FEMA P55 Coastal Construction Manual, Fourth Edition - Mad Cad

9 DESIGNING THE BUILDING Volume II
Figure 9-7.
Connection of the roof
sheathing to the roof
framing (Link #1)
is significantly greater than that provided by a smooth shank nail. Additional strength can be added by using
ring shank nails, also called deformed shank nails. The grooves and ridges along the shank act as wedges,
giving the nail more withdrawal strength than a typical smooth shank nail.
Fastener attachment requirements for roof sheathing to roof framing are available in building codes and
design standards and are presented in terms of nailing schedules dependent on nail diameter and length,
framing spacing, specific gravity of framing lumber, and wind speed. Common assumptions for calculating
nailing schedules to resist wind uplift are provided in Example 9.1. Minimum roof sheathing attachment
prescribed in building codes and reference prescriptive standards is 6 inches o.c. at panel edges and 12 inches
o.c. in the field of the panel.
EXAMPLE 9.1. ROOF SHEATHING NAIL SPACING FOR WIND UPLIFT
Given:
Find:
• Refer to Figure 9-7
• Wind speed = 150 mph (700-year wind speed, 3-sec gust), Exposure Category D
• Roof sheathing = 7/16-in. oriented strand board (OSB)
• Roof framing specific gravity, G = 0.42
• 8d common nail has withdrawal capacity of 66 lb/nail per the NDS
1. Nail spacing for the perimeter edge zone for rafter spacing of 16 in. o.c.
2. Nail spacing for the perimeter edge zone for rafter spacing of 24 in. o.c.
9-6 COASTAL CONSTRUCTION MANUAL