SFS Group, USA
In the majority of roofing and cladding applications, metal panels are installed onto substructures. Although seemingly trivial, the selection of the correct tools and the application of proper installation procedures is paramount for the completion of a successful job. This article will outline the necessary tools and techniques required to ensure installers successfully complete projects without damaging fasteners or application substrates.
Select the Correct Drive Bits and Metal Panel Installation Procedure
Selecting an incorrect drive bit can result in serious efficiency and performance issues. A recessed magnet should be used for external drive fasteners and the correct size and design drive bit is always used for internal drive fasteners.
It is equally important to properly tighten fasteners into the application substrate. The majority of roofing and cladding fasteners will feature some type of bonding washer to provide a water-tight seal. Care must be taken to correctly drive the fastener into metal panels. Use the image below as a guide.
Metal panel installers should also take care to select a drill gun set to the correct rotational speed (RPMs). The following tables can be used as general guides for selecting the correct installation speed. However, it is a good idea to check with the fastener manufacturer for exact specifications.
Although similar in appearance, drill guns and impact drivers have differences that will affect the performance of fasteners. During metal panel installation, drill guns provide a constant rotational torque. In contrast, impact drivers produce more torque applied in short bursts. This results in “impacts” which drive screws more effectively. In addition, impact drivers are typically more compact
and tend to slip less frequently.
On the surface, impact drivers appear to be an obvious improvement over drill guns. However, the increased torque and “impact” action may result in damage to the fastener, the sealing washer and the installation substrate. Fasteners can be damaged in three different ways by impact drivers. First, for painted fasteners, chipping and damage can occur. This will result in both an unfavorable appearance and increased corrosion risk.
Second, depending on the material composition of the fastener, the internal or external drives can be damaged. For soft stainless alloys and zinc/ aluminum alloys, the use of an impact driver can permanently deform internal drives and “grind-down” external drives. In some cases, the drive will wear down prior to full installation. In addition, repair teams will have difficulty uninstalling the part if roof replacements are required.
Finally, the rotating and cutting action caused by drill points can cause fasteners to “burn up.” At increased torques, installers risk generating excessive heat that damages the fastener points. This will result in the inability to install the fastener and can cause damage to the substrate. Slower RPM screw guns tend to avoid these potential issues.
The increased rotational speed and torque of impact guns can result in overdriving. In addition to damage caused to the head of
the fastener, there is an increased risk of water damage. If a fastener is overdriven into the metal panel, the assembled washer may not properly seal or may be irreversibly damaged. This may result in future leaks and water damage.
The application substrate can also be seriously damaged by using the incorrect tool for fastener installation. For instance, increased rotational speed (RPMs) can result in the formation of burrs on metal panels. These burrs can compromise sealing washers and increase corrosion risk.
In wood and composite applications, RPMs above 2,500 can result in damage to the attachment substrate. This results in compromised holding strength and can sometimes lead to application failure below provided design values.
Should I use a regular drill gun or an impact gun to install metal roofing panels? Installers should always use regular drill guns to install metal roofing and cladding panels. Impact guns apply increased rotational torque, which can damage the parts and make installation impossible.
Does it matter what speed I set my drill gun to when installing metal roofing panels? Yes, the rotational speed or RPM should be set in accordance with the roofing application. Wood substrates and metal substrates should be installed at different speeds. Refer to the tables on page 20 to determine the correct drill speed for your application.
Do metal shavings, burrs or pigtails cause damage to the roof? Metal shavings and pigtails cause damage to exposed
fastener roof systems. It is important to avoid the “canning” or burring that occurs when installing fasteners into metal roofing applications. They can contribute to corrosion, cause leaks and potentially lead to serious damage. Always ensure the proper drill
gun is used and set to the correct rotational speed.
How do I avoid damaging rubber washers in metal roofing applications? When installing fasteners with attached rubber washers it is important to avoid squash out failures. This occurs when the fastener is over-driven into the application substrate. To avoid this type of damage, always use a standard drill gun set to the correct RPM.
Contractors should always ensure their teams are fully aware of proper installation procedures and tools for metal panel applications. Refer back to this guide anytime for guidance in future projects or contact SFS for additional tips and strategies.
Oriented strand board consists of wood flakes and strands pressed into large boards using water-resistant adhesive. The result is an affordable engineered wood stronger than plywood and practical for a variety of interior sheathing projects including roofs, floors and walls.
While it’s hard to find fault with OSB, there are special considerations for which builders should account. Mainly, when compared to other engineered woods, it presents an increased likelihood of splitting or for causing stripped fasteners. Therefore, it’s best to use screws specifically designed for OSB to significantly lessen such risks.
The best way to minimize the potential for stripped fasteners is by using screws with aggressive threading. This references a higher thread pitch (the distance between two threads). The lower the threads-per-inch (TPI), the deeper the ridges and greater
the fastener grip. The aggressive threading ultimately leads the screws to provide greater pull out resistance strength when connecting OSB sheathing.
■ Sharp point for self-drilling. A sharp point enables smoother piercing of the wood and less physical pressure needed when applying the fastener.
■ The type of fastener head. There is no one style of screw head that is objectively best for OSB construction. While a tall hex washer head provides added stability during the application, countersunk alternatives lay flush with the OSB, making it ideal for subfloor applications.
■ Rust resistance. Warping due to moisture exposure is considered the Achilles’ heel of OSB, so it’s rare for builders to use it for exterior applications. However, there are lesser-known OSB board options with high water resistance, leading to some contractors bucking tradition and featuring OSB in ways that expose it to weather. In such cases, you will want fasteners that offer inherent rust resistance.
Can I Use Other Wood Screws with OSB?
The short answer to this question is that, yes, you can fasten OSB with other types of wood screws. However, you increase the chances of splitting wood and stripping screws, leading to compromised fastening
Do OSB Screws Work for Other Types of Wood?
Screws intended for OSB satisfy the similar needs of other softwoods, like plywood and pine. However, they’re not the best choice for hardwoods which may be best served by fasteners with less aggressive threading.
How Do Screws Compare to Nails for OSB?
Typically, screws are best for OSB and softwoods due to the heightened chance of splitting when nails are used and easier removal at a future date. Nails result in a weaker connection and can damage the integrity of the subfloor or sheathing. Also, OSB subfloors applied with nails rather than screws are more likely to creak.
Have more questions about OSB screws? We can help. You don’t have to select OSB screws alone. The SFS team is ready to answer any additional questions and suggest which is best based on your individual needs. Call 610-376-5751 to learn more
about fasteners, manufacturing practices and supplementary services. Please visit www.sfs.com for more information. Reprinted with permission from SFS Group, USA.
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