The Ultimate Guide to Types of Fasteners
Screws, bolts, and nails are some of the most vital parts of any construction project. These fasteners are used to hold together a wide range of materials, from plastic to cement. If you’ve ever walked into a hardware store and noticed a wall of nails and screws, you may have wondered why there are so many different kinds of fasteners, or maybe you wondered how to find the right one for your project.
The right fastener can make your work easier. It can also make your project safer, more durable, and more aesthetically pleasing. That’s why we’ve created this guide to fasteners and their uses.
Types of Screws
Screws are one of the most common types of fasteners used today. They’re distinguished from other fasteners by threading along their shank and a pointed tip. Screws are used in any situation where you need to join two or more pieces of material. Unlike bolts, the screw doesn’t need to extend through both pieces of material. Unlike nails, the threaded shank offers a little extra holding power.
Screws are commonly used for drywall, wood, roofing, and siding because of their versatility. Different types of screws are distinguished by several elements, including:
Picking the right type of screw for your job can speed up the project and make the finished product more durable.
Screws and Thread Type
Screws generally use one of two different types of threads. The first, known as a complementary thread, fastens to a pre-cut spherical groove in the screw hole. You’ll generally drill a threaded hole through the material first, then tighten the screw in place. Complementary threaded screws are usually used in harder material like siding, some plastics, and metals.
The second type of screw has sharper threads that drill into wood or plastic as the screw is tightened. These screws have different names depending on the manufacturer. Self-drilling, self-piercing, and self-tapping are all common ways to describe this type of screw. They’re usually used in softer material like wood and plastic. Self-drilling and complementary threaded screws have a variety of head shapes, drilling methods, and job purposes.
You may also see screws and bolts described by thread width. In general, machine screws and bolts have narrower threads that are closer together. Wood screws have more widely spaced threads.
Screws generally have different head styles:
- Flat. Flat heads have a countersunk head with a flat profile. They’re popular for finish work because the head is even with the surface it fastens. Most hinge and decorative screws have flat heads.
- Bugle. Bugle heads resemble countersunk flat heads, but the countersunk area curves into the shaft. The bugle head is used when it’s important for the screw to lie flat in the material, but pre-drilling holes isn’t efficient. Most drywall screws have bugle heads.
- Oval. Oval screw heads are countersunk screws with a slight curve above the surface of the material. They’re most often used in finish work.
- Round. Round screw heads extend above the surface of your material. The sides and top of these screws are rounded, with the drive style cut into the top of the screw. They are common for machine screws.
- Pan. The head of a pan screw sits above the material it fastens. They have a rounded base with a flat head. This type of head is common for machine screws.
- Truss or Mushroom Head. Truss screws can be distinguished by their extra wide top. The screw head is curved, similar to that of a round head screw. Truss heads are ideal for fastening thin material like sheet metal, insulation, or cabinetry. They have a lower profile than most round heads. These screws are often used to prevent tampering because of their low profile.
- Button. Button screw heads are a low profile type of non-countersunk screw. Because they’re not countersunk, they can be used in heavier materials than countersunk screws. The head is small and suitable for finished or decorative surfaces. Most button screws require a special driver.
- Cheese or Rounded Cheese. These screws have a round disk that sits above the surface of the material. Today, cheese head screws are uncommon. They’re used primarily in specialist jobs or when replacing screws in older materials.
- Knurled. Like cheese head screws, knurled screws are non-countersunk screws with a raised disk for the head. They may be relatively tall compared to the width of the head. Knurling refers to the crosshatched patterns on the side of the head, which makes them easy to tighten by hand. They’re sometimes referred to as thumb screws, and are used when materials need to be tightened and loosened regularly.
Screws are often sorted by head shape. The head shape refers to the top of the screw where the screwdriver or drill meets the surface.
Differently shaped heads usually require different tools for driving. Here are the common types:
- Slotted. This type of screw head is one of the most common and simple to use heads. The head has a single line cut into it, and any flathead screwdriver fits into it.
- Phillips. Phillips screw heads are the next most common type of screw head. These screws have a cross cut into the center of the head. The slot usually doesn’t extend across the entire head, so Philips head screws may need different sizes of screwdrivers.
- Combination. Combination screws can be fastened with either a flathead or Philips screwdriver. This drive type has a Philips head in the center of the screw. One line has the standard Philips shape, while the other is cut through the entire screw head, like that of a slotted screw.
