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Fasteners: An Important Element

Many decisions must be made for fastener selection

Dynamic Jun18 1

The fasteners used in any metal building or roofing project are such a small percentage of the contractor’s spending cost but they are also an important element to the project. If the wrong fasteners are purchased, they will not only cause problems for the installer but the end result of the project could be in jeopardy.

There are so many questions that must be considered before any purchase can be made. What is the material that I’m fastening? Am I working with dissimilar materials? Is the project in a highly corrosive environment where a long-life coated screw would need to be replaced by a stainless steel screw? Will the pullout and shear meet the engineering requirements for the project? Once I have the correct fasteners, do I have the proper tools to ensure the material will be fastened correctly?

Different Screws

Self-drilling screws for metal are designed to drill, tap and install in a one-step operation. With a drill tip on the end of each screw there is no need to pre-drill a hole as you would a tapping screw. The length of the drill bit on the fastener will determine the drilling capacity of the screw. A T-1 point is used for sheet-to-sheet stitching with a total steel thickness of 0.024-inch to 0.095-inch. A T-3, or purlin screw, is used for a total steel thickness of 0.036-inch to 0.210-inch. T-4s are used for a drilling capacity of 0.125-inch to 0.375-inch. T-5s have a drilling capacity of 0.250-inch to 0.500-inch. Self-tapping screws are available in Type A, B and AB. These screws were introduced years ago and are still available today. All three tapping screws require a pre-drilled hole, except when going into wood.

Self-tapping screws cost less versus self drillers but installing self-tapping screws will involve more labor. When using self-tappers, panel and structural thickness will determine the correct drill bit. Dynamic Fastener offers Dyna-Coat 1,000-hour salt spray premium coating for all of our fasteners.

When an application calls for stainless steel screws, the contractor has options. Bi-metal screws consist of a 300 series stainless steel head and body that is fused to a carbon steel body/drill tip. And, 410 stainless steel screws are available with the Dyna-Coat 1,000-hour salt spray premium coating. Zinc cast heads and stainless cap head screws that include a 300 series stainless cap mechanically formed around a high-strength carbon steel fastener are also available.

When a weathertight seal is required, metalbacked sealing washers are available. They may also be used to dampen vibration or simply act to provide bearing area. The metal is available in galvanized steel, stainless steel and aluminum. The inner diameters range from one to fit on a #6 diameter screw, to one to fit on a 1-inch bolt. The outer diameters range from 3/8-inch to 1 1/2 inches.

Fastening Metal

Screwguns are available corded and also battery operated to handle just about any metal that needs to be fastened. It is critical that a Versa-Clutch torque adjustment system is used to allow you to dial the proper torque needed to efficiently drive fasteners without stripping or breaking the fastener. When installing the T-1 and T-3 self-drilling screws, a 2,500-rpm screwgun should be used. A low 1,000- rpm/high-torque tool is ideal for fastening T-5s into 1/4-inch and thicker steel.

When fastening metal to metal in a light-duty application such as securing door trim, rivets offer a clean appearance. Using a standard rivet gun allows for quick and easy installation. Rivets are available in different diameters with multiple grip ranges. For instance, a 4-3 rivet identity would be 1/8-inch diameter (the 4) with a 0.126 to 0.187 grip range (the 3). The rivets are available in steel, aluminum, stainless steel and copper. When installing copper rivets you want to be sure you use the copper rivet with a brass mandrel. The last thing your customer wants to see is that rust streak on his brand new copper panel if you used a copper rivet with a copper-plated steel mandrel.

For aesthetic purposes, buttonhead, large flange, and countersunk head styles are available. Dynamic Fastener is now stocking 75 million rivets comprised of hundreds of different colors and hundreds of different rivets to match any panel and as an added bonus, all stainless rivets have grooved mandrels that will allow the rivet jaws to bite, making the pulling of the very hard stainless rivets an easier job.

Ken Webb is a sales manager for Dynamic Fastener, Kansas City, Mo., and has been with the company for 30 years. To learn more, visit