How to Install a French Drain

Do you have water problems in your basement or crawl space? Installing a French drain can improve or eliminate the water intrusion. I will show you step by step how to install French drains along the foundation of your home.

Last week I wrote an article called How to Install Window Wells”. You should consider installing window wells around your basement windows to help improve water intrusion issues. You will already have the digging done and they are simple to install.


Skill – Intermediate

Time – 8 Hours

Cost – $100-$200


Tools and Materials Needed

Drain Pipe

Perforated Drain Pipe

Couplings and Fittings

Trench Wrap

Stakes

Zip Ties

Washed Gravel

Topsoil

Shovel

Trench Digger (Optional)

Axe (Helpful with roots)

Level

Wheelbarrow


  1. Dig Trench

Dig Trench for French Drain

You can do this by hand like I did, or you can rent a trench digger. I suggest renting a trench digger as it will speed up the process considerably. You will need to make sure you have the whole route of the trench planned and enough drain pipe for the whole route.



  1. Slope Trench Downhill

Slope Trench

The best way to make sure you are routing the water away from your home is to use a level. I only had a two-foot level handy, so I used a 4×4 to help determine the slope of the trench. You could use a four-foot level and you would be ok.

  1. Lay Trench Wrap in Trench

Trench Wrap

The purpose of the Trench Wrap is to keep soil from plugging up your French drain. You will only need the trench wrap the part of the trench that will contain the perforated pipe.

You want the perforated pipe along the foundation. About three feet beyond the foundation you can use non-perforated drain pipe and connect the two with a coupling.

  1. Stake Trench Wrap Down

Stake Trench Wrap Down

You will need to stake down the trench wrap to make sure it stays in place while you fill with washed gravel and your French drain.

  1. Fill Trench with ONE Inch of Washed Gravel

Layer of Washed Gravel

You want the drain pipe to sit on about one inch of gravel.

  1. Lay Drain Pipe in Trench

Perforated Drain Pipe

I recommend using the Perforated Drain Pipe with a Sleeve already on it to go along the foundation and once you get about three feet past the foundation you can switch to non-perforated drain pipe connecting the two with a coupling.

  1. Fill Trench with Washed Gravel

Fill Trench with Washed Gravel

You will now need to fill the rest of the trench in with washed gravel. You will want about three inches of gravel on top of the drain pipe.

  1. Cover Gravel with Trench Wrap

Cover with Trench Wrap

You will now need to take the stakes out of the trench wrap and fold the trench wrap over the gravel so that it overlaps.

  1. Backfill with Topsoil

Backfill with Topsoil

You might be able to use the soil that you dug up for the trench, but I wanted to make sure I had a good slope away from the foundation wall, so I used two yards of topsoil when backfilling.

  1. Install Drain Cover on End of Pipe

Drain Cap

This Drain Cover optional, but I wanted to make sure that I didn’t have anything getting in the pipe and plugging it up. Again, its not necessary but it only costs $2.84 at Home Depot, so why not.

While I had the ground dug up I installed Window Wells, click the link to read my “How To” article. I also installed downspout drains to help get the water away from the foundation.

Good Luck with your project!

If you have any questions leave a comment bellow or send me an email.

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