How to Put a Downspout in an Existing Gutter

A properly installed gutter system collects roof water and directs it into a downspout that carries it away from the foundation of the home. If the downspout is missing or damaged, water pools below the gutter instead of flowing away from the building. To install a downspout on a newly installed gutter, you must first determine where to cut a hole in the flat bottom of the gutter to insert an outlet that will feed the water flow out of the gutter and into the downspout.


Things You’ll Need:

  • Cordless drill
  • Marker
  • Outlet
  • Gutter snips
  • Pop rivets
  • Pop rivet gun
  • Gutter elbow
  • Downspout
  • Downspout straps

Mark the desired location of the outlet on the flat bottom inside the gutter. The gutter is slightly tilted in one direction so that water will flow to the outlet instead of collecting in the gutter. Place the downspout outlet on the low end of the gutter. Look at or measure the visible fascia board area under each end of the gutter to determine which is the low end. The end with less fascia board showing is the lower end of the gutter. Make sure there are no obstructions on the wall, column or post where you plan to attach the downspout.

Lay the outlet piece inside the gutter over the marked downspout location and use a marker to trace the bottom of the outlet to outline the cut you will make.

Cut along the traced line, using gutter snips. The hole will be smaller than the diameter of the downspout, but large enough to accommodate the bottom diameter of the outlet. Use a hole punch in the corners and then a jigsaw to cut the gutter if gutter snips are not available.

Insert the outlet into the hole inside the gutter section and secure its upper lip in place with 2 to 3 pop rivets.

Measure from the center of the outlet straight back to the wall or column where the downspout will be attached. Subtract 6 inches from this measurement to account for the addition of two elbows. Cut a section of downspout to this length.

Attach one elbow to each end of the downspout section to form an “S” shape. Make sure the higher section always inserts inside the lower section as you make each attachment. Secure the elbows to the shortened downspout section with pop rivets. This “S” shaped section is called a “sweep.”

Place one end of the sweep over the outlet that extends from the bottom of the gutter. Secure the sweep to the outlet with pop rivets.

Add downspout sections as needed down the wall to the ground. Connect each section using pop rivets. Downspout is sold in 10-foot sections. The height of your gutter will determine the number of sections you need. Slide the end of the higher section inside the lower all the way down. Insert pop rivets where the sections overlap.

connect an elbow over the end of the downspout to direct the flow of water away from the building. Secure the elbow to the downspout with pop rivets.

Wrap downspout straps around the downspout at 3-foot intervals down the wall. Hold the ends of the straps together on one side of the downspout. Drive one screw through both ends of the strap and into the wall to hold the downspout in place.

Tips & Warnings

Remove the gutter section before cutting the hole and installing the outlet if desired.

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