimums: a tie beam shall have a width of not less than a nominal 8 inches (203 mm), shall have a height of not less than 12 inches (305 mm) and shall be reinforced with not less than four #5 reinforcing bars placed two at the top and two at the bottom of the beam except that a tie beam using "U" type beam block may be used with the following limitations:
- Limited to one-story Group R-3 occupancy.
- Limited to unsupported spans of 7 feet (2.1 m).
- Beam block shall be reinforced with one #7 bar in the top and one #7 bar in the bottom of the pour.
- Beam block shall provide not less than 14 inches (356 mm) vertical dimension or less than 41/2 inches (114 mm) horizontal dimension of poured-in-place beam cross-section.
- Where beam blocks are used, consideration of resistance to uplift caused by wind forces shall be based on only that portion of the dead load above the topmost mortar joint in the wall.
- In all brick walls at least every sixth course on both sides of the wall shall be a header course or there shall be at least one full header in every 72 square inches (0.05 m2) of each wall surface.
- In walls more than 12 inches (305 mm) thick, the inner joints of header courses shall be covered with another header course that shall break joints with the course below.
- Solid-unit masonry shall comply with the standard Building Code Requirements for Masonry, ANSI A41.1.
- Rubble stone walls shall be 4 inches (102 mm) thicker than is required for solid brick or concrete walls of the same respective heights, but in no part less than 16 inches (406 mm).