Tempo:
tie across the roof framing. Leave a 2 to 3 mm (1⁄8 in.) gap between panels to prevent buckling should expansion in the sheathing occur.
p. 287)—no less than 15.5 mm (5⁄8 in.)—is required for built-up roofing on a low-slope roof to be used as a walking deck.
The required thicknesses of the plywood, OSB or other roof sheathing are shown in Table 35 (p. 305). Sheathing thickness depends on the spacing of the rafters, roof joists or trusses and whether the edges of the sheets are supported. To prevent damage to the roof covering when thinner panels are used, support the joints with 38 × 38 mm (2 × 2 in. nominal) blocking nailed securely between the roof framing members, or by metal H-clips inserted between sheets. H-clips are widely used because installation is simple and economical.
Lumber sheathing must be laid closed, or edge to edge (Figure 98) with all ends supported and joints staggered. For exposure to high wind or earthquake forces, lumber sheathing must be laid diagonally or be engineered. The boards are usually 19 mm (¾ in. nominal) thick, but this thickness may be reduced to 17 mm (11⁄16 in.) where supports are spaced at 400 mm nominal (16 in. actual) or less on centre.
It is good practice to stagger the location of fasteners at the edges of adjoining panels. Staple fasteners for 9.5 mm (3⁄8 in.) roof sheathing must be at least 1.6 mm thick, 38.1 mm long with a 9.5 mm crown (1⁄16 in. thick, 11⁄2 in. long with a 3⁄8 in. crown), and be driven with the crown parallel to the framing (Table 38 on p. 307). Thicker roof sheathing (Table 22 on
Boards 184 mm (8 in. nominal) or less in width are nailed to the framing members with at least two, 51 mm (2 in.) nails per bearing. Those wider than 184 mm (8 in. nominal) should be nailed with at least three, 51 mm (2 in.) nails per bearing. For areas with high wind loads, the length of the nails must be increased to 63 mm (21⁄2 in.). Boards wider than 286 mm (12 in. nominal) should not be used for roof sheathing. For a wood shingle roof, the roof boards may be spaced
98 Installation of wood-board roof sheathing Spaced method nailing strip
Closed method roof boards joint
rafter ceiling joist plate Note: For areas exposed to high wind and earthquake forces, lumber roof sheathing must be installed diagonally.
p. 287)—no less than 15.5 mm (5⁄8 in.)—is required for built-up roofing on a low-slope roof to be used as a walking deck.
The required thicknesses of the plywood, OSB or other roof sheathing are shown in Table 35 (p. 305). Sheathing thickness depends on the spacing of the rafters, roof joists or trusses and whether the edges of the sheets are supported. To prevent damage to the roof covering when thinner panels are used, support the joints with 38 × 38 mm (2 × 2 in. nominal) blocking nailed securely between the roof framing members, or by metal H-clips inserted between sheets. H-clips are widely used because installation is simple and economical.
Lumber sheathing must be laid closed, or edge to edge (Figure 98) with all ends supported and joints staggered. For exposure to high wind or earthquake forces, lumber sheathing must be laid diagonally or be engineered. The boards are usually 19 mm (¾ in. nominal) thick, but this thickness may be reduced to 17 mm (11⁄16 in.) where supports are spaced at 400 mm nominal (16 in. actual) or less on centre.
It is good practice to stagger the location of fasteners at the edges of adjoining panels. Staple fasteners for 9.5 mm (3⁄8 in.) roof sheathing must be at least 1.6 mm thick, 38.1 mm long with a 9.5 mm crown (1⁄16 in. thick, 11⁄2 in. long with a 3⁄8 in. crown), and be driven with the crown parallel to the framing (Table 38 on p. 307). Thicker roof sheathing (Table 22 on
Boards 184 mm (8 in. nominal) or less in width are nailed to the framing members with at least two, 51 mm (2 in.) nails per bearing. Those wider than 184 mm (8 in. nominal) should be nailed with at least three, 51 mm (2 in.) nails per bearing. For areas with high wind loads, the length of the nails must be increased to 63 mm (21⁄2 in.). Boards wider than 286 mm (12 in. nominal) should not be used for roof sheathing. For a wood shingle roof, the roof boards may be spaced
98 Installation of wood-board roof sheathing Spaced method nailing strip
Closed method roof boards joint
rafter ceiling joist plate Note: For areas exposed to high wind and earthquake forces, lumber roof sheathing must be installed diagonally.
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