How to Install Drainage Under a Patio

If water collects near your home, it can cause leaks and cracks in your foundation. Installing a drainage system such as a French drain can guide the water away from your house and to an area in your yard where it won't cause any damage. A French drain runs alongside your home, so if you have a concrete patio in your yard, you'll need to run the drain underneath the patio.

Spray paint
Jackhammer
Safety goggles
Ear protection
Gloves
Hammer
Chisel
Gravel
Drain tile
Landscaping fabric or geo-textile fabric
Concrete
Trowel

Instructions

- 1
  Spray-paint a line on the patio 1 foot away from your house.
- 2
  Tear up the concrete in the space between the line and your house. Begin at the line and work in toward the house, using a jackhammer. Remove the chunks of concrete as you break them up. Use a hammer and chisel to remove the concrete when you get close to the house. You can rent a jackhammer at an equipment rental facility.
- 3
  Remove all of the concrete from the trench, and dig into the ground until the trench is 12 inches deep. Slope the bottom of the trench down toward the area where you want the water to drain.
- 4
  Pour 2 inches of gravel into the bottom of the trench, and rake the surface smooth.
- 5
  Cover drain tile with landscaping fabric or geo-textile fabric. Drain tile is plastic pipe with holes in it that allow water to pass through. Covering it in the fabric can help prevent the drain tile from clogging with dirt carried by the water.
- 6
  Place the drain tile in the trench, centering it between the foundation wall and the patio.
- 7
  Fill the trench with gravel until you're approximately 2 inches from the surface.
- 8
  Prepare a batch of concrete, following the manufacturer's instructions on the packaging.
- 9
  Fill the trench with the concrete, smoothing the surface with a trowel.

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