Metal roofing can be an excellent roofing choice because they’re durable, lightweight, sustainable, and energy-efficient. However, not all the sheets will match your roof perfectly, especially if you have vent pipes or a chimney.
To cut metal roofing, you’ll need to prepare the cuts and take many detailed measurements to finally slice that panel.
It might look daunting, and the truth is that this project has a high risk of injury. However, there are certain tools that can make this an easier task. Whether you choose tin snips, nibblers, or a circular saw will depend on the type of cut you’re going to make and how experienced you are when it comes to roofing.
Read on to find out the step-by-step guide on how to cut metal roofing.
Tools and Supplies You’re Going to Need
Before you begin, you need to gather all of your supplies for cutting your metal roofing.
- A wide, stable workspace
- PPE (Personal Protective Equipment): safety glasses, dust mask, work gloves, earplugs
- Combination square
- Measuring tape
- Permanent marker
- Metal roofing sheets
- Cutting tools (tin snips, electric shears, a nibbler, or circular saw)
No matter the tool you choose for the job, cutting metal can always be dangerous because there’s a risk of producing metal dust and fragments. Wear leather gloves, safety goggles, and cover up with a good pair of boots, long sleeves, and long pants for additional protection.
If you’re working with nibblers or a circular saw, you’ll also need a dust mask and earplugs.
How to Cut Roofing Sheets Step-by-Step
The preparation of the metal roofing panels is the same no matter which tool you’re going to use for cutting them. While it might seem unnecessary, preparing the cuts is a way of ensuring that you make exactly the cuts you need without wasting time because you get them right the first time. To do this, you have to:
- Place the roofing sheet on your workspace with the underside up. This way, the ridges won’t stick up and will be easier to cut.
- Secure the sheet with adjustable clamps so it doesn’t move during the cutting process.
- Calculate the number of panels you need for the roof. In this step, you have to figure out how big the panels need to be and how many you’re going to need by measuring each section of your roof. Divide the estimated area of your roof by the size of the sheets, or simply use a metal roofing calculator like this one.
- Measure roof vents, chimneys, and any other areas that will require cuts and use a tape measure and permanent marker to draw a line on the metal panel to cut over. For straight cutting lines, you might want to use a combination square.
- Measure twice to be as precise as possible. You don’t want any gaps between your panels that can compromise their integrity and that of your house.
Now is time to put your PPE on and select the tool you’re going to use to cut those metal roofing sheets.
Using Tin Snips
Tin snips are basically scissors for metal. They’re available in different sizes and calibers and can be used to cut tin, steel, aluminum, vinyl siding, and wire mesh too. They can be easily recognized by the color of their handles.
- Center or straight cut tin snips: are the ones you’re most likely going to need when working with metal roofing. They have yellow handles and make straight cuts, and cut openings in the middle of a panel. However, they’re unsuited for sharp curves.
- Right-hand tin snips: have green handles and are used to remove metal on the right side of the cut line and to cut clockwise curves.
- Left-hand tin snips: have red handles and are used to remove metal on the left side of the cut line and to cut counterclockwise curves.
Tin snips aren’t suited for thicker gauge styles of metal roofing, and they can’t cut along corrugations, only across them.
To cut metal roofing with tin snips, you have to use the tool as you would a pair of scissors: just make short, quick cuts along the marked line. Keep the blades level with the material at all times.
The process can be a bit slow, require some effort, and are not very accurate if you’re working on large panels, which is why tin snips are recommended for small jobs that only require a few shortcuts. Using them to make longer cuts can lead to warping the metal.
A nibbler is a tool designed for cutting sheet metal with no distortion and the most efficient and effective way to cut curves and other specialty cuts on metal roofing panels, especially corrugated or curved ones. You can find nibblers as attachments for an electric drill or as a separate power tool.
These tools work by making quick punches in the material, allowing you to make cleaner and more accurate cuts. They’re easy to maneuver for curved cuts and around corners without jamming, which makes them perfect for tasks like cutting a hole for a vent pipe.
On the downside, nibblers are rather expensive, and they’re only suitable for specialty cuts, so they’re not a good option for straight cuts.
To cut metal roofing using nibblers, you have to push it forward along the marked line you drew, starting at the edge of the roofing panel. Make sure to keep the tool parallel to the material, so it doesn’t bend.
Using a Circular Saw
A circular saw can be an excellent choice when you need to cut through multiple roofing sheets. However, if you’re inexperienced in metal roofing or in operating a circular saw, you should avoid this method because it can be quite dangerous. Moreover, they’re very loud and can create dust and metal fragments that are incredibly dangerous if you’re not wearing your PPE.
Only specialty blades designed for roofing can be used, and they can be costly to replace if you’re cutting a lot of metal. Other types of blades can produce enough heat to damage the protective coating of the roofing if you’re not careful.
To cut metal roofing using a circular saw, you have to:
- Position the exposed side of the panel down to avoid damaging the finish.
- Attach the blade and lower it onto the cutting edge you’ve marked.
- Move the saw slowly using light pressure. Let the tool do the job and don’t force it through the metal.
- Wipe the panels immediately after cutting to remove any metal residue.
Using an Angle Grinder
While it can technically get the job done, we don’t recommend using an angle grinder to cut metal roofing.
This power tool can cut through metal if it’s equipped with the right cut-off disc, but it’s too abrasive for thin metal roofing. The grinder generates a lot of heat that can melt some protective coatings of the material, while the sparks it produces can cause great damage to them. This will reduce the longevity of the sheet and might expose your house to structural damage over time.
Moreover, the grinder can leave extremely sharp edges after cutting, which can be incredibly dangerous for beginners and pros alike.
Metal roofing is thin enough to be easily cut with safer tools. The risk of injury and damage to your roofing panels is high when using an angle grinder, you should go for another tool for this project.
It’s crucial to clean the metal roofing panels after cutting them because the process generates large amounts of dust that can rust and affect the integrity of your roof if left to accumulate.
Smooth the Edges
You can start with 220-grit sandpaper to smooth the edges of the metal roofing panel after cutting. Then, switch to a finer grit for the final touches. Using a polishing pad to remove any remaining dust and buff out the shine can also be a good idea.
The roof is an integral part of your home, so you need to make sure everything is perfect when installing metal roofing. When cutting the panels to fit on your roof, it’s crucial to ensure accuracy and not to damage the protective coating of the panels to protect their integrity.
When it comes to the right tool for the job, there are three options you can choose from, depending on the type of cut you need to make and how experienced you are.
Whichever you use, remember to follow the instructions carefully and always wear your safety gear!