A roofing nail is, as the name implies, a nail used for installing roofing. There are, however, many types of nails referred to as roofing nails, and these nails have many other uses. The main feature that distinguishes a roofing nail is its large head, which is usually much larger and flatter than other types of nails. This permits the nail to hold down roofing felt and roofing shingles without tearing through the material. Roofing nails generally come in lengths of 1 to 1.75 inches (2.54 to 4.44 cm), although shorter and longer nails can be found.
One element that makes roofing nails unique is the material they are made of. These nails are almost always made of galvanized iron or aluminum. Galvanization adds a thin layer of steel or zinc to an iron nail that prevents it from rusting; aluminum is used for the same reason. Roofing nails must stand up to years of rain, snow, and other weather. Rusting is undesirable not only because it will shorten the life of the nail, but because it can cause unsightly stains on a roof.
The large, flat head on a roofing nail, in addition to helping to hold down roofing materials, also helps prevent water from seeping in. Some roofing nails have a small rubber or plastic washer under the head. This adds another layer of waterproofing to the nail.
Many roofing nails are available with short threads or a spiral shank. These features assist in grabbing the wood sheathing that is usually installed under the roofing materials and helps prevent the nail from popping out or becoming loose. Missing and loose nails can cause roofing materials to come off or to leak.
Coil roofing nails are made to fit a nail gun. These nails come in all the variations listed above, but are mounted in a coil that feeds into the nail gun. This allows for a much faster installation process with less labor. Roofing nail coils are made to fit all brand names of nail guns and often come in standard coils of 120 nails.
The large head and water resistant features make a roofing nail a common choice for other construction projects. They are good for installing water resistant drywall and tile backer board in bathrooms. The nails will not rust and the large heads will usually not break through the paper or fiberglass mesh surface of these boards. They are also often used for installing metal lath in areas to receive mortar products.