How far down should French drain be?

French drain depth: About 8 inches to 2 feet deep should be sufficient for many water-diverting projects, though related systems, such as those built around foundations and sub-ground living spaces, as well as the bases of retaining walls, may be deeper.

How shallow can a French drain be?

The trench should be about 18 inches deep and 9 to 12 inches wide. French drains need to have a slope of at least 1 percent, so the force of gravity will work for you. This means that the drain should slope down a total of at least one inch for every 10 feet of pipe.

How far down should a drain pipe be?

Maintaining a depth of 12 to 18 inches is best for drain pipes, but the depth of the pipe may vary in order to maintain a downward slope, which is critical for proper drain functioning.

What angle should a French drain be?

All of your drain pipe (with one exception) must slope slightly downhill. Usually 1/8" per foot is plenty for drainage, this is the same as the commonly recommended 1% slope. Note that I said the drain pipe must be sloped rather than the French drain.

Can you cover a French drain with dirt?

Can I cover a French drain with dirt? Because a French drain has holes throughout the pipe which allow it collect water, you should not install dirt on top of the drain pipe. Installing dirt will clog the pipe and the holes, rendering it useless.

How Deep

What size gravel is best for French drain?

Use Natural 1-1/2" round rock for best drainage. Washed rock is ideal. Avoid small pea gravel as the spaces in between stone is smaller minimizing flow rates. Avoid Crushed Rock (minus) that compacts and has "fines" that will clog pipe inlets.

Why do holes point down French drain?

If the pipe is placed upside down, with perforations towards the top of the pipe, it's not like it wouldn't work — the pipe performs better and transports water quicker if they are pointing down.

What is the best pipe to use for a French drain?

French drains are typically constructed with black corrugated pipe, but there are arguments that favor using white PVC pipe for the job, as well.

How do you Slope a French drain?

A French drain needs a slope of no less than 1%. That means from the highest point of the drain field all the way to the drain exit, the system should slope at least 1 inch for every 8 feet of length.

How much gravel do I need for a 100 foot French drain?

To calculate gravel needed for a 100′ french drain, multiply the length of the trench by the width and depth. If you plan to lay down 4 inches of gravel, multiply 100 feet x 4 inches = 400 cubic feet. Since each bag equals 1.5 cubic feet, divide 400 by 16 to determine the number of bags you will need about 26 bags.

How do you install an outdoor French drain?

Add 2 to 3 inches of gravel to the bottom of the trench. Lay the drain pipe in the trench, with the drain holes facing down. Cover the drain pipe with gravel to within 2 to 3 inches of the top of the trench. Fold the excess landscape fabric over the top of the gravel.

Should French drain be below frost line?

Tip #3: Place French drain below the frost line.

A properly installed French drain will begin at the depth of the base of the perimeter beam and is installed with a 1% minimum slope (1 inch in 8 feet). This is usually below the frost line.

Is PVC or corrugated pipe better for French drain?

Know which material is being used when having a drain installed on your property. We will state unequivocally right now that PVC is the far more durable material. We highly recommend it over corrugated pipes.

Can I use landscape fabric for French drain?

Non-woven geotextile fabric is the best choice for drainage applications where water flow through (permeability) is the main concern. Non-woven landscape fabric is commonly used in French-drains, drain-fields, and erosion control.

Do I need gravel for solid drain pipe?

In this system, the pipe is solid, and not perforated, so there's no need to provide gravel for drainage along the length of the drainpipe. One advantage of a smooth-wall pipe is that it will drain water quickly, and if it gets clogged, you can use a drain snake to clean it out.

Can a French drain be too deep?

French drain depth: About 8 inches to 2 feet deep should be sufficient for many water-diverting projects, though related systems, such as those built around foundations and sub-ground living spaces, as well as the bases of retaining walls, may be deeper.

How many years does a French drain last?

When enough sand, clay or silt gets past the fabric, the gravel spaces fill and the effectiveness of the french drain ends. This is why most experts state that a French drain is not a long-term solution to a drainage problem: You have to dig it up and reinstall it every eight to 10 years.

Is pea gravel good for French drain?

Do NOT Use Pea Gravel, Pea Pebble, Pea Stone When Building a French Drain. When building a French drain, you want to use a coarse rock that has been screened and washed. The rock that you see in this French Drain is 3/4″ and larger. You end up with large voids that'll move far more water.

Do you cap one end of a French drain?

Cap the end at beginning of the system. Level rock 4 inches from the top of the trench. Note: If you just dump rock on top of the pipe, it will shift to one side of the trench. Make sure to keep it in the middle of the trench.