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.
- Lateral braces on each side of omitted lateral braces shall be 2 × 4 lumber placed approximately perpendicular to the attic-framing members and installed with their wide faces across attic-framing members. They shall be attached to a minimum of four (4) attic-framing members with attachment to the attic-framing member farthest from the gable end wall a minimum of 8 feet (2438 mm) from the exterior sheathing or siding on the gable end wall.
- 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.
- A retrofit stud shall be installed in accordance with Section 1706.4 at the location of the omitted lateral brace. This retrofit stud and both of the retrofit studs on either side of the omitted lateral brace shall be sized in accordance with Table 1704.1 for the largest of the retrofit studs required at any of the three locations.
- 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.
- Retrofit studs adjacent to the omitted lateral brace shall be fastened to their corresponding lateral brace using straps in accordance with the L-bent strap method of Section 1708.1.1 except that a compression block is not required. The U-bent strap method of Section 1708.1.2 is not allowed unless U-bent straps are routed around the exterior face of primary studs.
- 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.
For SI: 1 inch = 25.4 mm.
FIGURE 1707.4.1
OMITTED LATERAL BRACE