Screws are used to secure two surfaces together, and they’re one of the most commonly used types of fasteners. But with a whole universe of screws designed for different purposes out there, it can be hard to decide which type is the one you need for your project, and in this post, we’ll go through all the types of screws according to their anatomy and usage.
From wood screws to metal, drywall, masonry, and security screws, they may look rather similar, but they’re definitely not interchangeable.
Using the right fastener can have a huge impact on your work. In this guide, we’ll teach you how to match the screw to the material and help you identify which type of screw is best for your project.
Anatomy of a Screw
Even if you’ve used plenty of screws before, you may be unfamiliar with the terms for their different parts.
As you’ll be able to see by the end of this article, there are many different types of screws. They all are, however, comprised of a few similar parts. Getting to know these parts can help you make a decision as to which type of screw meets your exact needs the best.
These are the different parts of a screw:
The head is the top section of the screw, where the drive is. There are two basic screw head types: countersunk and non-countersunk or traditional, both of which include various unique drive designs. The head shape or style does serve not only a functional purpose but also a decorative one.
Countersunk heads sit flush against the surface in which they’re driven, with little or no protruding parts. Traditional screw heads, on the other hand, do protrude out of the surface into which they’re driven.
The drive is the shape of the slot where the tip of your screwdriver goes. To drive a screw into a surface, you have to press the screwdriver into this notch and turn it several times.
There are many types of drive shapes, but the most common ones are cross-head, slotted, square, star, and hex socket.
The shank is usually the unthreaded or smooth section between the head and the thread of the screw. Wood screws, for example, have an unthreaded shank to ensure a stronger hold. There are other types of screws, though, that have a fully threaded shank, which means they lack this smooth section because the thread goes from the head all the way down to the tip.
The thread is the section of the screw that contains helical ridges and removes material from the surface into which it’s driven.
Threading has many components that can vary among screws. These include the shape of the thread, its angle, and the size of the pitch, which is the distance between the crests of each thread. They can all have a significant impact on the performance and applications of the screw.
The tip is the endpoint of the screw, which enters the material into which it’s driven. Most tips are usually sharp and pointed to be able to penetrate the surface easily. If there’s no tip (i.e., if it’s a flat tip), what you have is a bolt, which requires a pre-made hole to be driven into a surface.
If you’ve been looking around online, you might’ve seen that some people mention over 30 different types of screws. The truth is that they’re actually describing the different types of screw heads and every subtype there is.
Below you’ll find a group of the most common types of screws, along with their applications and main features.
Types of Wood Screws
Wood screws are, as their name suggests, used to join two pieces of wood together, and they’re probably the most common type of screw and the most popular one among handymen and DIYers. They’re commonly made of bronze or stainless steel, and they’re available in both interior and exterior styles.
With a smooth shank, coarse threads, and tapered point, they’re very easy to identify. However, this design serves another purpose: it helps the screw dig smoothly through the wood fibers, minimizing resistance and drastically reducing splintering.
You’ll find that wood screws are relatively inexpensive and that they come in a wide variety of diameters and head shapes, the most common of which are flat and round heads. Round-head wood screws are best suited for attaching thin materials to wood. They’re the most visible of the two, which is why they’re used for decorative purposes. Flat-head wood screws, on the other hand, are ideal for securing hinges and when your project requires that the screws remain hidden or sitting flush against the wood surface.
If you’re looking to buy a set of wood screws, we recommend getting #8 screws (like these ones here), they’re the standard and good enough for most wood projects. Always bear in mind that you’ll need to select a length that will penetrate ⅔ or half the thickness of the bottom material.
Medium Density Fiberboard (MDF) is a material commonly found in interior trim, bookcases, and shelves. Since it’s harder than solid wood, regular wood screws will end up splitting when trying to pierce MDF. Moreover, they’re too big and can damage delicate trim.
While you can drill a pilot hole to work with regular wood screws, self-tapping MDF screws can make your life easier and help your project go quicker.
MDF screws have star-drive heads designed to minimize splitting when piercing the material.
Decking screws are, quite obviously, meant to fasten decking, or “deck flooring,” to the deck frame. However, they can be used for many other outdoor projects like building outdoor furniture such as wooden chairs, planters, and window boxes because they’re made from stainless steel or carbon steel to resist corrosion and withstand exposure to the elements.
