How to Cut Downspout?

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Gutters protect your home from moisture accumulation and direct the flow of water for appropriate drainage. The downspout is a critical part of this equation, but can easily degrade or become crushed or damaged. When this happens, there’s no need to call a professional — you can cut a new downspout and crimp it for insertion into an elbow joint, using the instructions below. 

How to Cut Downspout?

Downspouts are usually made from vinyl or aluminum. Cutting gutter downspouts is most easily accomplished using tin snips or a jigsaw. 

Gutter and downspout on an icy roof.

There are two reasons to cut downspouts. One is to trim away crushed, broken, rusted, or damaged pieces of the existing downspout. Tin snips are an easy way to cut through the broken material to trim away the excess. 

When you need to start the cut in the middle of the downspout, you can still use tin snips, but some of the material will be wasted. To avoid wasting material and accomplish the job more quickly, consider using a jigsaw instead. 

Learn the entire process for cutting gutters in our comprehensive article. Here we’ll focus specifically on cutting the downspout.

Trim Old Downspout Ends with Tin Snips

When the bottom of your gutter downspout gets torn and ragged, it ceases to function properly and can damage your home’s foundation. The easiest recourse is to cut it off and attach a new bottom section. 

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  1. Put on protective gloves. Downspouts with jagged edges can easily cut your hands. A pair of tight-fitting cut resistant gloves makes this project easier and safer. 
  2. Mark the cut. Place a carpenter’s square aligned with the side of the gutter downspout, and draw a line along the other arm. Rotate the downspout to extend the line around the entire circumference. 
  3. Snip away the excess. Use yellow or red handled tin snips to cut through the broken edge of the downspout, up to the mark you made in the previous step. Then, rotate the tin snips to cut along the pencil or permanent marker line. Rotate the gutter as you cut, pulling the waste material up and out of the cut path. 

Cut New Downspouts Using Tin Snips

  1. Protect your hands. When cutting out sections of downspout, it’s easy to trap or pinch your fingers. Bending the unused gutter material out of the way is a good way to get a nasty cut. Avoid injuries and delays to your project by donning a pair of protective gloves before starting this project. 
  2. Measure and mark. Make a mark on all four sides of the gutter downspout to indicate how long you want the section to be. Use a straightedge or carpenter’s square to extend a line through the four marks. You should have a square, straight line all the way around the downspout when you finish with this step. 
  3. Cut into the gutter downspout. Place the blade of a utility knife on the waste side of your cut line. Position the knife at about a 45 degree angle and rock it back and forth to make a diagonal cut about two inches long.
  4. Circle back to your cut line. Insert green-handled tin snips at the far end of the diagonal cut made in the previous step. Cut an arc through the waste side of the downspout, circling back to your marked cut line. 
  5. Separate the section. Using the green-handled tin snips, make a few cuts along the cut line. Then, switch to your red-handled tin snips and cut parallel to the cut line on the waste side of the material, releasing a few inches of downspout material. Bend the material up and out of the way. 
  6. Repeat. Use the green-handled tin snips to cut another few inches. Mirror this cut with the red-handled snips. Bend the material up and out of the way. Continue on in this manner, rotating the downspout, until the section has been removed. 

Cut Downspouts Quickly With a Jigsaw

Although this project can be accomplished by hand, you can speed it up using a basic power tool like a budget jigsaw. Jigsaws make quick and accurate cuts, and are plenty powerful enough for the relatively soft materials that make up gutter downspouts. 

  1. Measure the downspout length. If you’re replacing a broken or worn piece of gutter downspout, it’s easiest to remove the existing downspout and measure its length. If you’re installing a new downspout, measure from the insertion point at the eaves of your roof down to a few inches above the ground. You’ll want to leave room to install the outlet and direct the flow of water once your gutters are up and functioning. 
  2. Draw a cut line. Use a marker or carpenter’s pencil and a square to draw a straight, even line around the downspout. Wrap tape around the line on the waste side if you’d like a visual guide while cutting. 
  3. Plan your cut. Prop or position the downspout so it is sturdy and supported parallel to the ground or floor. Two sawhorses work well. You may want to ask a friend or helper to hold the downspout steady while you cut, as clamping this material can be a bit tricky. Check the path of your blade and make sure there is nothing in the cut path. 
  4. Protect your eyes and skin. Wear long sleeves and heavy pants to protect your skin from any metal splinters that may be generated during the cutting process. Protecting your eyes is a must, use safety glasses or a full-face shield. Cut-resistant gloves won’t withstand direct contact with a knife, but they are excellent for avoiding scrapes and scratches. 
  5. Install an appropriate blade. Downspouts are usually made from vinyl or aluminum. Both of these materials can be easily cut with a cheap jigsaw, provided you install an appropriate blade. High speed steel (HSS) blades will work, as will bi-metal blades. You could also use a carbide tipped blade, but it’s not necessary. Look for blades with between 18 and 24 teeth per inch (TPI)
  6. Connect to power. If your jigsaw is battery operated, insert the battery pack. For electric jigsaws, connect to an appropriate GFCI outlet. 
  7. Make the cut. Place the shoe of the jigsaw on the top surface of the downspout, with the blade against the side closest to you. Squeeze the trigger on the jigsaw to start the flow of power. Move the jigsaw forward along the cut line. 
  8. Stop and rotate. When you get to a corner, stop the jigsaw and remove the blade from the cut. Rotate the gutter one-quarter turn, so the surface you’re cutting is always facing up. Continue cutting until you reach the next corner. 
  9. Clean up. When you’ve finished the cut all the way around, power off and unplug the jigsaw. Store it in a safe location. Use a brush and dustpan to sweep up any metal shavings or splinters. Discard them, along with any downspout scrap. 

How to Attach Downspouts After Cutting

Once you’ve cut the length of the downspout, the next step is to prepare it for insertion into the elbow joint where it meets the gutter. 

Open downspout near the building stairs.
  1. Get a crimping tool. Crimping tools are fairly inexpensive, but they also don’t get used much. If you can, borrow a crimper from a friend. You’ll want a five-bladed crimping tool for this project. 
  2. Protect your hands. Use sturdy but tight-fitting gloves to allow you to handle both the sharp edge of the downspout and the plier-like crimping tool. 
  3. Orient yourself. Place the downspout on a table or workbench with the end hanging off one side. Position yourself at the top of the downspout. 
  4. Crimp. Insert the edge of the downspout into the jaws of the crimping tool. Make sure your fingers, hands, gloves, and sleeves are clear of the crimper jaws. Squeeze the handles together. 
  5. Keep going. Move the jaws of the crimper along the edge of the downspout, and repeat the crimping process. When you get to a corner, rotate the gutter downspout, and crimp the next edge. Overlap each crimp slightly. 
  6. Inspect your results. You should have narrowed the opening at the top of the downspout, making it narrow enough for insertion into the elbow joint. 

Conclusion

Cutting downspouts can be accomplished with tin snips or a jigsaw. A five-bladed crimper is used to prepare the cut downspout for installation into an elbow joint. Measure and mark carefully, then wear gloves to protect your hands during this project. 

Ellenkate grew up on job sites run by her family’s construction company. She earned her theater degree from The Hartt School, a prestigious performing arts conservatory in Connecticut. Her design and DIY work from her Chicago loft was featured in the Chicago Reader and on Apartment Therapy.