Photo: Perry Mastrovito / Image Source / Getty Images
Difficulty
Simple
Flex your DIY muscles.
Time to complete
1 hour, 30 minutes
Between one and two hours, depending on the number of sheets.
Cost
$1,000+
This one takes some heavy-duty equipment.
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What you'll need:
TOOLS
Safety goggles
Thick work gloves
Long-sleeved shirt
Long pants
Boots
Tin snips or power shears
Tape measure
Flat, stable workbench or other surface
Adjustable clamps
Permanent marker
Combination square
Electric drill with metal-cutting drill bit
Electric drill nibbler tool or attachment (optional)
SUPPLIES
Metal roofing sheets
Metal makes for a stylish, durable roofing material that protects your home with a unique look. If you’re installing a roof yourself, you should know how to cut metal roofing sheets to the correct size. The project is relatively easy, but the cuts must be precise and well-planned to fit your roof and prevent leaks and other issues. This step-by-step guide lays out what you need to do to cut metal roofing.
Choosing the Right Tools to Cut Metal Roofing
Photo: THANAGON / Adobe Stock
You should use certain tools to cut metal roofing to ensure it’s done safely and properly.
Tin Snips
Tin snips are essentially scissors for cutting metal. They’re ideal for short, precise cuts or cutting individual sheets by hand. You may wish to use multiple types of snips for this project:
Yellow or plain-tip snips cut straight lines.
Left-handed snips cut counterclockwise so you can make rounded cuts to your left.
Right-handed snips cut clockwise so you can make rounded cuts to your right.
Power Shears
These electric or pneumatic tools make straight cuts more quickly than tin snips. You may wish to invest in power shears or borrow some from a friend if you have a lot of metal sheets to cut. Tin snips are relatively inefficient for large projects and will take longer to get the job done.
Buying Metal Roofing Panels
To determine how many metal panels you need to purchase to cover your roof, use a tape measure to determine the length and width of each section of your roof. Divide your roof’s total area by the size of the roofing sheets you plan to use to figure out how many panels you need.
Stay Safe With Personal Protective Equipment
Photo: Евгения Трастандецка / Adobe Stock
Cutting metal is a risky task that can create dangerous metal dust and fragments. To stay safe, wear long sleeves and pants, thick work gloves, hard boots, and proper protection for your face and eyes. Also, it’s good to minimize distractions while you work.
Lay Out Your Metal Sheets
You’ll need a flat, stable surface to work on, such as a sturdy workbench. Lay the metal roofing sheets out on the surface with the underside of each sheet facing up, then pin them in place with adjustable clamps. The panel undersides are flatter than the top edges, which have ridges that stick up. Laying the sheets upside down will make straight cuts much easier.
If you are installing a corrugated metal roof, it's important to overlap the sheets with at least two ribs—not just one—to prevent water from getting into the seams. For screw-down metal roofs, you should use seam tape.
Measure and Mark Where Cuts Are Needed
Use the roofing calculations you took before purchasing your metal panels to determine how big each panel needs to be. Measure along the sides of your panel with your tape measure and use a permanent marker to mark where you’ll cut.
Hold your combination square flush against the edge of the sheet and line it up with each mark. Use your marker to draw a straight guideline across the entire sheet at each mark. You’ll follow these lines when making your cuts. Each mark and line you draw needs to be placed precisely to avoid gaps, leaks, and rust in your roofing, so double check every measurement you make.
Make Your Straight Cuts
Slowly and carefully cut along the straight guidelines you’ve marked. If using tin snips, use them as you would a pair of scissors, lining them up with a guideline and cutting slowly. With your opposite hand, hold the sheet and lift it away from the shears as you cut. Expect cutting to become more difficult around the raised ridges of each metal sheet.
If using power shears, line them up with a guideline, press the trigger, and hold them steady as they move across the metal sheet.
Make Round or Other Specialty Cuts
Photo: vladdeep / Adobe Stock
You may need to create an opening in the middle of one of your metal pieces, such as for a vent pipe. Measure where the hole needs to go and trace the object with your permanent marker. Then punch a pilot hole using an electric drill fit with a half-inch metal-cutting drill bit.
With your pilot hole cut, you can fit a pair of tip snips into it and slowly cut along the guideline. Alternatively, you can use an electric drill nibbler tool or attachment. Like a saw or power shears, start at your pilot hole and push the nibbler forward to follow the guideline.
Cutting Metal Roofing as a DIY vs. Hiring a Pro
According to HomeAdvisor, metal roofing material costs between $120 and $900 per square. That means that to cover the average 1,700-square-foot roof, you’ll spend $2,040 to $15,300 on materials alone. The cost to install a metal roof using professional labor ranges from $5,700 to $16,140 on average, so you can potentially save more than $3,000 with a DIY project.
However, it’s worth noting that while cutting metal roofing yourself is a simple task, successfully installing that roofing is a serious job that can be dangerous for you and for your home if done improperly. For most homeowners, the best approach is to hire a local metal roofer, especially for a whole roof replacement. Standing seam metal roofs require special tools and unless you know what you are doing, one simple error can lead to a major leak. Unlike shingles, metal roof repairs are extremely expensive and many professionals may not even repair a metal roof that they did not install.
Frequently Asked Questions
While a high-speed circular saw will cut through metal and can even cut through multiple sheets at once, the fast-spinning saw blades create a lot of heat. This heat can damage paint and other protective coatings, leading to serious problems like rust over time. The cost to paint a metal roof again to avoid this damage is typically an additional $0.50 to $1 per square foot.
It is not always necessary to put wood stripping under a metal roof, but some metal roofs require stripping to work efficiently. A lack of wood stripping can cause condensation issues under certain roofs, so use the roofing manufacturer’s specifications as your guide.
There are advantages and disadvantages to metal roofs in cold climates. Metal roofing stands up extremely well to harsh winters as long as it is properly insulated. Snow and ice slides right off a residential metal roof, preventing the formation of ice dams. Because of this, they require snow guards, which prevent the ice and snow that slide off your roof from causing a sort of "mini avalanche" that can damage property and put people below at risk.
The average roof requires about 17 metal sheets. Each roofing sheet takes about five minutes to measure and cut.
