How to Correctly Use Sheet Metal Screws

drilled sheet metal screws
  • 2-4 hours
  • Intermediate
  • 5-500
What You'll Need
Protective eyewear
Power drill with appropriate drill bits
Sheet-metal screws
What You'll Need
Protective eyewear
Power drill with appropriate drill bits
Sheet-metal screws

Sheet metal screws were originally designed for metal, but they can also be used with plastics, rubber, or plywood.

Regardless of the material, the driving point needs to be larger than the depth of the material being driven into for the sheet metal screws to do their job correctly.

Without a long enough drive point, the threads will contact the materials before the hole is adequately bored, and the screw will snap. This renders them virtually useless, and you will have to restart the process of connecting the two pieces of metal with an appropriately sized sheet metal screw.

If you are planning to use sheet metal screws in your next project, the following will help you understand how to use them correctly, as well as answer some of the questions you may have about using them instead of another type of screw you may be more familiar with.

1. Select the Appropriate Sizing

Before you begin a project, you must choose the correct size screws. Choosing the correct sheet metal screws for the project is important, as the screw will be the main binder affixing materials together.

If your screws are the wrong size, your project may not hold together and will instead fall apart. Or, the project may simply be unsightly.

Screws are defined by a series of three numbers, and each is an important identifier when you are considering the effectiveness of the screw for a given project.

Size

The size of a screw is characterized by a proportional number from 0-24, which defines the head and shaft diameter, not the length. A size-8 screw is twice the shank diameter of a size-4 screw.

To obtain the actual diameter, multiply the screw size by 13 and then add .060 inches. Again, someone at a home improvement store can help you better understand the sizes and which one is the best for you to use for your project.

Thread Count

Screws also have a pitch that is equal to the number of threads possible within 1 inch of screw length. By multiplying the length (with respect to 1 inch) by the thread count, the number of threads for the screw can be derived, indicating the adhesion capacity.

Length

The last number indicates the physical length of the screw. At least half of the length of the screw must be embedded into the material being affixed together. This is an incredibly important point to keep in mind when deciding what screws to by for your project.

The numbers are always ordered by size, thread count, and then length. In this way, the standard screw is defined as 8-32 x 1 inch. In this example, a size-8 screw has 32 threads per inch and is 1 inch long. This is a fairly standard screw size but there are often other options as well.

2. Choose the Correct Material

Sheet metal screws come in a few materials to best suit the environment where the project will be housed. Before picking the correct material, you must understand the project you are taking on and where the final product will be located.

Standard screws are the most economical sheet metal screw option but can discolor with rust or corrosion when exposed to moisture, so they are not a great idea for a project that will live outdoors once completed.

Zinc-plated galvanized screws and stainless-steel sheet metal screws, on the other hand, are more expensive but stand up to the elements without deteriorating.

Because of the differences in prices and uses, it is important to by the screws that will work best with the specific project you are taking on.

3. Determine the Appropriate Head Style

Head style is another important factor to consider when deciding which type of screw is the best option for you. The head style of the screw allows for the materials being affixed to the screw to be protected.

Pan heads are raised above the surface. Oval heads are sometimes preferred because they provide a finished appearance. Flat-head screws are best when countersunk. Hex washers come with a neoprene washer designed for use with water.

With all screw heads, over-tightening or over-driving the screws can strip the heads or mar the materials, so be careful not to do so.

4. Know the Difference Between Pilot Holes and Self-Tapping Screws

Sheet metal screws can be either self-tapping or standard, and it is important to know which one is right for you.

Self-tapping screws come with a notched tip that acts as a drill bit to drive the screw and keep the thin metal in your project from denting. If these screws are being used, the screw can merely be fitted to the drill bit and driven in.

Standard screws, on the other hand, will need to have a pilot hole drilled in order to prevent splitting within the materials being fixed together.

Your pilot-hole drill-bit size will depend on the size of your sheet metal screw. A size-4 screw should have a pilot-hole drill size of 3/32 inches; size 6, 7/64 inches; size 8, 1/8 inches; size 10, 9/64 inches; size 12, 5/32 inches; size 14-1/4 inches, 3/16 inches; and 5/16 inches, 1/4 inches.

5. Drill Correctly

Always use protective eyewear to prevent metal shavings from penetrating the eye. Drill slowly and cautiously when driving sheet metal screws to prevent shavings and be sure the screw can adequately grab the materials. Before driving another screw, clear the drill bit of metal shavings.

