There's a shed near the side of the house with a roof that's pitched to shoot water at the house's foundation. That side of the house also has no gutters. There's a very slight grade to send water towards the front of the house. House is brick veneer, on-slab.

How can I build a drainage system to carry water away from the foundation?

4 Answers 4


Here is a pretty quick explanation.

  1. Starting from where the water will enter the drain and ending where the water will flow out, dig a ditch that's about 10 inches deep and 6 inches wide. Keep in mind that you will need to dig deeper if your starting point slopes upward.

  2. Lay about 2 inches of rock into the trench before placing the pipe lengthwise into the ditch.

  3. Cover the pipe with another layer of rocks, again about 2 inches.

  4. Fill in the remaining space with soil and then plant some grass.

Here is a pretty good video, which also shows it's a good idea to add a clean-out.

They also say you should not use flexible corrugated perforated plastic drain pipe, because it cannot be cleaned like rigid pvc can be.

  • 6” wide trench? What is the diameter of the pipe?”
    – Lee Sam
    Commented Apr 28, 2019 at 17:36
  • You don’t “clean” the inside of a perf pipe. The problem is ALWAYS plugged holes...especially if no fabric and 1” coverage on each side of a perf pipe.
    – Lee Sam
    Commented Apr 28, 2019 at 17:39
  • I don’t like corrugated perf pipe because it doesn’t lay flat. It always “curls” in the trench.
    – Lee Sam
    Commented Apr 28, 2019 at 18:08

Here's another article about a French / Trench drain:

Basically the same idea, except he doesn't recommend lining the ditch with fabric or putting a sock on the pipe. He does recommend using rigid perforated pipe instead of the corrugated pipe with slits in it.

  • I like the idea of omitting the fabric (expensive!). Great link. Commented Nov 19, 2010 at 5:25
  • 5
    @Steve - I dug a French drain on the uphill side of our house 30 years ago. I don't think we even had fabric back then. It worked great - for the first 10 years. I've had to use a sump pump ever since. That crushed rock isn't good for much once it's all silted up.
    – Ed Staub
    Commented Sep 24, 2011 at 13:38

Depending on the area , and your costs, you could also just buy a prefabricated french drain and save yourself some times. Your BIG local hardware store would have something like this:

enter image description here

  • Heard these are not very good...
    – mang
    Commented Jun 4, 2019 at 20:47

There are many French Drain videos on YouTube. My opinion is watch the ones by French Drain Man for commercial grade work that lasts. Apple Drains great also for homes in the South where freezing is not an issue. The filter wrap over pipe is controversial as it substantially reduces flow. FTM puts it outside the gravel to prevent silting. The prefab DIY stuff surrounded by Styrofoam peanuts is not used by Pros and uncertain.

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