As the name suggests, metal roofing screws are primarily used to attach roofing panels. Roof builders and project engineers have understood the importance of using specific screws for specific purposes. This has led nut bolt manufacturers and roofing screws manufacturers to start making screws that are built for specific purposes. Gone are the days when one size fits all approach was prevalent, nowadays longevity of materials used – has become the primary goal for any construction project.
Generally, the cost of the screws is less than two percent of the entire cost of building, or less than one and a half percent of the total cost of the project. Despite their nominal cost, screws define the success or failure of a project. They are a quintessential part in any construction project, and disregarding their importance can lead to substantial costs down the road.
How to choose Metal Roofing Screws?
Metal roofing screws are available in a number of specifications. From different sizes, designs, and materials, there are a plethora of screws out there which are specifically designed to cater to different scenarios.
Roofing screws are categorized according to their thread diameter, threads per inch, length, head style and type of drill point.
Following pointers will help you find the fasteners you need:
- The selection of correct fasteners depends on the length of the screws, drill tip of the screws and the purpose – roofing or cladding.
- The application of screws decides what type of screw you will choose. You need to select the coating based on the environment and corrosion resistance required. You need to choose the drill tip of the screw and select the EPDM Washers – Metal Bonded or Low carbon EPDM Ring Washers.
- The mechanical properties of the screws also are a factor for deciding the type of screw to be used. These properties include the structural strength of the screw, pull-out strength, ductility and the screw’s compatibility with the sheeting and structure.
Why does size matter?
Screw size refers to a lot of things. It refers to the size of the length of the body of the screw, it refers to the diameter of the screw and the size of its head. Screws are measured from the base of the head to the end tip of the screws. Choosing the proper length is critical with respect to the types of insulation and increased breadth.
A screw’s diameter is also referred to as its gauge. The most commonly available gauges are available in diameters between the ranges of two to sixteen. For general purposes, an eight-gauge screw is the best bet. However, heavy materials may require a gauge size of around 12 to 14. Lighter materials, like wood, may require a six-gauge screw. Following points will help you get the right sized screw:
- The choice of diameter of the screw will depend on the width of the material which you are screwing into, and the weight that the screw will structurally support. Stouter screws can carry more weight on them, but have to be anchored in more material.
- Also, a screw less than half the length of the substrate will not anchor properly, and a screw longer than half the length of the substrate will risk damaging its opposite side.
How crucial is choice of material?
Selection of fastener material should be based on the intended use of the fastener, along with the expected long-term requirements of the project. How the fasteners will react to the environment, what kinds of materials are being attached, also hold weight over the decision of choosing the right material for the fastener.
Choice of the right screw material ultimately depends on whether it will be used outdoors or indoors. You can choose to go with expensive zinc screws, or opt for aesthetic materials/coatings for visual appeal, but when it comes to outdoor use, screws need a lot more protection against corrosion from moisture and temperature change when compared to screws that will be used indoors. The best outdoor fastening solutions are silicon-coated bronze or stainless steel.
Due to the lack of chromium in their composition, most of the steel screws get rusted faster as compared to stainless steel screws which have a sufficient amount of chromium in their composition.
Even stainless steel screws will corrode under certain conditions. However, galvanized screws can withstand the harshness of the external factors the best, but do plan on replacing them at a later date with a larger screw once the zinc coating has been depleted. For places where corrosion resistance is needed, the best options would be stainless steel and bi-metallic fasteners.
Screw caps also help to make sure that the exposed parts of the screw are protected against the external elements like water and wind. You also need to keep in mind to use the same material for your screw as your roofing panels to avoid galvanic corrosion.
Galvanic corrosion is a phenomenon which occurs when two different metals corrode after being charged through electrical contact. To avoid this, we can use nylon-washers which are effective in ensuring that stainless steel fasteners do not come in contact with the other metal panels.
Choose Metal Roofing Screws according to application
You will probably notice that irrespective of their small stature, using the right kind of mechanical fastener plays a key role in the long-term performance of a project. Therefore, it is very important to ensure that you are using a fastener that caters to specific needs. Failing to do this can result in failure of both the fastener and the panel system.
Apart from material and size, following are some things that should be taken into account as per the structural aspects when selecting a fastener. They are as follows:
- Analysing the gauge, or thickness of the panels through which the fastener will be installed can help you to narrow down the available options of screw diameters and point configurations.
- Being aware of the spacing of the fasteners and the roof panels, and the spacing between the panels themselves. Taking note of pull-out and pull-over force is equally important.
- Precisely calculating the diameter of the fastener head or the diameter of the sealing washer, responsible for resisting the pull-over forces on the wall panel. Furthermore, you should know about the configuration of the wall panels and the metal panels gauge to ensure proper installation.
Conclusion
Choosing metal roofing screws is an easy task if you take a few vital points into consideration. These include the intended application of the screw, the substrate it is being used to adjoin, and its long term feasibility. Get in touch with ScrewExpert to fulfil all your project requirements, and to get some of the best fastening solutions available in the market today. As a leading nut bolt and roofing screws manufacturer, ScrewExpert has bountiful experience in the world of construction and aims to constantly provide the best possible solution to your specific needs.