These screws are similar to wood screws in that they have coarse threads and a smooth upper shank and are designed to resist rust and corrosion. The difference lies in that decking screws have a larger surface area that allows them to bear larger loads.
The decking screw heads are manufactured to countersink and sit flush against the surface so that there aren’t nail tops left above that you can trip on while walking across the deck. They also have a unique notched point that’s optimal for removing wood chips.
Most decking screws are self-tapping and come in both Philips and star-drive heads, the latter of which minimizes the risk of stripping the screw.
If you’re installing composite decking, you need decking-rated screws. For pressure-treated wood, you should only use ACQ-compatible decking screws.
Types of Metal Screws
Metal is a very hard material that requires special fasteners. Sheet metal screws have sharp tips and a fine, sharp thread along the whole shaft. The full threads help increase retention between materials, and the sharpness of the threads and the tip allows the screw to cut easily through the metal.
Sheet metal screws are mainly designed to attach and secure metal parts to each other. However, they’re more versatile than that, as they can also be used to fasten metal pieces to other items like plastic, rubber, or wood.
This type of screw is available in many types and sizes, depending on the material it’s going to be driven into. There are two basic types of sheet metal screws: self-tapping and self-drilling. While self-tapping screws require a pre-drilled or pre-punched hole to fasten thin sheet metal, self-drilling screws have a very sharp drill point tip that allows them to dig through various gauges of metal materials without a pre-drilled hole.
As regards head shapes, you can find flat, hex, and round, and they’re typically made from pure steel with a weatherproof coating of stainless steel or aluminum.
The Hillman #7 x ½” Hex Washer-Head self-drilling sheet metal screws are great for most repairs around the house.
Machine screws are much stronger than standard screws, as they’re used in machining applications in industries to hold heavy-duty metal objects such as machine parts together.
These screws have a blunt end rather than a sharp tip, and they’re specifically designed to fasten to a tapped hole on a surface with the help of a nut. For this reason, when you’re buying machine screws, you need to make sure that the threads in the nuts match those on the screws.
Speaking of threads, machine screws have finer and more precise threads than other types of screws, and they’re available in almost every material, including stainless steel, carbon steel, brass, and even nylon.
The Knob and Pull #8 -32 x 1 ½” screws are a bestseller for DIY projects around the house like fencing, cabinet making, framing, and more.
Other Types of Screws
As you can probably guess, drywall screws are used to join drywall panels directly to wood or metal studs. They provide a stronger hold than drywall nails and can easily penetrate the material without tearing, thanks to the coarse thread and super-sharp flat tip they have. Because drywall screws are designed for countersinking just below the surface o of the material, they’re very easy to conceal.
As with the previous screw types, there are many available options when it comes to drywall screws, including those that are coated with zinc or phosphate to reduce corrosion. The two main types of drywall screws are coarsely-threaded (W-type screws) and finely-threaded (S-type screws).
W-type screws are used to fix drywall to wood studs. They feature widely arranged threads designed to effectively grip into the wood and an extra sharp tip with a phosphate finish to penetrate the material easily. S-type drywall screws are meant to attach metal studs to the drywall panel. They have double threads and a self-drilling tip for an issue-free start.
Because they’re cheaper than wood screws, some people try to use them in woodworking projects. We don’t recommend doing that because of their brittle nature. Drywall screws are very thin and prone to snap if you’re driving them into hardwood.
If you plan on replacing your drywall panels, we suggest buying 1-1/4-in. #6 drywall screws if you’re attaching standard ½-inch-thick drywall to wood studs (you can find a nice fine-thread drywall screw assortment here). When fixing standard ⅝-inch-thick drywall panels to ceilings studs, you need to use 1-5/8-in. coarse-thread drywall screws. The reason why we recommend these screw lengths is to provide a strong and secure hold by ensuring that the screw sinks completely through the material and at least into half the thickness of a standard stud.
When you need to attach wooden floor plates to your basement floor or concrete foundation, you need to use masonry screws. Also called “anchors,” these fasteners are designed for fixing wood or metal to concrete, mortar joints, and brick.
They have a flat tip, which makes them unable to bore their own hole as they’re driven into a surface. Therefore, you must drill a pilot hole (a small, pre-drilled hole) before you can insert the masonry screw. To create this hole, you’re going to need a hammer drill and a carbide masonry bit that’s usually sold separately.
