Which Screws to Use

different kinds of screws on a table
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Whether you're building a privacy fence or attaching floating shelves to the wall, it's important to know which screws to use for your home DIY projects. When in doubt, you can always ask an associate at your local hardware store about the specifics of your project and the screws and tools you'll need to complete your problem.

That being said, it is helpful to know a few basics about which screws to use for your home projects so you can master your DIYs and become a home reno pro.

Screw Length

Perhaps the most important part of picking screws is picking screws the right length. If your screw is too long, you risk damaging the project and a screw that is too short won't hold.

While there isn't just one size of screw that will work for any given project, we recommend always finding a screw that is at least half of the thickness of the bottom material that you'll be working with.

When you drill a pilot hole, you want to drill it deep enough that your screw will attach the two materials together and end up one-third to halfway through the second material. It's a really general formula, but it definitely helps.

Screws are measured in threaded length, so make sure you take that into account if you're trying to use old screws that you're unsure of the length on.

screws in tool box compartments

Matching Screws

If you are trying to match old screws in a project, your best bet is to take one of the old screws to the hardware store and match the screw that way.

If you don't have that option, do your best to take note of the shape, material, length, and girth of your current screws. Also, make sure you know the head shape. An associate should be able to help you narrow down exactly what screw you need or at least send you home with an option or two that will get the job done.

Popular Screws: Flathead Screw

Often, flat head screws are used in machinery projects as well as projects around the home where metal and wood need to be joined. Flathead screws can be attached using a flathead screwdriver or using a flathead drill bit.

Wood Screw

Wood screws are pretty self-explanatory. Wood screws are used for wood projects that involve securing or joining two pieces of wood together. Wood screws are typically shorter than metal screws but can sometimes come in longer lengths.

Wood screws, as opposed to other types of screws, come with a much sharper head so that they can easily bore through the wood. Though it's usually still a good idea to drill a pilot hole when possible, the tip of a wood screw is strategically pointed so that getting through the wood is easier.

You can purchase wood screws at any hardware store and can buy them with a variety of head options.

wood screw

Metal Screws

Metal screws are used for metal projects and are also available in a variety of lengths with different head options. Metal screws are used to connect metal to metal or another type of material.

As a general rule, sheet metal screws have a tighter tread than wood screws do, and the threaded area of the screw covers more of the screw. This is so that your metal materials can be securely fastened together with no slipping and sliding.

A lot of the time, metal materials come pre-drilled, but if you do have to drill your own holes in the metal, use eye protection to keep your eyes from being the accidental recipients of metal scrap.

Security Screw

If you want the job to stay done, use a security screw. Security screws have a special head that prevents tampering. Once a security screw is on, it does require a special tool to remove—and even with the tool, it's not easy.

When you're building something that needs to stay put, and you want to make sure no one tampers with it, use a security screw.

Machine Screw

Machine screws are also pretty self-explanatory. Machine screws are larger than other types of screws because they are most commonly used in projects where machines need to adhere together.

These screws aren't as commonly used as the basic metal and wood screws but are definitely handy to have around if you're working on more advanced DIY projects.