- One Way. One way heads install with a standard Philips or flathead screwdriver. However, one side of the drive is cut and the other is sloped to prevent a standard driver from reversing the screw. These screws are often used in safes, gates, and public architecture. If you need to remove a one way screw, you’ll need a special tool.
- Square or Robertson. Square screw heads are also known as Robertson screw heads. They require a square screwdriver head for insertion. Although they’re less common than both Philips and slotted screws, the square head can be easier to insert into difficult holes because the square slot in the head reduces slippage and the possibility of wear and tear.
- Hex, Allen, or Socket. Hex screw heads, like square heads, are designed to reduce slippage. They also require special drivers to fasten them. Hex screw heads have a hexagonal indent on the screw head. You’ll generally need an Allen wrench to fasten them.
- Star or Torx. Star shaped heads are also known as torx heads. The six-pointed indents reduce the chance of stripping the head, and provide additional surface for tightening tension. You’ll need a torx head to fasten these screws.
Types of Bolts and Nuts
Bolts are designed for use in drilled holes or with nuts. They’re closely related to screws, so people often refer to bolts and screws interchangeably. Although bolts are also threaded, they don’t cut threads into the material to which they’re fastening the screws. Bolts are often used with nuts to fasten two materials together.
In many cases, bolts are used when the fastener needs to extend entirely through all materials being fastened. When the bolt extends through both surfaces, nuts are used to hold the join in place. However, not all bolts require nuts. Some bolts are placed deep in concrete or structural beams like screws.
Bolts are usually used when the materials need to withstand more pressure than screws will support. They’re also used when the materials being fastened need to withstand shear forces. The opposing pressures that come with shear forces can place more tension on fasteners. Thinner screws and nails may not be enough.
Head Styles for Bolt Fasteners
Compared to screws, bolts have relatively few head styles. Most bolts today are a variation of a hexagonal head, such as:
- Square Bolts. Square bolts have four-sided heads instead of the standard hexagonal head. Square heads were the standard bolt head before hex heads became popular. Today, square bolts are primarily used to match existing bolts in older architecture, or to create a rustic or old-fashioned look.
- Hex Bolts. Hex bolts are the standard bolt head used today. Hex bolts may be used with a washer to distribute weight more evenly. This is particularly common if the material is relatively thin or lightweight. Hex bolts sometimes have a slotted head as well, which allows them to be fastened with a wrench or a screwdriver.
- Carriage Bolts. Carriage bolts have rounded heads, and they are used primarily when fastening wood and metal. They usually have a small square section directly beneath the head to aid in fastening. Unlike other bolts, the shank directly beneath the head is usually smooth. This is followed by a threaded section at the bottom of the bolt.
- Lag Bolts. Lag bolts are some of the strongest bolts available. Because of their size and strength, they’re usually used to secure load bearing or structural elements of a building. Unlike other bolts, lag screws usually have a sharp point and wide wood threads. Although they resemble screws, lag bolts need a pre-drilled hole for fastening.
- Flange or Washer Bolts. Flange, or washer, bolts are used to distribute weight across a wider surface. They have a hex head with a round, flat surface directly beneath. A hex bolt with a washer serves the same purpose as a flange bolt. They do not require a separate washer.
Types of Fastener Nuts
Nuts are used with bolts to fasten materials together. The size of the nut must be matched to the size of the bolt. Like bolts, the majority of nuts today are hex shaped, so they can be fastened with the same sockets as the bolt themselves. Here are the various types:
- Hex. Hex nuts are the most common types of nuts. These six-sided nuts can be differentiated by size and height. Along with standard nuts, they are available in heavy hex nuts, which are stronger and wider, and jam nuts, which are a lower profile.
- Square. Square nuts are four-sided nuts used primarily with square bolts.
- Wing. Wing nuts have two large metal wings, which allow them to be hand tightened. They are primarily used when an item may need to be tightened or loosened by hand. They’re common in bicycles and furniture. They may also be found in tools and musical instruments, like drum sets.
- Nylock. Nylock nuts are also known as nylon insert nuts. They are available in standard heights and low profile, or jam, designs. The nylon insert prevents the nut from reversing without assistance.
- Cap or Acorn. Cap nuts have a round head that covers the end of the bolt. They’re used to prevent contact with the threads on the bolt. Acorn nuts, which have a higher dome than cap nuts, are often used decoratively.
Materials Used in Screws and Bolts
Most screws and bolts are made of steel. Bolts may be marked by the strength of the steel used. Nuts and screws, however, rarely have these markings. Common strength markings for steel include:
- Grade 2. This is the standard hardware grade, and these bolts are rarely marked.
