french drain calculator

1. How do you calculate the size of a French drain?
2. How deep and wide should a French drain be?
3. How much gravel do I need for a 100 foot French drain?
4. How much should a French drain cost?
5. What size gravel is best for French drain?
6. Do holes go up or down in a French drain?
7. What is the difference between a French drain and a trench drain?
8. How long will a French drain last?
9. How far away from the house should a French drain be?
10. What is the best fabric to use for a French drain?
11. Can you install a French drain without gravel?
12. How many inches of gravel do I need for a French drain?
13. Is a French drain worth it?
14. Does a French drain add value?
15. Which is better interior or exterior French drain?
16. Can I use river rock for French drain?
17. Is it OK to put gravel next to House?
18. Do I need a catch basin for French drain?
19. Why do holes go down on French drain?
20. Can you cover a French drain with dirt?
21. Will a French drain work in clay soil?

How do you calculate the size of a French drain?

How to Calculate Gravel for French Drains

1. Measure the trench, in feet, noting its length, width and depth. ...
2. Calculate the sum of the width measurements and divide by the number of measurements taken to calculate the average width. ...
3. Calculate the average depth using the method described in Step 2. ...
4. Measure the diameter of the drainage pipe.

How deep and wide should a 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.

How much gravel do I need for a 100 foot 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.

How much should a French drain cost?

French drains, for example, average $20 to $30 per linear foot or between $1,000 and $1,500 in exterior applications and $45 to $60 per linear foot or $5,000 to $6,000 for internal ones. These systems can benefit your home in a variety of ways.

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.

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 long will a French drain 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.

How far away from the house should a French drain be?

To get the correct distance to put in a French drain is 3 feet distant from the house, usually most homes. Apply to measure with tape and find the distance from the bottom of the ground where water pools. If space is too off from the base, the French drain will not gather the entire water.

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

Quality 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.

Can you install a French drain without gravel?

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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.

How many inches of gravel do I need 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.

Is a French drain worth it?

If you're dealing with a wet basement or a soggy lawn, you might want to look into installing a French drain. While it's not necessarily a “quick fix,” a French drain can be a smart investment to keep your home and yard dry.

Does a French drain add value?

French drains remove the water before it has the chance to enter the basement, cutting back significantly on water damage and flooding that might have otherwise occurred. ... French drains can also add value to your home, which is a huge bonus if you know you are planning to put it on the market in the future.

Which is better interior or exterior French drain?

Conclusion. Both exterior and interior French drains provide effective protection against flooding and water damage in your basement. Yet, due to the costs and difficulty of installing and servicing an exterior drain on existing houses, it may be better to install interior drains.

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 it OK to put gravel next to House?

Placing organic mulch or inorganic ground cover such as gravel around foundation diminishes weed growth and helps to make a building look tidy and well-maintained. ... Gravel beds around a foundation are safe as long as they do not impede water drainage or keep the adjacent soil too moist, which encourages termites.

Do I need a catch basin for French drain?

The drain itself is an NDS 12-inch catch basin. I strongly recommend this over a drain grate unless your french drain is being fed by a downspout. By connecting your pipe to the catch basin, you're allowing water to flow into your drain without the silt or any other muck that might enter the grate.

Why do holes go down on French drain?

A review of installation instructions from several State DOT manuals reveals that the holes should be down (i.e. placed facing the bottom of the trench). The reason is that this allows the water to enter the pipe and drain from the soil at the lowest level.

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.

Will a French drain work in clay soil?

The clay soils have less to do with clogging the french drain, and more to do with the water not being able to penetrate them. The permeability of clay soils is very low when compared to that of sand and other granular soils. If you have clay, they will not drain properly.