Information on installing a French Drain?

[BigguyZ]

Does anyone have any tips and/or a link to a good resource on making one?

When I got my roof redone and new gutters installed, they recommended that I run an underground pipe connected to the downspouts. I thought if I have to dig a trench for that, I might as well look into doing a French drain in addition to that.

Or, do you think I could use the same pipe as the gutter drain and the French drain?

Also, I'm wondering what kind of landscaping, if any can go on top of that... Currently it's just a bunch of weeds around my house perimeter, but I'd like to go for a clean look with just a slope away from the house, fabric to prevent weeds, and mulch. I hate planting/ gardening, so maybe a bush or two, that that's about it.

Thanks!

[gjat]

a French Drain and a Pipe are two different things. A Pipe, carries water away. A French Drain provides a place for the water to be re-absorbed into the ground. In other words, pipe is the road, a french drain is the destination. A french drain is basically like a drain field, excepet it's usually along a paved edge, such as a road way, ditch bottom, etc. It can be at grade, or below grade, depending on it's use and how the water travels to it. I would not recommend plantings on top, as the root systems would eventually clog and defeat the ability of water to slowly flow and be absorbed into the ground over a greater surface area.

[pelligrini]

In my experience a French drain is a drainage conveyance too, it can collect and move water. Quite often a perforated pipe is used to move the water quicker.

[gjat]

The preforated pipe works in concjunction with a french drain. The French drain is a gravel bed, seperated from the soil by a liner, minimally on the sides. Water will flow in a french drain, but it's not intended to travel far. That's why you see it at the edges of roadways. The principle is to provide greater surface area below grade to allow the water to perculate back into the ground. Using a french drain for a rain gutter is problematic because you have such great quantities of water that are concentrated into very small surface area.

Typically, imagine the gutters of a road being replaced by french drains along the whole length of road. Water flows in a sheet and enters the f-drain along it's length. Then picture having gutters, but every 200' having a collection box (inlet) for water then trying to get rid of the water in the collection box. It takes a hydralic engineer to calcuate the anticipated volume of water, factor the perculation rate of the type of drain, gravel, and soil condition to determine the needed surface area, then figure out how to re-distribute the water to the drain system evenly. The french figured out the common sense approach to provide adequate surface area along the road edge or building edge to eliminate moving or re-distributing water.

Then again, I'm picturing Florida t-storms where it's common to get 1"+ of rain in an hour for a few hours. That's alot of water.

[HarmsWay]

Here's a link:

http://www.ndspro.com/cms/files/POED_SC_2008_web.pdf

Do you currently have good soil drainage in the yard and good perimeter drains around the house? Then probably gutters connected to covered pipe feeding some kind of dry well or French drain away from the house is appropriate. If the perimeter drains are connected to a municipal storm water system then you may be allowed to connect the gutters also, however I'd recommend against connecting the gutters directly to the perimeter drain pipe (overloads and potentially floods the house).

For a new outbuilding, my municipality made me build separate dry wells for roof water and perimeter drains. My impression is that the recommendations around this sort of things are evolving rapidly.

Bob

[BigguyZ]

Thanks!

It's hard to go into detail, but my house is on a bit of a ledge, below which is the sidewalk. There's no additional drainage currently... But all I want to do is run the gutter drainage (and perhaps the French drain system) to the retaining wall that is along the sidewalk. So the additional water would draing over the sidewalk and into the street gutters.

[Uncle Cracker]

When you are installing a French drain, you can't shower afterward, and you have to surrender when the going gets tough...

[LCHIEN]

i thnk you'll get lots of assorted advice if you google French drain

[gjat]

Thanks!

It's hard to go into detail, but my house is on a bit of a ledge, below which is the sidewalk. There's no additional drainage currently... But all I want to do is run the gutter drainage (and perhaps the French drain system) to the retaining wall that is along the sidewalk. So the additional water would draing over the sidewalk and into the street gutters.

It depends upon your soil's perculation property and how far away a french drain is from the building. If the soil has lot's of clay, it won't allow the water to perculate back into the ground and the fines will easily clog the gravel. Also, do you have a basement? You may want to get the water as far away from your basement as possible. The third consideration, which I have no experience with here in Florida, is freeze. Could pooled water freeze in a french drain in a freeze/thaw cycle?

How about an exposed gravel bed for the water, like a dry river bed, for the water to spill into and guide toward the street? A bit of a ditch, lined with geo-textile fabric, filled with larger river rock, may look good, provide some percalation, and if it freezes, still alow water to run off.

[Thalermade]

How about an exposed gravel bed for the water, like a dry river bed, for the water to spill into and guide toward the street? A bit of a ditch, lined with geo-textile fabric, filled with larger river rock, may look good, provide some percalation, and if it freezes, still alow water to run off.

To solve a drainage problem at my Mom's house last year, I trenched about 130 foot long , 4 inches wides and 10 to 12 inches deep. Used a couple inches of gravel on the bottom, 4 inch perforated pipe and then another couple inches of gravel. Topped with several inches of dirt and planted grass seed. Had to cut the sidewalk to go under and the curb to get the pipe out to the street. The last ten foot was solid pipe. Tied in two downspouts along the side of the house as well. Mission accomplished.

For my yard, the idea of the "dry river bed" is one that was recommended to me by a landscaper and I am considering in trying it in my back ditch. Sometimes it can take 2 plus weeks to dry out enough to mow (and one of the neighbors has a yard sprinkler system which adds to it consistently as well).

On downspouts, the advice I was given was get the water away from the house, preferably 10 feet with solid pipe, then use the gravel/perf pipe method. Size of your roof, number of storms that dump considerable water and amount of yearly rainfall is something to consider as well.

I have read of people burying sump pump wells or large trashcans - filled with gravel and with holes poked in the bottom as a way to catch water and slowly drain it.

As mentioned before, there are plenty of solutions out there, but yours really needs to be tailored to your house and water situation.

sorry for rambling, but finally solving the drainage problem at Mom's house had made her a very happy person. She goes out in rainstorms to watch the water run out into the street, and not across her back porch.
Russ

[chrisk]

The Twin Cities area has a lot of sandy soils. I would recommend running the stormwater over the turf and see how things go. It will likely drain within your yard before reaching the street for most rain events.

Consider infiltration improvements if you have problems with standing water for considerable amounts of time. Rain gardens are becoming quite popular in the metro and are a great alternative if drainage problems occur. These can be low maintenance if done correctly. Plus you can reduce stormwater runoff, which is always good.

[gerti]

So the additional water would draing over the sidewalk and into the street gutters.

Doesn't sound like a good idea in MN... Could get dicy in wintery temperatures.