How to Cut Aluminum Siding

Installing your own aluminum siding is a great way to save money while improving the curb appeal of your home. Aluminum siding comes in pre-measured lengths. To install it, you will need to trim and shape the siding to the contours of your home. Follow this guide to cut aluminum siding without damaging it or your saw. 

How to Cut Aluminum Siding

There are three kinds of cuts you’ll need to make in order to install the aluminum siding.

1. Vertical cuts are the most common. These trim the aluminum siding to the appropriate length for installation on your home’s exterior.
2. Horizontal cuts are less common, but still important. Sometimes there isn’t room for an entire piece of siding, such as at the top of a wall. Cutting the siding horizontally creates a shorter piece of siding that can fill the gap. 
3. Cut-outs are necessary when you encounter architectural or structural irregularities. For instance, you may need to shape an opening in aluminum siding where a pipe or vent exits the home. 

Each kind of cut requires a different process and specific tools. Learn how to execute each kind of cut in the sections that follow. 

How to Make Vertical Cuts in Aluminum Siding?

You’ll be making many vertical cuts as you trim the length of the siding to suit the needs of your installation. It’s usually easiest to make these cuts close to your installation site. Pay attention to the temperature and humidity outside to stay safe while installing exterior building projects.

1. Set up your workspace. Safe and accurate cuts require a stable, level cutting surface. Two sawhorses and a sheet of plywood make a great work table. 
2. Measure twice. Once you cut the siding, you can’t join it back together. To make the most out of your materials, double check every measurement before making a cut. Use a tape measure and a shop pencil to mark the location of the cut. Place an X on the waste side of the line. 
3. Protect your eyes. When cutting aluminum siding, there is a chance that slivers or shards may become projectiles. Wear goggles to protect your eyes during every single cut. 
4. Cut once. A chop saw is the easiest choice for making vertical cuts in aluminum siding. You can also use a miter saw or radial-arm saw. Cut along your pencil mark. Place the waste off to the side – you may find these shorter pieces useful when fitting siding around tricky areas. 

Can you use a scroll saw to cut aluminum? I answered that question.

How to Make Horizontal Cuts in Aluminum Siding?

Horizontal cuts are also known as rip cuts. Luckily, aluminum doesn’t have the knots and imperfections that make ripping wood such a tricky proposition, so this is a pretty easy project. 

1. Measure carefully. To cut a piece of aluminum siding horizontally, you will need to make a straight, even line. Use a measuring tape to mark your desired cut at regular intervals. Then, connect the marks using a straightedge. 

Check your measurements by measuring from the top and bottom of the siding in several places. The distances between the siding edge and the cut line should be consistent throughout. 

2. Use the right tool. A table saw is the best choice for making horizontal cuts in aluminum siding. Circular saws can also work, but there is a risk that the pulling motion of the saw may cause the aluminum to snag or jerk, risking serious injury. 

Mitigate the risk of using a circular saw by installing the right kind of blade. Use a non-abrasive carbide blade rated for aluminum. It should have a low tooth count to reduce clogging.

3. Plan for lubrication. Cutting aluminum is tough on saw blades. Before cutting, apply saw blade wax to the blade’s surface. Check the lubrication of the blade throughout the cutting process. Not only is it safer, it will extend the life of your blade. 
4. Support the siding. If you’re using a circular saw, make sure the siding is securely clamped. This makes it easier to cut along your intended line. Also, if the circular saw’s blade catches or stalls, clamped siding is less likely to go flying and cause injury. 

Whenusing a table saw to make long horizontal cuts, have a plan to support the siding as it comes off the table. This could mean extending your work table so the siding can ride on top of it after being cut. Or, you could have a companion help support the siding. 

5. Make the cut. Always move slowly and carefully when using a power saw. Remove loose clothing or dangling jewelry. Ensure the area is clear of cords or other trip hazards. When you complete the cut, turn off the power to the saw, and wait for the blade to stop spinning before setting it down or retrieving your cut siding. 

Tools for Making Specialty Cuts in Aluminum Siding

Installing aluminum siding requires you to work around the features of your home. Decking, porch roofs, dormers, and exterior pipes are all examples of obstacles that siding needs to fit around. 

There are a few tools that can help you get the job done. 

Tin Snips

Tin snips can be used to cut aluminum siding. These hand tools look like pliers, but have sharp blades and considerable cutting force. Tin snips are engineered specifically to cut sheet metal, such as the aluminum sheets that are used to make siding. 

Make sure your tin snips are well-sharpened to avoid jagged edges. When not in use, always close and lock the snips. 

• Yellow-handled tin snips. Yellow handled tin snips are designed to cut straight, similar to a pair of scissors. Use this tool for straight cuts, as well as wide, sweeping curves. 
• Green-handled tin snips. Green-handled tin snips can cut in two directions: straight, or to the right.
• Red-handled tin snips. When you need to make cuts to the left, use red-handled tin snips. This tool can also cut straight ahead. 

Tin snips are good to have on hand, as they are also great for cutting vinyl siding.

Nibblers

Nibblers are powerful tool that cuts sheet metal via two highly-vibrating blades. They can be handheld or bench-mounted. Nibblers are best for navigating difficult to reach areas and making small or precise cuts with many directional changes. 

It is difficult to make a long, straight cut with nibblers. For horizontal, lengthwise cuts, you’re better off using tin snips or a power saw.

Power saws have metal blades. When spinning at high speeds and encountering friction, metals react in different ways. Aluminum is one of the trickiest metals to cut. It is relatively soft, but there is a fair amount of material transfer in the processes. In other words, aluminum has a tendency to clog blades. 

Not only do clogged blades increase your costs, they’re also more likely to jam and even shatter. Abrasive blades clog easily, avoid using them to cut aluminum siding. A ferrous blade will cut aluminum (a nonferrous metal). However, non ferrous blades, such as those made of carbide, are the least likely to clog.

A blade with a low tooth count is less likely to clog than one with a higher tooth count. Whatever blade you choose, lubrication is key.  

Conclusion

Cutting aluminum siding is an approachable DIY project that can save you significant sums in installation costs. To make horizontal cuts in aluminum siding, use a table saw. For vertical cuts, a chop saw or radial arm saw is the best choice. For cut-outs, use tin snips and/or nibblers. With each method, measure and mark carefully.