Screws are extremely useful in construction and other industries — they provide secure, tight fastening and are easy to adjust and remove, making them a suitable choice for many jobs. These fasteners come in so many types, materials and sizes that choosing the right screw for your project involves a few considerations.
Below, we’ll walk you through all the different types of screws and provide tips on how to choose the right screw size and length.
Types of Screws
To handle a construction job efficiently and safely, you need more than the proper tools — you also need the right fastener. Screws are excellent for bringing materials together, but there are many types available, each of which is best suited for a specific job. You can consider screws in two categories — general and specialized.
General Screw Types
When choosing screws, you might start with the general fastener category. These screw types suit various projects and include:
Wood screws: Wood screws have sharp points and are used to fasten two pieces of non-structural wood together. The threads on these screws are coarse and feature an unthreaded shank next to the head. This unthreaded portion allows the wood screw to bring the two pieces of wood tightly together.
Drywall screws: These screws are threaded fully and designed for interior jobs like fastening drywall to studs. Drywall screws with coarse threads are meant to attach drywall to wood studs, while ones with fine threads are for securing drywall to metal studs.
Cement board screws: This fully threaded screw type is designed to fasten a subfloor for tiling jobs or backboard to studs on a wall. They feature a coating that provides resistance to corrosion, which can be caused by moisture or mortar. Cement board screws can work with metal, wood or both.
Deck screws: These screws are used for fencing, decks and other jobs outside. When choosing deck screws, keep in mind there are two common types. Wood deck screws have a coarse-threaded portion and unthreaded shank, and composite deck screws feature a smaller head and finer threads. Some composite deck screws feature an additional thread set to prevent the composite materials from mounding at the screw’s head.
Structural wood screws: A structural wood screw shares the same basic design as a normal wood screw with an unthreaded shaft and coarse threads. But these screws are considerably stronger. You can also use them like lag bolts or screws if the local building codes allow it.
Lag bolts or lag screws: A lag screw or bolt fastens heavy components or materials that handle heavy loads. They feature hex heads, meaning you need a socket and ratchet or wrench to install them. Eye lag screws are also common, which are wood screws that have rings on their head to secure a chain or rope.
Machine screws: These completely threaded screws are designed to fasten together metal components. There are several kinds of machine screws, including socket cap screws, which feature cylindrical, raised, hex-socket heads, and socket set screws with no heads but rather internal hex sockets.
Concrete screws: A concrete screw is made to fasten in masonry, such as concrete. Self-tapping concrete screws are available, which you can drive into a material directly without the need for pre-drilling. There are also types available that work with masonry anchors.
Sheet metal screw: These completely threaded screws are used to secure two pieces of sheet metal or sheet metal with softer materials. This screw type is often available to use with a pre-drilled hole. There are also sheet metal screws that come with self-drilling points.
Multi-material screws: A multi-material screw includes features for use in sheet metal, wood, masonry, drywall, plastic and various other materials.
Other than the common screw types above, there are several different kinds of screws available, most of which have specific applications. These include:
Ceiling fan screws: This screw type fastens the light globes or blades of ceiling fans.
Cabinet mounting screws: These screws are specifically designed for fastening cabinets to wall studs.
Gutter screws: This screw type fastens the components of a gutter together and also fastens the gutters to the sides of a house.
Dowel screws: This headless screw has threads and points on both of its ends. It is designed to attach wood pieces together with no visible fasteners.
Landscape screws: These long screws are used to connect landscape timbers.
Wall plate screws: This machine screw fastens the covers for outlets, light switches and other similar components over an electrical box.
Trim screws: A trim screw features a tiny countersinking head, allowing it to be easily concealed.
Security screws: Security screws are designed to be difficult to remove. Doing so requires a specialty bit or driver.
Screw Finish and Material
Material and finishes are two important characteristics of a screw and often determine what jobs the fastener is suitable for. While some materials allow a screw to handle demanding jobs, others help prevent corroding or rusting. If the screw’s material is prone to rust, certain finishes can protect it from corrosion.
The most popular screw material is steel, but steel experiences corrosion when exposed to moisture. For this reason, a steel screw requires a plating or coating that’s resistant to corrosion. Popular finishes and coatings include black phosphate and zinc-plating.
A variety of other finishes are available, including polymer, electro-coated paint, powder-coated paint and ceramic that help prevent a steel screw from corroding. Decorative finishes like chrome, nickel plating and brass feature some protection against corrosion, but they are not recommended for outdoor applications. Bright steel screws do not have any corrosion resistance and are designed solely for interior applications, where moisture isn’t an issue.
Other common screw materials include:
Note that some finishes and materials aren’t compatible with certain tasks and needs. Fasteners are often made for very specific applications and don’t work with other ones. Remember to read the manufacturer’s instructions and abide by code specifications.
