The humble metal roofing screw is the unsung hero of the roofing industry. While the metal panels may get all the glory, it's the strength of screws and fasteners that hold those panels in place and keep your roof watertight.
In this article, we'll take a look at the different types of screws and fasteners used in metal roofing, and explain when and how to use them. We'll also discuss the different materials and coatings available for metal screws, so you can choose the right ones for your specific installation. So without further ado, let's take a closer look at the anatomy of a metal roofing screw!
Types of Screw Drill Point Styles
The first thing to understand about the anatomy of a metal roofing screw is the type of drill point used. There are three main types of drill points: self-drilling, self-tapping, and self-piercing.
Self-drilling screws are the most versatile option as they don’t require the use of a pre-drilled hole. These are the most common type of metal roofing screws and the ones you’ll likely use the most often.
Self-tapping screws have a pointed drill bit that requires the use of a small pilot hole in the panel before the screw can be installed. Self-tapping screws are the preferred choice when a panel needs to be installed over an existing roof.
Finally, self-piercing screws have the sharpest points that allow the metal screw to penetrate the panel without the need for pre-drilled holes. These are best used in applications where the material is thick and requires extra strength.
Screw Head Types & Styles
The next aspect of the anatomy of metal roofing screws is the type and style of the head. Screw heads come in a variety of shapes and sizes, but the most common are the hex head, the flat head, the truss head, and the pan head.
Hex-head screws have the classic six-sided shape and are the most common type of metal roofing screw. They’re the strongest type, with the widest range of sizes available.
Truss-head screws are similar to the flat head but have a wider surface area which makes them better suited for larger panels or thicker materials.
Finally, the pan-head screw has a rounded top that is the least visible once installed. These are the most popular choice when installing metal siding or flashing.
Screw Head Materials and Coatings
The metal roofing screws and fasteners available come in a variety of materials, the most common being steel, stainless steel, and aluminum. Steel is the strongest option but the least corrosion-resistant. Stainless steel screws provide the best corrosion resistance but are the most expensive metal. Aluminum is the least expensive option but also the weakest.
Coatings are also available to improve the absolute corrosion resistance of the metal roofing screws and fasteners. The most common coatings are the galvanized type, which is the cheapest and the easiest to find, followed by the zinc-coated and PVC-coated types. Each coating offers a different level of resistance to corrosion, so be sure to choose the right one for the application.
Selecting the Right Length & Diameter
Finally, the last step in the anatomy of metal roofing screws is selecting the correct length and diameter for your project. The correct length screw should penetrate the material being fastened by at least 3/4 of an inch, but not more than 1 inch. This ensures the screw will be securely fastened without the risk of it pulling out.
The diameter of the metal roofing screws and fasteners is also important, as a larger diameter correlates with the strength of the screw. The most typical screw sizes used for metal roofing are the 8-gauge and the 10-gauge, but the thickness of the material being fastened should be taken into consideration as well.
More on selecting high-quality fasteners
Metal roofing screws and fasteners are a crucial part of any metal roof installation and the right type and size should always be used to ensure the best performance. By understanding the anatomy of the different types available, you can make the best choice for the metal surface of your project. With the right screws and fasteners in your toolbox, you can be sure to have a secure and long-lasting roof!
Ready to start attaching those metal roofing panels? Check out our blog How to Attach Metal Roof Panels: The Step-by-Step Guide.