Fix-It Chick: Build a French drain

French drains are named after Harold French, the Massachusetts farmer who invented them. They are basically channels filled with gravel that direct water down and away from your home and property. Installing a French drain can be back breaking work, but it is a relatively easy fix to a soggy problem.

Step 1: Plot the course of the drain using wooden stakes and string.

Step 2: Use a line level to level the string between stakes. Use a Sharpie to mark the string line position on the stake.

Step 3: Drains should slope 1/8-inch per foot of run. Measure the length of the string between the first two stakes, rounding to full feet. Divide this number by eight. Measure down this number of inches from the string line on the further stake and mark that position too.

Step 4: Continue to measure and mark the stakes along the full run of the drain.

Step 5: Dial 811 to call Dig Safe and schedule a date for them to come out and mark the presence of all utilities in or near the digging area. Check with the local government to ascertain the drain plan adheres to local zoning codes and regulations.

Step 6: Once permits are acquired and utilities are marked, dig a trench along the string line. Start at the end of the drain and work backward. Save the topsoil to spread later. Dispose of the subsoil one way or another.

Step 7: Use the string line as a guide to dig the drain. The trench should be 18–24 inches deep and 6–12 inches wide. Wider trenches are easier to dig and drain better. Measure down from the marks on the stakes to maintain the proper slope.

Step 8: Once the trench is dug, line the bottom and the walls with permeable landscape fabric. Pin the fabric into place, leaving 10 to 12 inches of overhang along the sides.

Step 9: Fill the trench with gravel, not limestone. Installing a run of rigid perforated drain line atop the first 3 inches of gravel will facilitate drainage even more. Make sure the perforations are facing down and top the pipe with 6 inches or more of gravel.

Step 10: Fold the overhanging portion of landscape fabric over the top of the gravel. Pin it into place.

Step 11: Top the drain with decorative stone or cover it with left over topsoil.


Richard Ballard 3 years, 10 months ago

This is all well & good.

Up to the part about using perforated drain line wrapped in landscape fabric.

I did exactly that 15 years ago. And have been plagued with a stopped up French Drain for the last 10 of those years.

Landscape fabric simply Will Not stop tree roots from growing through every hole in the perforated pipe trying to get to the water.

And stopping it up completely every few years.

Use white PVC pipe, and cement the joints like a sewer line. And a pop-up on the end to let the water out. Otherwise, you will have problems in a few years if there are any trees within 150 feet in any direction!

Trust me! BTDT!

Finally had to dig it all up & do a do-over with white PVC to stop the tree root clogs every year.

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