Types of Screw Drives
Screws feature a number of drive types, with the most common being:
Phillips and slotted drives: Phillips and slotted drives are two of the most common, although screw heads with these drives tend to easily cam out. There are also combination drives, which work with both types of drivers.
Allen drives: Screws with Allen drives feature sockets with six sides but also are susceptible to camming out.
Square and star drives: Square and star drives, alternatively known as Robertson drives and Torx, respectively, reduce the risk of camming out. These drives are excellent at gripping the driver and, in many applications, allow one-handed driving.
Hex head: Screws with hex heads are driven in using a socket and ratchet or wrench.
Types of Screw Threads
If a screw has coarse threads, there is more space between the threads. These fasteners tend to work with softer materials, such as drywall or wood, although sheet metal screws feature coarse threads, as well. You can install and remove screws with coarse threads rather quickly.
If a screw has fine threads, it’s most likely meant to be used with nuts or for pre-tapped holes. The smaller gaps between each thread provide the screws with a tighter hold, although installing and removing them takes more time.
Types of Screw Heads
The heads of screws also come in various types and serve different purposes. Some heads fit shallow depressions known as countersunk holes. Other heads, such as those of bugle-head and flat-head screws, are designed to rest flush with the workpiece’s surface. There are also self-countersinking screws, which cut the countersunk hole while you’re driving them.
Other than countersunk screw varieties, there are non-countersunk screws with pan or round heads to sit on the workpiece’s surface. There are also trim-head screws with tiny heads, which means you can conceal them more easily than other fasteners. Screws featuring washer heads, wafer heads and truss heads provide a larger area of contact underneath the head of the screw than other types of fasteners.
How to Choose the Right Screw for Your Project
With the most common types of fasteners in mind, it’s time to decide how to choose a screw for your project. To make the right selection, follow these tips:
Pick a drive style: As you learned above, there are many different drive styles of screws, including Phillips, flat head, torque and square. Torque and square heads, for example, will make it easier for your drill bits to stay in place and help prevent stripping and slipping.
Pick a size: Pick a screw thickness suitable for both the weight the screw must support as well as the width of the material you’re inserting the screw into.
Figure out the right length: When choosing screw length, pick a length based on how deep the material is you’re inserting the screw into. When measuring the screw, measure from underneath the head of the screw to the point. Once again, you should consider how much weight the screw will have to support.
With the right fastener choice, you can have better success with your project. You’ll be able to work efficiently and avoid having to start your project over.
What Is the Nature of Your Project?
Each screw type is designed to serve a specific purpose. When choosing screws, you’ll need to know what type of project or projects you’ll be taking on and what materials you’ll be using. Screws are first categorized based on the materials on which you can use them. The most commonly used screw types include:
Wood screws: These fairly coarse screws feature relatively large spaces between threads. Large versions of wood screws also have an unthreaded shank next to the head. Some wood screws also feature a subtle taper from head to tip. Woodworking and other wood-based projects could benefit from these fasteners. Wood screws are not case hardened so they are softer than case hardened screws.
Drywall screws: Drywall screws are characterized by the easily noticeable curve on the junction that connects the shaft to the head called a bugle head. This curve keeps the drywall from tearing when the screw is inserted. Both fine- and coarse-threaded drywall screws are available. The coarse-threaded versions are meant for securing drywall to wood shafts, and the fine-threaded ones are used to connect drywall with metal shafts. Consider the nature of your building project to choose the right drywall screws.
Sheet metal screws: Sheet metal screws tend to feature threads all the way from the head to the tip, meaning the threading is not interrupted. Some feature self-drilling or self-tapping tips, which is particularly helpful if you haven’t made any drill holes. Construction, roofing and HVAC industries may use these fastener types. Sheet metal screws are case hardened for additional strength.
Remember, a variety of screw types exist in general and specialized categories. Your job site may require a few different styles to complete your tasks.
How to Choose the Right Screw Size
Once you’ve narrowed down the right screw type for your project, you’ll need to determine the appropriate size. Screw size includes both the fastener’s length and width.
When looking at screw sizes, you may see the word “gauge,” which refers to the width or diameter of a screw. Screw gauges commonly range between 2 and 16, with 8-gauges being a good general-purpose size. If you’re working with particularly heavy materials, you’ll want to use a 12-gauge or 14-gauge screw, and for finer applications like woodworking, you may not need anything more than a 6-gauge.
To understand how to choose a screw size, have the drive style you want in mind and follow these steps:
Pick the screw gauge: The gauge you choose will partly depend on how wide the material you’re screwing into is as well as the weight the screw must support. Thicker screws will support more weight, but they also must be anchored in more material.
Pick the screw length: Ideally, you should choose a fastener that’s about half as long as the material it’s going into. If the screw is less than half the length of the receiving material, it won’t anchor properly. If you pick a screw that’s much longer than half, you may damage the other side of the material.