Metal Roof is one of the most used roofing materials due to its durability and longevity. On sunny days, it can bounce back more sunlight to reduce heat absorption. And during the rainy and windy days, if fastened well, it can endure lesser damages.
It may seem that metal roofs are easy to install due to the process of laying down the metal sheets and fastening them to the support but it is really complex too. The most common problem of a metal roof is leaking through its screw holes because of its over-tightness in installation which would cause an overstress to the material and failure. If the installation is loose, the roofing material may tear or water may penetrate through the holes.
So the question is, should I pre-drill holes before installation?
The answer really depends on different contractors. The screws used for metal installation are self-drilling screws that don't require any pre-drilled holes as they can penetrate your material and support. But, there are several advantages and disadvantages of pre-drilling holes which may help you to decide.
1. Pre-drilled holes create a guide for your screws during installation. This will lessen the likelihood of installing the screws at an angle especially if you are using long-length screws. Screwing in an angle will create a portion of the hole that is not sealed and will contribute to your leak point.
2. Pre-drilling holes will create a cleaner and more aligned spacing. This allows you to run a chalk line and create perfect spacing intervals for your materials. It will also contribute to a faster installation because you can stack up metal sheets and drill them at once. You can save more time.
The only disadvantage of pre-drilling holes is once you drilled your material, there's no turning back. If you mistakenly drill a wrong hole for your screw, there is no way you can turn it back because it can contribute to being your leak point. Always run a chalk line first and be aware before drilling your material.
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When should I pre-drill holes?
Pre-drilling holes are most advisable when using a wood subsurface because it runs through your whole roof area which you don’t need to worry about too much unlike with purlins. Purlins are much more complex as you need to be mindful of the spacing to avoid drilling in the wrong spacing.
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Tips on fastening your metal roofs
1. Use the right screws and fasteners. Every material is designed for a specific purpose, from its corrosion resistance, length, drill point style, and different screw or fastener materials for a specific application like wood, brick, or metal.
2. Use a screw gun to fasten your metal roofing fasteners. Screw guns have the ability to have a specific torque to ensure that you don’t over-tighten the fasteners. There are actually different speeds for your drill, so you must match it with the type of support and screw type.
3. You can design your metal roofs with no exposed fasteners. This will ensure that there are no possible holes that the water can penetrate.
4. Use a chalk line to create straight and well-spaced intervals.