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.

What is the best gravel for a 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.

What size gravel is best for drainage?

In general, you want to aim for ½ inch to 1-inch gravel for drainage. Areas that will see especially heavy flow may need larger gravel. Or, projects without drainage pipes may also need larger gravel. For example, a French drain without perforated pipe needs 1 ½ inch gravel.

Can I use #57 gravel for French drain?

Washed clean stone with an average size of 3/4 inch. This is used as drainage stone inside of French drains and in the back of retaining walls and for gravel driveways.

What stone do I need for a French drain?

The stone should be no less than ¾” and dense (we suggest Granite, or River Gravel) so it will allow good water flow. Lime Rock, although inexpensive, is a poor choice for a French Drain because it will begin to deteriorate over time and eventually begin to pack down and restrict flow.

What is the Best Drainage Stone to Use for Your French Drain? [FRENCH DRAIN MISTAKES]

How much gravel do I need for a 50 foot French drain?

To calculate gravel needed for a 50′ french drain, multiply the length of the trench by the width and depth. If you plan to lay down 4 inches of gravel, multiply 50 feet x 4 inches = 200 cubic feet.

Do you put gravel under French drain?

The old way of installing French drains is to do it without the gravel and the fabric. Without the gravel and the fabric, however, the drain can clog up with sand and soil over time.

What size rock is best for drainage?

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 I use pea gravel 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.

Is pea gravel the same as river rock?

In fact, many people don't realize that pea gravel is actually river rock. It is just a smaller, smoother version of river rock. Pea gravel is widely available throughout the northeast, which makes it one of the most affordable of all decorative stones.

Is bigger gravel better for drainage?

Larger-sized gravel will be more ideal for drainage. Stones with a size of half an inch to one inch across are the right size for blocking debris, yet allow for water flow. Larger rocks won't accidentally become compacted during heavy flows.

How deep should a 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.

Is sand or gravel better for drainage?

It's recommended to place down a few layers of crushed rock or sand underneath the gravel in order to stabilize the drainage surface. When it comes to drainage material layer size, typically a two- to three-inch layer of gravel will effectively deter water buildup.

What is 20mm gravel used for?

Gravel, also known as garden shingle, can be used to finish a variety of garden or landscaping projects including driveways, pathways, rockeries, borders, and water features.

Is crushed rock good for drainage?

Gravel can also help with drainage by breaking up an expanse of hard, impermeable hardscape.

Should I use landscape fabric in 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.

How much pea gravel do I need for 12x12?

Divide the cubic feet of gravel by 27 to get the number of cubic yards of pea gravel needed, such as 36 ÷27 = 1.33 yards. For a 12×12 patio, 3 inches deep, you will need approximately 1.33 cubic yards, or 36 cubic feet, or 2 tons, or 72 bags of 50-Pound of pea gravel.

What are gravel sizes?

The U.S. Department of Agriculture and the Soil Science Society of America define gravel as particles from 2 to 80 mm (0.079 to 3.150 in) in size, while the German scale (Atterburg) defines gravel as particles from 2 to 200 mm (0.079 to 7.874 in) in size.

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 limestone gravel good for drainage?

Gravel and limestone are permeable and porous so they can absorb rain and replenish groundwater. They are also great for drainage purposes which is why they're commonly used in gardens and pathways.

How much rock goes in a French drain?

You would need around 0.72 cubic feet of gravel per foot length of French drain for a typical French drain width of 10 inches and a depth of 12 inches if you're using a 4" drain pipe. On the other hand, you would need around 0.6 cubic feet of gravel if you're using a 6" drain pipe.

How deep should a 4 inch 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.

Can you cover 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.

Does a French drain need an outlet?

A properly designed French drain system does not require an outlet. The water will simply soak into the soil as it flows along the perforated pipe. In fact, a French drain doesn't require an inlet on just one end either. You can construct the drain to accept water along its length, and disperse it underground.

Do you cap the 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.