R603.9.2 Determination of Minimum Length of Fullheight Sheathing
The minimum length of full-height sheathing on each braced wall line shall be determined by multiplying the length of the braced wall line by the percentage obtained from Table R603.9.2(1) and by the plan aspect-ratio adjustment factors obtained from Table R603.9.2(2). The minimum length of full-height sheathing shall be not less than 20 percent of the braced wall line length.
To be considered full-height sheathing, structural sheathing shall extend from the bottom to the top of the wall without interruption by openings. Only sheathed, fullheight wall sections, uninterrupted by openings, which are not less than 48 inches (1219 mm) wide, shall be counted toward meeting the minimum percentages in Table R603.9.2(1). In addition, structural sheathing shall comply with all of the following requirements:
- Be installed with the long dimension parallel to the stud framing and shall cover the full vertical height of wall from the bottom of the bottom track to the top of the top track of each story. Installing the long dimension perpendicular to the stud framing or using shorter segments shall be permitted provided that the horizontal joint is blocked as described in Item 2.
- Be blocked where the long dimension is installed perpendicular to the stud framing. Blocking shall be not less than 33 mil (0.84 mm) thickness. Each horizontal structural sheathing panel shall be fastened with No. 8 screws spaced at 6 inches (152 mm) on center to the blocking at the joint.
- Be applied to each end (corners) of each of the exterior walls with a minimum 48-inch-wide (1219 mm) panel.
Exception: Where stone or masonry veneer is installed, the required length of full-height sheathing and overturning anchorage required shall be determined in accordance with Section R603.9.5.
MINIMUM PERCENTAGE OF FULL-HEIGHT STRUCTURAL SHEATHING ON EXTERIOR WALLSa, b
| WALL SUPPORTING | ROOF SLOPE | ULTIMATE WIND SPEED AND EXPOSURE (mph) | ||||
| 115 B | 126 B | < 139 B | 126 C | < 139 C | ||
| 110 C | 115 C | |||||
| Roof and ceiling only (one story or top floor of two- or three-story building). | 3:12 | 9 | 9 | 12 | 16 | 20 |
| 6:12 | 13 | 15 | 20 | 26 | 35 | |
| 9:12 | 23 | 25 | 30 | 50 | 58 | |
| 12:12 | 33 | 35 | 40 | 66 | 75 | |
| One story, roof and ceiling (first floor of a two-story building or second floor of a three-story building). | 3:12 | 27 | 30 | 35 | 50 | 66 |
| 6:12 | 28 | 30 | 40 | 58 | 74 | |
| 9:12 | 38 | 40 | 55 | 74 | 91 | |
| 12:12 | 45 | 50 | 65 | 100 | 115 | |
| Two stories, roof and ceiling (first floor of a three-story building). | 3:12 | 45 | 51 | 58 | 84 | 112 |
| 6:12 | 43 | 45 | 60 | 90 | 113 | |
| 9:12 | 53 | 55 | 80 | 98 | 124 | |
| 12:12 | 57 | 65 | 90 | 134 | 155 | |
FULL-HEIGHT SHEATHING LENGTH ADJUSTMENT FACTORS
| PLAN ASPECT RATIO | LENGTH ADJUSTMENT FACTORS | |
| Short wall | Long wall | |
| 1:1 | 1.0 | 1.0 |
| 1.5:1 | 1.5 | 0.67 |
| 2:1 | 2.0 | 0.50 |
| 3:1 | 3.0 | 0.33 |
| 4:1 | 4.0 | 0.25 |