August 2003
Executive Summary
Proper attachment of structural sheathing to the roof framing is a critical step in building a wind
resistant structure. Inadequate fastening of roof sheathing panels is one of the primary causes of
damage to light-frame wood construction during high-wind events such as hurricanes and
tornados. The current guidelines for placement of sheathing fasteners when used with 2x lumber
imply the degree of accuracy that is impractical for typical construction methods. Although it is
reasonable to assume that some amount of variance from these guidelines is allowed, no
approved or validated range of tolerances have been established.
The following are standard
specifications for installing wood structural sheathing panels:
- minimum 1/8-inch gap between panel edges;
- 3/8-inch minimum edge distance;
- fastener head flush with sheathing surface; and,
- specified nail spacing (e.g., 6 inches on center).
This study addresses the need for practical roof sheathing nailing tolerances. These tolerances
will allow for moderate errors in nail placement without compromising the intended strength of
the sheathing connection. This testing plan was developed to establish tolerance limits for:
- nail edge distance;
- nail spacing ; and,
- nail overdrive.
The tests conducted in this research demonstrate that slight nailing discrepancies have little
affect on sheathing connection capacities. Nailing tolerances, which allow for practical degrees
of variation, were developed from the findings of this study for nail diameters of 0.131” or less
and sheathing thickness of 7/16” or greater.
Prepared for:
U.S. Department of Housing and Urban Development
Washington, DC
Prepared by:
NAHB Research Center
Upper Marlboro, MD
46 pages
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