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.

What is the minimum slope for a French drain?

1 percent
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 deep should a French drain be around a foundation?

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.

What is the proper grade for drainage?

between 2 percent
Healthy drainage occurs when the slope is between 2 percent and 5 percent, which equates to 2 to 5 inches of drop-off for every 10 feet you measure as you move away from your home.

How shallow can a French drain be?

Add a Layer of Topsoil to Drainage Ditch The trench should be at least 2 feet wide, and can be as deep as 6 feet for a basement or as shallow as two feet for a slab-on-grade home.

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

Aside from what we’ve listed here, the difference between a French drain and a trench drain is that a French drain is used for water that is underground while a trench drain diverts excess water from a surface.

What size gravel is best for French drain?

1/2 inch to 1 inch
Gravel used for this layer is typically 1/2 inch to 1 inch across — the larger it is, the better the water flow and less chance of clogs and blockages. For a French drain without a perforated pipe, opt for even larger gravel, such as 1 1/2 inches across.

How do you dig a graded trench?

How to Dig a Sloped Trench

1. Place stakes in the ground at either end of the area where you would like a sloped trench and stretch string between them.
2. Cut the sod or the top 2 to 3 inches of soil away and fold it over next to where the trench will be.
3. Divide your trench into segments.