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Screws in Plywood for Seismic/Wind Loads

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An excerpt from ATC/SEAOC's 1999 "The Path to Quality in Seismic Design and

"Some very limited testing has been performed on use of wood screws to
fasten sheathing to wood framing. One test used commonly available
cut-thread wood screws where the tranisition from the solid shank portion of
the shaft to the threads occurred at the back face of the sheathing, which
is common for screws with a diameter to 8d or 10d nails. This configuration
exhibited very little ability to withstand cycled loading. It is recommended
that the total screw length be increased so that the screw thread to solid
shank transition occurs well inside the stud member. Behavior of sheathing
attached using rolled-thread screws is currently not available, however, and
there are legitimate concerns regarding the ductility of screws in these


Fred Turner, Staff Structural Engineer, California Seismic Safety
Commission, 1755 Creekside Oaks Drive Suite 100, Sacramento, CA 95833
916-263-0582 Work Phone, 916-263-0594 Fax fturner(--nospam--at)