How to Cut Downspout Gutter to Length

Most homeowners never find themselves learning how to cut downspout. Why’s that? Because that’s what plumbers are for. 

You might be nervous about cutting downspout for the first time, but it’s simple once you find the right instructions.

Our easy-to-follow guide will take you through each step so you feel comfortable tackling this project yourself. If you ever find yourself in this situation again, you’ll have no problem knowing how to cut aluminum downspout yourself.

What Tool Do You Use to Cut Gutters?

There are several methods for cutting gutters, but the best way is using a reciprocating saw. That said, you’ll likely need a budget set of tin snips for some of them tricky angles. 

This saw blade is designed for cutting metal and will finish the job in no time. With the rest of your materials, the reciprocating saw will help you to install the new downspout and remove the old one from your gutter system to form a better connection to your roof. 

Before you start cutting, remember to wear gloves and use eye and ear protection to keep yourself safe.

What You’ll Need:

Luckily, cutting the gutter downspout from your roof doesn’t require a professional’s arsenal of tools, and they can be easily found.

Once you have all the tools for cutting below, you’ll be ready to get the job done. What you’ll need is:

How to Cut Downspout With a Reciprocating Saw in 4 Steps:

After you have obtained all the necessary tools and materials from your home or local hardware store, it’s time to begin the project.

Aluminum downspouts can be cut in just four simple steps using a reciprocating saw. All the cutting will be easy once you start. Below, we’ll show you how.

Step 1: Measuring Gutter Downspout

The first step to any home project is measuring the area. You need to find out how large you need the piece of downspout to be before you begin cutting from your roof.

Mark your measurement with a line on the downspout wall with a carpenter’s pencil or something easy to see. You want to measure from the bottom of the main gutter to the ground. If you’re simply replacing the downspout, you can use the damaged one as a template for the new one after removing it from its spot near the ground. 

You should also measure a downpipe clip centrally over the line mark on the wall you made for when you drill the fixing holes. The downpipe clip will help you fit the downpipe into place later. Measuring the downpipes is done by considering the roof area.

If you’re unsure how much you need or doing other gutter renovations in addition to the downspout, consult a home guide to help you before making the first cut or mismeasuring the downpipes.

Step 2: Attach a Metal Cutting Blade

Before using a reciprocating saw, you need to attach a metal cutting blade. This is done by releasing the shoe and then hooking the blade into the locking apparatus.

Then, you’ll need to twist the blade in and put the shoe back into place to work with the blade. Now you’re all set to begin cutting downspout.

Step 3: Cutting the Downspout Gutter

Cutting the downspout is easy, but you want to take your time. If you are working with a new downspout, work slowly to carefully cut one side off the wall at a time. Rotate the downspout sections 90 degrees to the other side, then cut through the next side. Taking the time and working through it section by section will produce a clean cut.

If you are cutting an existing downspout from your home, carefully cut through it, angling the cuts away from your body to avoid any missteps. The material is soft and pliable, so achieving a perfectly clean cut along the length should be easy as long as you do not rush.

Step 4: Crimping the Aluminum Downspout

Crimping the downspout will make it fit inside the elbow without any problems. For the step, you will want to purchase or borrow a crimping tool. If you attempt to crimp the downspout yourself with improvised materials, you will most likely crush or deform the end that needs to fit precisely into the elbow, and the drain won’t work.

Crimping each corner of the downspout with a crimping tool will help create an end that will fit perfectly inside the length of the elbow to create the finished look you want to achieve from your roof to your basement.

Step 5: Attaching the Downspout (with sheet metal screws)

The final step is to connect the downspout to the elbow that goes downward from the gutter. Climb the ladder to work the downspout into the elbow along the undercut side.

Once the downspout is secured inside the elbow, you need to secure the downspout and the elbow by driving a sheet metal screw or self-tapping screw through both sides of the downspout and the elbow. Ideally, you’ll need either a Phillip head type of screwdriver or an impact driver.

