How to Connect a Downspout to a French Drain

Place your shovel into the ground where you want the downspout drain to intersect your current French drain. You can also place it at the end of the drain, if you are extending the drain to reach your downspout. Step down on your shovel to create a 1-foot-long cut in the grass. Repeat the process to create a 1-foot square cut in the grass, then pull up the sod and move it to one side.

Continue to remove the sod until you have a line going to your downspout.

Dig a trench where you removed the sod. The trench depth must equal the depth of the French drain.

Create a slope on the bottom of the trench so the part directly under the downspout is a few inches higher than the part that connects to the French drain. Use a level to ensure that the entire stretch of trench is sloped, then use a tamper to tamp down the bottom.

Place a 2-inch layer of 1-inch washed and rounded gravel along the bottom of the trench.

Crimp the bottom of the downspout with a crimper. Simply place a section of downspout between the blades of the crimper and squeeze the handles. Repeat until the entire bottom of the piece is crimped.

Slide a downspout elbow over the bottom of the downspout, with the elbow angling in the direction of the trench. Screw the elbow into place using two 1/4 sheet metal screws. If your downspout is already angled toward the trench, skip this step.

Cut a piece of downspout material with a hacksaw so it is long enough to reach from the bottom of the elbow you just installed to the bottom of the trench. Crimp the bottom of this piece and attach another elbow, this time angling the downspout so it is horizontal to the ground. Attach this whole section to the elbow at the bottom of the downspout. Make all attachments with two 1/4-inch sheet metal screws.

Wrap the landscaping fabric around the perforated pipe and place the pipe into the trench with the perforations facing down. Insert the end of the downspout into the end of the pipe. Place the other end of the pipe against the end of the pipe that was already in your French drain. If you are intersecting an existing French drain, simply have the new pipe end 2 or 3 inches away from the existing drain.

Fill the trench with the gravel, up to 2 inches below the lawn surface. Put the sod that you removed back in place to hide the drain.