Where existing conditions prevent installation of lateral braces in accordance with Section 1707.2, lateral braces shall be permitted to be omitted for Retrofit Configurations A and B, as defined in Table 1704.1, provided all of the following conditions are met. This method is not allowed for Retrofit Configurations C or D.
The lateral brace on each side of an omitted lateral brace shall be fastened to each attic-framing member that they cross using three (3) 3-inch long fasteners. Fasteners shall be spaced a minimum of 1/2 inch (13 mm) from the edges of the lateral braces, a minimum of 23/4 inches (70 mm) from ends of lateral braces, and a minimum of 1 inch (25.4 mm) from adjacent fasteners.
All three retrofit studs shall have their attic interior edges aligned such that they snuggly butt the strong back to be installed between the two lateral braces on either side of the omitted lateral brace.
A strong back of minimum 2 × 6 lumber shall be installed parallel to the gable end and shall be located on and span between the lateral braces on the two sides of the omitted lateral brace. The strong back shall extend a minimum of 23/4 inches (70 mm) beyond the outer edges of the lateral braces and be snuggly butted against each of the three retrofit studs. The strong back shall be attached to each of the lateral braces on which it rests with four (4) 3-inch fasteners. The fasteners shall be placed a minimum 1/2 inch (13 mm) from all edges, a minimum of 2-inch (51 mm) spacing between fasteners, and a minimum of 23/4 inches (70 mm) from ends of the lumber members.
The retrofit stud at the location of the omitted lateral braces shall be fastened to the strong back using a connector with minimum uplift capacity of 800 pounds (363 kg) as specified by the manufacturer for use with spruce-pine-fir or hem-fir lumber and installed such that this capacity is oriented in the direction perpendicular to the gable end wall.
Lateral braces at ends of strong backs shall be permitted to be interrupted in accordance with Section 1707.4.2; but shall not be permitted to be shortened using the alternative method of Section 1707.4.3.
Branch lines permitted to omitlateral sway bracing by 9.3.5.5.10 shall not be omitted from load calculations for the mains serving them in 9.3.5.9.6 ...
