1. Apply APA RATED SHEATHING with a minimum Span Rating of 32/16 to roof framing spaced 24 inches o.c., or

2. Apply APA RATED SHEATHING with a minimum Span Rating of 24/16 to roof framing spaced 16 inches o.c.

3. Provide adequate ventilation. Meet or exceed your local code requirements for ventilation.

4. Fasten roof sheathing with 8d nails for panels 1 inch thick or less, 8d deformed shank or 10d common for thicker panels, or other code-approved fasteners. Space nails 6 inches at supported edges and 12 inches at intermediate supports. Recommended nail schedules for high wind zones are described in APA Data File, Roof Sheathing Fastening Schedules for Wind Uplift, Form T325, available from APA.

5. Leave a 1/8-inch space at all end and edge joints to allow for panel expansion.

Preframed Roof Panels

Spans of 8 to 12 feet are usually the most practical with preframed panel construction, although spans to 30 feet are not uncommon. Unsanded 4x8-foot APA panels with stiffeners preframed at 16 or 24 inches on center (Figure 22) are common. The long dimension of panel typically runs parallel to supports. Stiffeners and roof purlins provide support for all panel edges. Minimum nailing requirements for preframed panels are the same as for roof sheathing.

In preframed panels 8x8 feet or larger (Figure 23), the long panel dimension may run either parallel or perpendicular to stiffeners spaced 16 or 24 inches on center. Placing the long dimension across supports may require edge  support such as panels clips or cleats between stiffeners at midspan in accordance with Table 24. Recommendations in Table 27 on page 55 are based on long dimensions of the panel parallel to supports. Deflection limits are 1/180 of the span for total load; 1/240 for live load only. See Table 28 on the following page for design information on stiffeners for preframed panels. Nailing requirements for preframed panels are the same as for roof sheathing.

(a) For spans 48 inches or greater, space nails 6 inches at all supports.

(b) For stapling asphalt shingles to 5/16-inch and thicker panels, use staples with a 15/16-inch minimum crown width and a 1-inch leg length. space according to shingle manufacturer's recommendations.

(c) Use common smooth or deformed shank nails with panels to 1 inch thick. For 1-1/8-inch panels, use 8d ring-or screw-shank or 10d common smooth-shank nails.

(d) Other code-approved fasteners may be used.

(e) Fasteners shall be located a minimum 3/8 inch from panel edges.

Note: Cover sheathing as soon as possible with roofing felt
for extra protection against excessive moisture prior to roofing
application.

Note: For pitched roofs,place screened surface or side with
skid-resistant coating up it OSB panels are used. Keep roof
surface free of dirt, sawdust and debris, and wear skid-resistant
shoes when installing roof sheathing.

Note: For building with conventionally framed roofs (trusses or rafters),
limit the length of continuous sections of roof area to 80 feet
maximum during construction, to allow for accumulated expansion
in wet weather conditions. Omit roof sheathing panels in each course
of sheathing between sections, and install "fill in" panels  later to
complete roof deck installation prior to applying roofing.