Quick Answer: What Size Rock Is Best For French Drain?

Does a French drain need to be sloped?

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..

Does a French drain need an exit?

Most descriptions of a french drain involve a slotted or perforated pipe, a trench, geotextile fabric and gravel backfill. To operate properly, the drain must have adequate slope and a place to open onto the ground, into a drain pipe or somewhere else where water can exit.

Can you cover a French drain with dirt?

The simplest drain is a classic French drain, which is nothing more than a trench filled with coarse stone or gravel. A 2–4% slope is adequate to quickly move water away from trouble areas. The drain can be left open or, if aesthetics are a concern, can be covered with a couple of inches of topsoil and sod.

Can you put a French drain under pavers?

Installing Drains A French drain system at the edge of your paver patio can be done on your own or hired out to the landscaping professionals. The water can be delivered to your flower beds or garden area.

Can you use landscaping fabric for French drain?

A landscaping French drain is a gravel-filled trench that’s lined with landscape fabric to keep soil and silt out of the gravel.

Do French drains work in clay soil?

A french drain in clay soil can be very effective though the soil conditions need to be taken into account in order to ensure that the french drain design is suitable. This includes the infiltration characteristics of the clay soil and the installation details.

What is the difference between a French drain and a trench drain?

The terms rhyme, they both involve trenches, and French drains aren’t really French. The defining difference is very simple, however: Trench drains are surface structures while French drains are subsurface ones. Let’s look at how they both work to keep water flowing offsite.

How much rock do I need for a French drain?

What size gravel do you use for a French drain? French drain gravel should be washed three quarter inch minimum and as large as 1 ½ ” crushed stone. The upper 12 inches above the pipe shall be filled with native soil, to avoid having crushed stone over the perforated pipe that could damage the pipe.

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

polypropylene soil fabricQuality woven, pure polypropylene soil fabric has always been preferred for French drains, soil stabilization, ditches, and pipe-in-gravel, chamber and mound septic leach field systems.

Do holes go up or down in a French drain?

When you lay your PVC pipe, the rows of holes should always be facing the downward position. You want to keep the water level in your French drain as low as possible at all times, and you can’t achieve this if the holes are facing upwards or sideways.

How deep should you dig for a French drain?

About 8 inches to 2 feetFrench 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.

Can I use river rock for French drain?

Hard rocks such as granite or river gravel prove viable options for a French drain because they won’t break down over time as much as other rock varieties, such as sandstone and limestone.

Is pea gravel good for drainage?

Since it has a smooth finish, pea gravel is also regularly used for walkways, dog runs, playgrounds, patios, and a variety of other high-traffic areas. Like crushed stone, pea gravel can also be used for underground projects, such as drainage and pipe bedding.

What is the best material for drainage?

Nearly every book or web site on container gardening recommends placing coarse material at the bottom of containers for drainage. The materials most often recommended for this practice are sand, gravel, pebbles, and pot shards.

What size gravel is best for French drain?

For the best drainage, look for coarse washed rock (gravel) that is screened, with a stone size of 1/2 to 3/4 inch. Smaller rock with fine particles could clog the holes of the drain pipe. Pea stone works, but the smooth stones settle together and don’t move as much water as coarse rock.

Can a French drain be too deep?

For a slab foundation, you want the pipe below the slab or about 2 feet. If you have a basement, you can install the French drain 6-feet deep or more depending on the depth of your basement.