What Makes Sheet Metal Screws Different from Other Screws?

If you are a do-it-yourself novice, you may be wondering how sheet metal screws differ from other types of screws. Sheet metal screws, as the name suggests, are designed specifically for use with sheet metal.

The screws have an exterior treading that covers their entire shank. This is not the case with all other types of screws. Conventional screws are only partially covered in threading.

Wood screws, meanwhile, have a wider spaced screw. Some of them also have a shank at the top, while sheet metal screws have a thread that covers their entire length.

The unique characteristics of sheet metal screws allow them to increase retention between the pieces of metal that you are fastening together. They also have a sharp tip which allows them to pierce objects easily.

Can I Use Sheet Metal Screws in Drywall?

If you have a drywall project and you have some sheet metal screws leftover from another project, you may be wondering if you can use the sheet metal screws in your drywall. The short answer is yes, you can use sheet metal screws in drywall.

The more complex answer is that while you can use sheet metal screws in drywall projects, drywall screws are definitely the preferred screw type for these projects.

While sheet metal screws have a rounded or flat top and a shank covering the entirety of the screw, drywall screws generally have a flat head.

Drywall screws are not a great option for sheet metal projects as they are generally not sharp enough to pierce through sheet metal, especially thicker pieces of sheet metal.

What Is the Advantage of Using Sheet Metal Screw Over Other Kinds of Fasteners?

The advantage of using sheet metal screws over other types of screws is that they are threaded in a way that allows them to increase the retention between the two pieces of sheet metal you are trying to bind together.

Sheet metal screws have sharper tips than some other types of screws. This is because sheet metal is more difficult to pierce than other types of surfaces, and one of the reasons why sheet metal screws are much more effective in projects involving sheet metal than other types of screws.

Sheet metal screws are often made of stainless steel, which is known for its durability. This means that sheet metal screws will last a longer time than other types of screws, making them a great option for a project you are hoping to get used out of for a long period of time.

Sheet metal screws are also advantageous over other screw types because they create very small holes, much smaller than some other types of screws. This means they are less visible than other screws. This also reduces the risk of the screw splitting or cracking a material, which larger holes can do.

Sheet metal screws are also known for being very strong and holding up well over a long period of time, making them a great option for projects that need to be capable of supporting heavy weights.

How Much Weight Can Sheet Metal Screws Hold?

As previously mentioned, sheet metal screws are a very durable type of screw. How much weight exactly the sheet metal screws can hold up, though, depends on a variety of factors, mainly what the screws are holding together.

Small sheet metal screws connecting thin, flimsy pieces of sheet metal and large sheet metal screws holding together larger, thick pieces of metal are going to be able to hold different amounts of weight.

Sometimes a single screw can hold as much as 100 pounds, but again this depends on what the screw is screwed into. Make sure to consider your weight requirements when planning out your project and what size of sheet metal screws to purchase for use in the project.

Can I Use a Sheet Metal Screw as a Ground?

While sheet metal screws may have some versatility and be a great option for sheet metal projects, sheet metal screws should not be used as a ground/to connect grounding or bonding connectors to metal enclosures.

Threads on sheet metal screws are too far apart to work well for ground projects which is why using them this way is not recommended.

Ground screws should be 32-thread pitch or finer. Ground screws should also be threaded into a metal box, something sheet metal screws do not do as well.

Ground screws also use friction between the surface and the screw and soil to transmit to the surrounding area, something that sheet metal screws do not do.

Sheet Metal Screws FAQ

How do you tighten sheet metal screws?

If you have loose metal screws, there are a couple of ways to tighten them.

Try wrapping fine wire, like steel wool, around the threads and then re-tighten the screws. You can also wrap tape around the threads or use liquid-based thread-stopping formula, which you can find at hardware stores.

How do you fasten sheet metal?

Sheet metal pieces are typically joined together with rivets, a method of bringing metal together using a cylinder-shaped post inserted into a drilled hole.

What are the best screws for sheet metal?

Self-tapping screws or self-drilling screws are often used with sheet metal. These screws require a pre-drilled hole.

How far apart should sheet metal screws be?

The number of screws you use to attach sheet metal depends on the job itself. To install metal roofing, for example, screws are placed every 12 to 18 inches apart.

For some projects, screws are placed 24 inches apart in sheet metal.

What are the two types of sheet metal screws?

Self-tapping and self-drilling screws are the most common screws used with sheet metal. Both types of screws are available at hardware stores.