Connecting your downspouts to french drains using the Flex Grate Downspout Filter


The main purpose of the french drain is to direct water from your roof to a source away from the house, helping to avoid foundation and landscape issues. So when the water from your roof isn't making it into the french drain to begin with, that’s a problem.

What if the water is making it into the french drain, but it’s bringing along large amounts of debris such as sticks, leaves, pine needles, and more? This is a problem as well because you will end up clogging the french drain and will most likely need to call a professional. If this is already the case, turn to a trusted company like Palmershine!


Now, If you are looking for a quick and easy fix, the Flex Grate Downspout Filter is a great option. It directs the water into the french drain but only after filtering all large debris out of the way, preventing clogs in the system.

By following along with the steps below, you can easily install the Flex Grate Downspout Filter with little to no experience.


What you will need:

  • Flex Grate Downspout Filter

  • Tin Snips or Scissors

  • Power Drill

  • 3/4 " Self Tapping screws

  • Hex Driver (possibly Phillips depending on what was used previously)

  • Black Duct Tape

Approximate Time: 15 minutes

Step 1: Using your drill and a hex head nut driver, detach the french drain extender from the downspout or remove any obstructing pieces that may prevent easy installation. Most gutters and downspouts are made of aluminum and will use a self-tapping screw, which is most often a hex head top.

Step 2: Hold the Flex Grate Downspout Filter off to the side of the downspout with the bottom of the downspout about 2 " lower than the top of the filter. Next, mark a line on the french drain extender where the bottom filter sits. Usually a couple of inches off of the ground.

Note: this measurement does not need to be exact since the filter has an accordion-style adjusting extender to fit most lengths.

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Step 3: Using your tin snips or scissors, cut down the length of the french drain extender to where your measurement is. Once you get to the measurement, turn the snips sideways and cut on the line you marked. Initially cutting down length-wise will make it easier to cut sideways at your mark.

Note: I eyeballed the measurement since I knew I could adjust the bottom of the filter if need be.


Step 4: Slide the Flex Grate Downspout Filter up around the bottom of the downspout about 2 ". The bottom of the filter should be pressed down on the french drain extender. Now, using your drill and a hex head driver, fasten a self-tapping screw through the guide hole on the side of the filter or wing (like in the photo, depending on the width of the downspout) and into the side of the downspout.


Step 5: Cut a 2 " slit in the top of the french drain extender. Then wrap the top of the extender around itself in a "cone" like shape. This shortens the circumference of the french drain extender and allows the filter to slide over the top of it. Using your drill, fasten a self-tapping screw through the fold to hold it in place. (1).jpg

Step 6: If needed, carefully extend the "accordion" part of the filter and slide over the top of the french drain extender about 1 1/2". Then wrap the joint with a piece of 3 " wide black duct tape.

Note: Be careful when extending the filter not to pull too hard and break the "wings" which attach the filter to the downspout.

Your Flex Grate Downspout Filter is now installed!

Routinely check the filter during fall and spring months to make sure it is not clogged, causing it to redirect water out of the french drain. Also, locate the end of the french drain and make sure water is flowing freely through it before the installation to ensure it is not clogged.



Properly taking care of your gutters and french drains by routinely cleaning them is the first step to prolonging their life and maintaining a healthy water channeling system.

If you need any help installing the Flex Grate Downspout Filters, or cleaning your gutters and french drains, reach out to the professionals at Palmershine Window Cleaning Services.

Palmershine specializes in window cleaning, gutter cleaning, pressure washing, and window screen repair services and is always ready to serve you!


  • Owner, Nick Palmer
  • Palmershine Window Cleaning Services
  • 720-380-9574