1707.5 Lateral Brace Connections to Webs of Trusses

Where existing conditions prevent installation of lateral braces on top or bottom chords of trusses, they shall be permitted to be installed on diagonal webs or vertical members of trusses provided all of the following conditions are met.

1. Lateral braces shall be positioned as close to the ceiling or roof diaphragms as existing conditions permit without altering trusses or any of their components.
2. Anchor blocks shall be installed between each pair of attic-framing members along the length of the lateral brace except for the framing member space next to the gable end wall. Anchor blocks can be installed on the narrow or wide face of lateral braces.
3. Anchor blocks shall be minimum ¹⁵/₃₂-inch plywood, ⁷/₁₆-inch OSB, or nominal 2-inch thick #2 spruce-pine-fir lumber or better.
4. Anchor blocks shall be sized to extend toward the nearby ceiling or roof diaphragm to within 3¹/₂ inches (89 mm) of the diaphragm. Anchor blocks shall butt against chords or diagonals or vertical webs of trusses or truss plates with a maximum gap of ¹/₈ inch (3 mm).
5. Anchor blocks shall be fastened to lateral braces with 8d common or 10d common nails or #9 screws with minimum penetration into lateral braces equal to the thickness of the anchor blocks or 1 inch (25.4 mm), whichever is greater. The minimum number of fasteners shall be the maximum that can be placed in a row with a minimum 2³/₄ inches (70 mm) distance between fasteners and 2³/₄ inches (70 mm) distance to ends of anchor blocks except that the number need not exceed three fasteners for nominal 2-inch thick lumber anchor blocks.