Everybody can relate to the frustration of stripping out a fastener; one can try to tighten it but gets nowhere fast. Sometimes, the head of a screw will even break off completely. There is a reason for this, and it isn't by coincidence that some strip out, while others perform like a champ.
At a glance, almost every fastener looks the same. However, there are a few key distinctions when you look at them more closely. For example, the above-mentioned fastener failures can be caused by poor material selection, an inferior hardening process, and a host of other design flaws. You probably didn't think fasteners required much engineering but in fact, they do-at least premium quality fasteners.
Whether selecting screws, bolts, biscuits or nails, it usually pays to consider the features and benefits of a premium quality fastener. Poor fastener quality selection will only lead to poor craftsmanship. It may not always be necessary to use the best fasteners but when working in residential and commercial construction, and industrial settings, most professionals know that it pays in the long run to buy premium quality fasteners from the outset. Otherwise, they may have to go back and do it a second time.
Even worse, the structure may fail when extreme conditions test the structural performance of a home or building. The peace of mind alone is worth the minimal investment of buying the right fastener.
The anatomy of a nail
It goes without saying that a nail has three major components: the head, shank and point. Hardly anyone ever asks what each of these three components do. Distinctions in the point determine the ease of which a nail drives into material. It also contributes to the difficulty involved with pulling it out later.Secondly, the shank's length, diameter, stiffness and surface geometry play crucial roles in resisting pull out (withdrawal) and push over (shear). Finally, the head size at the connection surface holds material in place while preventing it from pulling through. The way these three components work together will determine how well the connection performs in its intended application.
The stakes can get much higher with nails because they are overwhelmingly the choice of fastener for critical structural connections in our lives. For example, those that live in Miami are probably more interested in a stronger connection for their roof. Weather plays a much larger role in fastener selection in coastal states, such as Florida. Meteorologists forecast a natural cycle of heightened hurricane activity for the next five to 10 years. There is more than an 80 percent chance that at least one major hurricane will strike the United States in 2006 and a 64 percent chance of it hitting Florida.
According to the Insurance Information Institute research, insured losses from the 2004 hurricane season are estimated at $18.8 billion ($22.9 billion including liability claims). In terms of property damage, this ranks above the 9/11 terrorist attacks as the most costly catastrophe in U.S. history. The same goes for California, except the threat of earthquakes loom over the West Coast rather than impending hurricane conditions.
Most wood frame construction tends to fail at the fastening point, which is why a nail design is so critical to structural integrity. An example of the proper fastener in these regions is the HurriQuake disaster-resistant fastener, manufactured by Stanley-Bostitch. This nail was engineered to withstand two very different types of destructive forces-uplift and shear. These forces contribute to the majority of structural damage during hurricanes and earthquakes.
Let the winds blow
When high winds pass over the roof of a house, a suction force (called uplift) is created that tends to pull the roof up and off of the house. A nail with a 30 percent larger head diameter and aggressive ring shank geometry should produce an increase in resisting the vacuum effect of uplift forces, which often cause standard nail heads to pull or tear through sheathing.Earthquakes are an altogether different type of structural force and create shear forces that shift a home from side to side. This explains why damaged structures sometimes droop or lean after earthquakes. Performance improvements are made from a combination of several factors: an oversized head, a 50/50 shank technology, an aggressive ring shank and a high-quality carbon steel alloy. In combination, these features lead to a dramatic increase in resistance to earthquake type forces of up to 20 percent.
Determining the correct fastener for a connection is often not given a lot of thought but can make a big difference in the quality and long-term sustainability of a structure. Fasteners play a key role in holding everything together. The above-mentioned example illustrates how fasteners change the performance of critical connections without excessive cost. Careful consideration of the appropriate fastener will always result in better craftsmanship. That's what reputations are built on.
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