While nails are most often used for fastening wood, they can also be used to fasten materials to concrete, masonry, or metals. This article provides information on nail size, shape, and use.

Nail Composition

Nails are used to fasten two materials together using friction. Made of metal, nails are either cut from a flat stock or pulled from a round wire.

The head of the nail is enlarged and flattened to allow for easy hammering. Various shapes are used depending on the type of materials being fastened and the intended appearance.

The shank is the long slender portion of the nail. Nails hold materials together through the friction created between the shank and the material. Shanks may have threads or grooves to help increase friction. Shanks are generally round or elliptical, but are also sometimes square or rectangular.

The nail point is the tapered portion at the end of the shank that wedges a material apart to allow the nail to be driven into the material. Nail points are round point, diamond point (shown at left), or chisel point.

Nail Sizes

The size of nails is measured in pennies, with the symbol "d". As nails get longer, the diameter of the wire generally becomes larger as well. Nails longer than 6" are usually referred to as spikes.

Size (penny)Length (inches)
3d1 1/4"
4d1 1/2"
5d1 3/4"
7d2 1/4"
8d2 1/2"
9d2 3/4"
12d3 1/4"
16d3 1/2"
30d4 1/2"
50d5 1/2"

Nail Types

Common Nail

Large, flat head; general use nail
Box Nail

Large, flat head; thinner shank than common nail
Casing Nail

Small, conical head; thin shank; used where head is driven flush and remains visible
Finishing Nail

Small barrel head; thin shank; meant to be driven below the surface and covered with putty; head may have a dimple to accept a nail set
Cut Nail or Cut Flooring Nail

Tapered, rectangular shank; blunt tip to prevent splitting

A smaller version of a finishing nail
Drywall Nail

Large, flat head; shank is usually grooved with concentric rings
Concrete Nail or Masonry Nail

Flat head; grooved or fluted shank; hardened steel; sometimes has a diamond point
Roofing Nail

Very large, flat head; short shank;
sometimes grooved
Duplex Nail, Form Nail, or Scaffold Nail

Two flat heads; prevents nail from being driven flush, which allows easy removal
Spiral Nail or Screw Nail

Flat head; spiral shank;
rotates like a screw when driven

Nail Coatings

While many nails come without a special coating, there are some common coatings that are used regularly.

Hot-dipped Galvanized coatings provide a resistance to rust. Galvanized nails should be used where moisture may cause deterioration of the fastener. In addition, galvanized nails are recommended for pressure-treated wood because copper is part of the treatment; due to galvanic action, the copper would corrode metal nails without the zinc coating.

Vinyl coatings serve two purposes. First, the vinyl makes the nail easier to drive by reducing friction. However, the friction still generates enough heat, which leads to the second purpose. When driven, the vinyl melts. After cooling, the vinyl is adhered to the nail and the wood, which makes it harder to remove. The vinyl coating is usually green or yellow.

While not a coating, stainless steel nails resist corrosion. However, they are more expensive than coated nails.

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