Section 2322 High-Velocity Hurricane Zones— Sheathing
|PANEL SPAN RATING2||MAXIMUM PLYWOOD SPAN (IN.)3|
For SI: 1 inch = 25.4 mm.
- These values apply for sheathing C-D and C-C grades only. Spans shall be limited to values shown, and reduced for the possible effects of concentrated loads.
- Span ratings shall appear on all panels.
- Plywood edges shall have approved tongue-and-groove joints or shall be supported with blocking unless 1/4-inch minimum thickness underlay is installed or 1/2 inch of approved cellular or lightweight concrete is installed or unless finish floor is 1-inch nominal wood strip. Allowable uniform load based on deflection of 1/360 of span is 100 pounds per square foot.
- May be inches if nominal 1 inch wood strip finish floor is laid at right angles to joists.
Plywood roof sheathing shall be rated for Exposure 1, have a minimum nominal thickness of 19/32 inch (15 mm) and shall be continuous over two or more spans with face grain perpendicular to supports. Roof sheathing panels shall be provided with a minimum of 2-inch by 4-inch (51 mm by 102 mm) edgewise blocking at all horizontal panel joints with edge spacing in accordance with manufacturer's specifications, for a distance at least 4 feet (1219 mm) from each gable end. The allowable spans shall not exceed those set forth in Table 2322.2.3.
ALLOWABLE SPAN FOR PLYWOOD ROOF SHEATHING1
|MAXIMUM SPAN IF BLOCK|
OR OTHER EDGE
Exterior stud walls shall be sheathed to resist the racking load of wind as set forth in Section 1620 and the concentrated loads that result from hurricane-generated wind-borne debris as set forth in Section 1626 of this code and shall be, at a minimum, any of the following types:
- Tightly fitted, diagonally placed boards not less than 5/8- inch (17 mm) thickness, nailed with three 8d common nails to each support for 1-inch by 6-inch (25 mm by 152 mm) boards and four 8d common nails for 1-inch by 8-inch (25 mm by 203 mm) boards.
- Wall sheathing shall be plywood, or product approved structural panel, rated Exposure 1 with a minimum thickness of 19/32 inch (15 mm) and shall be applied to studs spaced not more than 16-inches (406 mm) on center. Wall sheathing shall be continuous over three or more supports and shall be nailed to such supports with 8d common nails. Nail spacing shall not exceed 6-inches (152 mm) on center at panel edges and all intermediate supports. Nail spacing shall be 4-inches (102 mm) on center at corner studs, in all cases.
- When plywood panel, or product approved structural panel sheathing is used, building paper and diagonal wall bracing can be omitted.
- When siding such as shingles nailed only to plywood or product approved structural panel sheathing, the panel shall be applied with face grain across studs.
Plywood, if protected with stucco, may serve for both sheathing and exterior cladding provided:
- The panel thickness shall be not less than 19/32 inch (15 mm) and Texture 1-11 panels, and the supporting studs shall be spaced not more than 16-inches (406 mm) on center.
- All joints shall be backed solidly with 2-inch (51 mm) nominal blocking or studs or the joints shall be lapped horizontally or otherwise watertight.
- Nailing shall be as set forth in Section 2322.3, Item 2.
Where storm sheathing is provided in accordance with Section 2322.3, exterior cladding may be one of the following:
- Wood siding shall be installed according to its product approval.
- Wood shingles or shakes attached to the storm sheathing, and/or to nailing boards or shingle backer securely attached to the storm sheathing. The minimum thickness of wood shingles or shakes between nailing boards shall be 3/8 inch (9.5 mm).
- Hardboard of siding quality for exterior use shall be applied in accordance with the product approval.