How Much Gravel For French Drain

How much gravel do I need per foot of 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.

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

The volume of the drain is the volume of the “box” that is 100 ft long by 6 inches by 18 inches. That’s 1200 x 6 x 18 = 129600 cubic inches. The difference between these will be the volume of gravel you need. Thats 129600 – 15080 = 114520 cubic inches.

Do I need gravel for 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.

How do you calculate gravel for drainage?

Deduct the volume of the pipe from the volume of the trench. The result is the volume of gravel required to fill the drain. Gravel is sold in cubic feet or cubic yards, so round the value up to the nearest whole unit. One cubic yard of gravel is 27 cubic feet.

How much dirt is needed to cover a French drain?

How deep should a French drain be? A French drain should be at least 6-8 inches deep to protect it from erosion and digging. However, the depth of a French drain will vary and may need to be several feet under the ground depending on the slope needed to ensure water flows properly through the drainage pipe.

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

How much gravel do I need per foot of 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.

How deep should a 4 inch 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.

Can you make a French drain with just gravel?

Installing the Drainage Pipe and Gravel To make your French drain last a long, long time you need to use these following items: Clean or washed gravel (not crushed limestone – it becomes cement like) Permeable landscape fabric (they kind water passes through).

What is the best gravel for a 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.

Can I use pea gravel in a French drain?

For a French drain without a perforated pipe, opt for even larger gravel, such as 1 1/2 inches across. Smaller gravel such as pea gravel would not allow sufficient water flow. No matter what the gravel or stone, opt for washed varieties, otherwise fine dust and particles may hinder or even stop water flow.

What size rock is best for French drain?

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.

How much slope does a French drain need?

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 much is a French drain per foot?

According to Fixr, the average French drain costs $4,500. An exterior drain located fairly close to the surface could cost as little as $1,000, or $25 per linear foot on average. Drains installed under your basement floor could cost $2,000 or more. Expect to pay $60 to $70 per linear foot for installation.

Should a French drain be covered with grass?

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.

How far should French drain be from foundation?

Recommended French Drain Installation Distance We recommend installing the french drains between 2 and 5 feet away from the foundation. There are a few variables that impact the exact distance to dig the new drain lines to carry water away from your home.

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.

How shallow can a French drain be?

DIGGING A TRENCH FOR A FRENCH DRAIN Because there is a direct relationship between the diameter of a drain pipe and its relative effectiveness, make your trench no smaller than 12 inches wide, and aim for a depth between 18 and 24 inches.

Does 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.