what is a french drain and how does it work

A French Drain is a pipe that collects and directs water. A wide, perforated pipe placed in the ground collects excess water and drains it away from the affected area. The pipe is covered with gravel or rock so that it's not visible, and it's angled downward to make sure drainage is smooth.

1. When should you use a French drain?
2. What is the point of a French drain?
3. How do you know where to put a French drain?
4. Are French drains effective?
5. Do holes go up or down in a French drain?
6. What is the difference between a French drain and a trench drain?
7. How far should a French drain be from the house?
8. Do French drains need to be sloped?
9. How long do French drains last?
10. Can you cover a French drain with dirt?
11. What size gravel do you use for a French drain?
12. How much is French drain installation?
13. Why do French drains fail?
14. What is better than a French drain?
15. Do French drains need maintenance?
16. How do I dig a French drain around my house?
17. Can you drive over a French drain?
18. Should I use PVC or corrugated pipe for drainage?
19. How do I divert water in my yard?

When should you use a French drain?

French Drains are primarily used to drain groundwater from gardens and around the foundations of buildings. French drains are designed to move water that is trapped in the ground away or towards an area. They are best used in soil that is prone to frequent saturation from rain or flooding.

What is the point of a French drain?

A French drain is a gravel-filled trench that includes a perforated or slotted pipe. It is used to direct surface water or groundwater away from a specific area, such as a home's foundation.

How do you know where to put a French drain?

French Drain Installation

1. Determine the best location. Determining the best location depends on where the problem areas are located, nearby elevation, and the condition of the soil. ...
2. Prepare to dig the French drain. ...
3. Measure the grading. ...
4. Dig a trench across the slope. ...
5. Add the fabric. ...
6. Add pipe. ...
7. Fill with gravel.

Are French drains effective?

French drain systems are incredibly effective because, unlike typical surface drains, they collect water over the entire length of the drain as opposed to one dedicated area. The force of gravity helps to guide water along a reliably smooth path to a desired discharge point.

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.

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 far should a French drain be from the house?

How Close Should a French Drain be to the House? A good rule of thumb is to install french drains 3 feet from the house.

Do French drains 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.

How long do French drains last?

How long do french drains last? Properly installed drains use advanced plastic sheeting called geotextile to protect the drainpipe from a blockage. French drains can last decades before needing maintenance. If your home requires a sump pump, a high-quality model will last around ten years before needing replacement.

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. ... The drain can be left open or, if aesthetics are a concern, can be covered with a couple of inches of topsoil and sod.

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.

How much is French drain installation?

An exterior French drain is only installed two to three feet deep to help move the water away from your property, making it less labor-intensive to install, costing about $10-$15 per linear foot for parts and labor with an average cost for installation around $1,000 to $1,500.

Why do French drains fail?

This issue could be due to clogging. When water seeps through soil to get to the French drain, it often brings along sediment into the drain, where it dumps the sediment in the drain on the gravel as it flows through the ditch.

What is better than a French drain?

If you have a negative sloped yard (which slopes toward your foundation), a surface drainage system is a better choice than a French drain. Sloping of more than 1”-1-1/2” on a 10' run can result in excessive amounts of water seeping beneath your house.

Do French drains need maintenance?

French drains need annual maintenance

Despite the design's best efforts, French drains get clogged by dirt, debris and silt. They do need to be cleaned out regularly – about once per year – to ensure that they continue to direct water away from the building's foundation.

How do I dig a French drain around my house?

How to Install a French Drain

1. Call the 811 hotline to have underground utilities marked.
2. Dig the trench system.
3. Line the trench with landscape fabric. ...
4. Add 2 to 3 inches of gravel to the bottom of the trench.
5. Lay the drain pipe in the trench, with the drain holes facing down.

Can you drive over a French drain?

A true French drain is made with gravel, but with gravel driveways, PVC piping is recommended. The PVC piping only needs to be 4 to 6 inches in diameter for draining purposes. It must also be rugged enough to withstand the weight of vehicles driving over it.

Should I use PVC or corrugated pipe for drainage?

So, for preventing clogs and keeping your drain water flowing long term, pvc is the winner over corrugated pipe.

How do I divert water in my yard?

shovels

1. Dig a Swale. A swale is a shallow trench that redirects water to where it can be safely released. ...
2. Construct a Dry Stream. Like swales, dry streams redirect water and prevent runoff damage. ...
3. Grow A Rain Garden. ...
4. Build a Berm. ...
5. Route Water Into a Dry Well. ...
6. Lay Pervious Paving.