Masonry screws come in two common head types: a flat head or a slotted hex head. Flat-headed screws are ideal for countersinking, and they can be flush against the surface of the material they’re driven into for a nicer look. Slotted hex heads are easier to drive in, but they require specific hex-head bits that match. You can find the information about the type of bit and size that you need to drive them into the material.
For attaching wood or metal to concrete, these Confast 3/8″ x 3″-inches work really well. They have a hex head, so you’re going to need an appropriate drill bit to make the pilot hole.
Multi-purpose or production screws are definitely one of our favorites. They’re made of hardened steel, which makes them incredibly strong and versatile enough to be used in a wide variety of projects.
These screws come in star or square drives to reduce the possibility of cam out. They also have self-drilling points, so you can avoid the extra time that drilling pilot holes require. However, the pilot hole will still be necessary to prevent splitting when you’re working near the end of a board.
Their only downside is that they can be expensive, more so than regular wood screws, for example. However, we recommend avid DIYers the investment and to keep a set around because you’re definitely going to need them.
While lag screws are not as common as any of the other types of screws, they’re worth mentioning because they’re extremely sturdy and some of the toughest and durable fasteners out there. They’re typically used to connect heavy materials that need to bear large loads.
Lag screws have a high-carbon steel core that’s coated with galvanized zinc to protect them against rust and corrosion. They’re threaded all the way up the shaft and only available with hex heads that are manufactured to withstand a lot of torque. You’ll need to drill a pilot hole to install them, so using the right driver bit and a power drill are essential to tighten the screws.
Security screws are also known as tamper-proof screws because they’re crafted to protect against removal or tampering. They’re more or less like standard screws, only they have a unique head that common tools can’t grip and remove. This design makes them an excellent choice for security applications such as car license plates or gutters.
While it’s true that a specialized tool like a spanner or square driver is required to remove security screws, the great number of driver bits can definitely be a problem.
Frequently Asked Questions
There’s a lot of confusion and doubts surrounding these two terms, so we’ll try to clear them out.
Self-tapping screws can tap their own holes as they’re driven into the material. They can have a wide range of tip and thread patterns. When the tip is blunt, it means they must be used with a pilot hole. These screws are commonly used with metals, various types of plastics like plywood, fiberglass, or polycarbonates, and with cast or forged materials such as iron, aluminum, brass, or bronze.
Self-drilling screws, on the other hand, are actually a subtype of self-tapping screws. You can easily distinguish them by looking at their point, which is shaped like a twist drill and gently curved at the end. They don’t require a pilot hole as they can drill, tap, and fasten in one go. Being suited for more specialized applications, they’re typically used to fasten metal to metal and wood to metal. They work well with light gauge metals and other light, low-density materials.
Basically, self-tapping screws require a pilot hole, whereas self-drilling screws don’t.
Cam-out happens when your screwdriver or bit slips out of the screw head. This can lead to stripping a screw head, thus rendering the screw useless, splitting the wood you’re working on or damaging other materials, and even injure you.
Some screws are specifically designed to handle more torque and avoid cam-out. To reduce the risk of cam-out, you need to give your screwdriver or bit more points and grooves to hold onto. For this reason, screw heads such as the TORX and other star-shaped heads and selecting the right bit for them are crucial in avoiding cam-out.
Again, the best way to prevent this type of issue is by selecting the right bit for the screw head.
We recommend avoiding cheap bits because they’re more likely to waste most of your screws, making them even more expensive in the long run.
Other important points include using the right bit size and making sure not to angle your bit in a way that leads to an incorrect turning.
Once the screw heads are stripped out, you won’t be able to remove them with your regular tools. You also can’t, and shouldn’t, try to drive them further in.
To remove stripped screws, you can use a stripped screw extractor that you can easily find on Amazon for $14. However, if you’re not a contractor or someone who has to deal with screws on a daily basis, you can use locking pliers or vice grip pliers for screws that are still above the surface. For stripped screws that are deep into the surface, a common household rubber band can do the trick. By placing part of the rubber band over the head of the screw or in place of it, you can add the necessary traction for your screwdriver to finish the job.
There’s one right screw for every need and purpose, so it’s important to learn how to differentiate them and how best to use them.
Hopefully, this guide on the most common types of screws sheds some light on this, and you’ll be able to choose those that suit your project the best.