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Component Manufacturing dverti$er
Don’t Forget! You Saw it in the
Adverti$er
October 2018 #10231 Page #108
Still Using Lag Screws? Consider Self-Tapping Wood Screws Instead By Aram Khachadourian, P.E.
ag screws are traditionally specified for many structural loads in wood construction. However, recent innovations in engineering for self-tapping wood screws have made them an increasingly popular, labor-saving alternative to lag screws. In the following, Aram Khachadourian, P.E., of Simpson StrongTie discusses the structural and economic advantages of this option.
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In the past several years, there’s been an increase in the use of screws in applications that have traditionally been reserved for lag screws. Innovation in screw design has fueled this shift. Proprietary self-tapping wood screws now offer many benefits in comparison to commodity lag screws. Lag screws have been used for decades and not much has changed over that time. Newlin and Gahagan published the paper “Lag-Screw Joints: Their Behavior and Design” back in 1938. This paper describes their research into a variety of lag screws purchased from local hardware stores. They developed the predrilling requirements and derived the basic equations for determining withdrawal and lateral load resistance that are still being used today. The paper was published by the US Department of Agriculture and was available for 10 cents a copy. The technology behind proprietary screws, however, has moved beyond that Depression-era approach.
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