Next, you need to install an elbow at the bottom of the downspout to create a proper drain. Assemble it at ground level. Fit the elbow into the bottom of the downspout, then secure it with more screws, just as you did at the top. When you are attaching sections of metal downspouts, you will use gutter sealant.

Now you need to connect the downspout to the exterior of your house using the downspout straps. Use one strap for about every eight feet. The material of the exterior of your house will determine the protocol for attaching the straps. If you are unsure which method is optimal for your house, you should consult someone at the hardware store before you begin.

Once the straps are attached to your house, wrap the straps around the downspout, then drive more screws through the straps and into the downspout once more to get the perfect drain.

Pro-Tip for Cutting Aluminum Gutters:

If you are cutting gutters that are attached to your home, place a board or piece of plywood between the section of the gutter and your home where the cut will be made.

This will protect your home from any damage when cutting quickly.

3 Methods to Avoid When Cutting a Downspout

Gutter work can turn into a messy job if the wrong tool is used or, more importantly, used incorrectly. If you are installing a new gutter, I’d recommend playing around with them with some offcuts before taking to that section of the downspout.

1 | Tin Snips

A simple pair of tin snips or aviation snips are less powerful than other options fit for the job, but they will move slower and therefore yield more precise cuts. You have to guide the tin snips by hand, so you have more control over the movements. Tin snips are not ideal because they can puncture the gutter or create a jagged and messy tool for cutting metal downpipes.

If you choose to use this tool, you want to measure the mark for the fixing holes at one corner and puncture a hole, which is unnecessary when using other methods. You will have to cut alongside the outside line and leave space for the lap joint intact. Once you make the hole, you need to later enlarge that hole or make more.

2 | Circular Saw

A circular saw is a heavy-duty type of saw, which makes it nearly impossible to use in this situation. You could install the blade backward to use it, but it’s not worth the effort. The saw will most likely crush the gutter or cut too much off, rendering the part useless.

3 | Hand Saw and Utility Knife

Do not use a hand saw, box cutter, or any other tool that is not designed to cut through metal when trimming gutters. This will slowly create a mess and damage the blade. Choose a tool equipped with a metal cutting blade handy in your home or at a nearby hardware store.

The 5 Best Tools to Cut a Downspout

The reciprocating saw is the most versatile for cutting through the gutter because it is powerful, but it is not the most precise.

Below are a few power tools we recommend if you are cutting a vinyl or aluminum gutter, ranked from the best to worst for the project.

1 | Miter Saw

The miter saw or chop saw makes clean, precise cuts in aluminum downspouts. If you’re installing a new downspout, equip the power miter with a carbide blade. Repeat the process. Start by making a mark before making the perfect cut. The miter saw is great for repairing or installing the downspout and gutter system.

2 | Dremel

A Dremel equipped with a cutoff blade will also get the job done. Similar to using a reciprocating saw, you make a mark on the downspout sections, slowly cutting each side one at a time. The Dremel makes a precise cut, making the gutter material easier to crimp and install.

3 | Jigsaw

If you fit a jigsaw with a metal cutting blade, you will repeat the same procedure as using a reciprocating saw. The jigsaw is less powerful than the reciprocating saw, but is more precise because you will have to guide the saw slowly by hand.

4 | Reciprocating Saw

The reciprocating saw is considered the best tool for cutting downspout and gutter material during demolition. The reciprocating saw may not be as precise as some of the other tools, but it will get the project done quickly.

5 | Hacksaw

The hacksaw creates a relatively precise cut, but it is slow to work with and will require more manual effort. For smaller projects, the hacksaw can cut through the gutter quickly but isn’t nearly as efficient as other options.

The Bottom Line

If you had never heard of cutting downspout until today, you’re not alone. Even some of the most experienced home DIYers have never had to cut downspouts before.

Fortunately, this task is straightforward once you find the right guide or popular articles to help you navigate the steps and acquire the necessary tools organized for the job.