sheet metal / self-tapping screw withdrawal in wood 1

[WilliamHR]

I'm dealing with the connection of a cold formed steel track to a wood-framed roof, and can't fild withdrawal values for sheet metal screws in wood. Any ideas?

 

[hokie66]

Use screws designed for wood. The threads on metal screws are too fine for wood and are not reliable fasteners in wood. That's why you don't find values.

 

[WilliamHR]

Really? the US dept of Ag says the capacity should be "about 10% greater than that for wood screws of comparable diameter and length of threaded portion" (Encyclopedia of Wood, p. 7-10), but self-tapping screws are not covered under NDS, so I was looking for design values elsewhere...

 

[hydtools]

Here is a paper that shows little to no difference for pullout:

http://www.grabberman.com/Media/TechnicalData/452.pdf

Ted