- Grade 5 / Grade F. This type of hardened bolt is often used for automobiles. These bolts have three evenly spaced lines on the head of the bolt.
- Grade 8 / Grade G. This type of bolt is very hard and is commonly used for heavy duty applications. They have six evenly spaced lines on the head of the bolt.
Screws and bolts made of stainless steel are resistant to corrosion. If you need moderate resistance at a low price, look for stainless steel fasteners. Be aware that stainless steel cannot be hardened the same way that standard steels can be. If your screw or bolt will be load-bearing, consider using hardened steel instead.
Zinc coatings and galvanization are both designed to slow corrosion and prevent rust. Zinc plating provides moderate protection against corrosion. Hot dip coating leaves a thick layer of zinc on the fastener, and provides maximum protection.
Some screws and bolts may be chrome plated. Like other platings, chrome slows corrosion. These bolts are used primarily for aesthetic purposes because of the high cost.
Types of Nails
Nails are a popular type of fastener because they’re easy to find, inexpensive, and available in a variety of finishes. Nails can be fastened with nothing more than a hammer, so they’re used in a wide variety of projects. Nails are generally identified by job for which they’re used. The length, finish, and nail head differ according to their purpose.
Nails may also be identified by size or gauge. Although you may see nails listed by length or width, it’s more common to find them by penny. It’s an old fashioned system that refers to how many pence you would need to buy 100 nails of that size.
Small nails may be one inch long. They are usually called two penny, or 2d, nails. In general, the size of nail goes up by 1d for every ¼ inch longer the shaft of the nail, so a 1½ inch nail is also known as a four penny nail.
Like screws, nails are designed for a number of different purposes. It may be possible to use screws and nails interchangeably, but in some situations only a nail will suffice.
Small nails, like brads and tacks, have no equivalent among threaded fasteners. These tiny nails are designed for delicate projects where maintaining the integrity of the wood is essential.
Here are the different types of nails:
- Round Head Nails. Round headed nails are the most versatile of nail types. They have a small round head and a long shank. They’re an all-purpose nail suitable for a variety of tasks. The nail head may extend slightly from the surface of the wood.
- Finish Nails. Finish nails resemble round headed nails but have a smaller head area. The small head makes wood less likely to split. Once driven, these nails usually lie parallel with the wood. They’re often used when a cleaner or more finished appearance is required.
- Brad Nails. Brads resemble round or all-purpose nails. They’re distinguished primarily by their size, which is usually one inch or less. Seven eighths of an inch or one inch are common sizes for brad nails. Because of their small size, they’re less likely to split the wood they’re fastening. Brads are often used in cabinetry, for attaching plywood, or in paneling.
- Smooth Shank Nails. Smooth shank nails are used in a variety of projects. They’re easy to insert and to remove if necessary. Most all-purpose, finish, siding, and roofing nails have smooth shanks. Brads, some finish nails, and roofing nails may have a small ringed section near the head to prevent the nail from sliding out.
- Ring Shank Nails. Ring shank nails have a series of circular rings around the shank. These rings provide extra tension to prevent nails from sliding or loosening in the wood. Drywall nails and some siding nails have ring shanks to fasten materials together.
Different Nail Materials
In the past, many nails were made from iron. Today, most nails are made of stainless steel or copper. Here’s a description of each type of material:
- Steel Nails. Most nails are made from steel. This is a strong, durable material that’s relatively inexpensive. Most galvanized or coated nails are made from steel.
- Stainless Steel Nails. Stainless steel is another common material for nails. It’s used because it won’t corrode or break down.
- Copper Nails. Copper is another widely used material for all purpose, finish, and roofing nails. They are rust-resistant, so they’re the preferred material for roofing and siding nails. Many building codes require copper nails for roofs.
- Galvanized Nails. Galvanized nails are standard nails that have been coated in zinc. The zinc surface helps to prevent rust and corrosion in the nail. Although galvanized nails were the construction standard for many years, today copper nails are more common.
- Coated Nails. Some nails are also coated to increase their fastening ability. Most coated nails use either cement or vinyl coatings. Coated nails are usually used outdoors or in specialty applications.
Consider All Points Fasteners
If you’re looking for high-quality fasteners, check out our products today. We specialize in self-drilling screws for metalworkers, carports, and gutters. We also offer a wide variety of screws for roofing, fencing, and cabinetry specialists.