Nails are perhaps the oldest of all wood fasteners, having been utilized since ancient times for putting together wood structures of all sorts. Although there are now dozens of various types available, a lot are specialized designs with special industrial use. The most widely distributed varieties are the common nail, the finishing nail, the box nail, the large-headed roofing nail and the annular-threaded nail (also pertained to as screw nails).
Nails come in various lengths and in different gauges or sizes (body diameter). The common nail is used for approximate framing and universal construction work. It has a relatively large flat head and a diamond-shaped tip, and the shank normally has grooves under the head to help increase holding power. Box nails are like common nails, except that they are thinner in gauge and not quite as solid. These nails are useful for light construction projects where a heavy nail may tend to split the wood, and they are provided with either smooth or barbed shanks in various sizes.
When the look of nail heads on a finished project would prove unsightly, finishing nails are typically used. Finishing nails have small heads which can be readily punched down below the surface of the wood with a nail set. The holes which remain can then be filled up with putty. Finishing nails are usually used for adding up moldings and trim, as well as for assembling cabinets and similar projects. Professional carpenters generally use special casing nails on wood trim, instead of finishing nails. Though they look almost the same, casing nails contain slightly heavier shanks to give increased holding power.
Small finishing nails, which measure anywhere from one half to one and a half inches in length are commonly referred to as brads, instead of nails. They’re marked by length and wire gauge number, and are valuable for fine work where little or no stress is involved. When this same type of thin-gauge, light-duty nail is designed with a flat head, it is pertained to as a wire nail, rather than as a common or box nail.
Large-headed roofing nails are typically galvanized to resist rusting. As the name connotes, these nails are used for nailing down roof shingles and asphalt-type roll roofing. Lengths differ from 1 to 2 inches, with head diameters varying consequently. Since they have a sort of heavy shank (in proportion to length), they’re seldom utilized for nailing in thin lumber because they’ll very likely cause splitting.
A relatively recent addition to the modern family of nails is the annular-threaded, or screw nail. Though it is driven in using a hammer— just like any other nail—it has holding power like that of a wood screw. Available in aluminum or steel and in diverse sizes, this nail also lessens the danger of splitting up in any type of wood. Though the cost per pound might be more than twice that of the same size common nail, threaded nails could actually cost less on a per-nail basis. There are ordinarily more nails per pound (the grooved shank on every nail weighs less than the smooth, solid equivalent of a common nail) and, since the nails have much greater holding power, lesser nails are needed—or a smaller size can be used—on whatever given job.
Oxford English Dictionary (2nd ed.)