Installing a french drain...

Discussion in 'Community Discussion' started by fotografica, Apr 17, 2008.

  1. fotografica macrumors 68040

    Joined:
    Jan 7, 2006
    Location:
    Boston
    #1
    I'm going to install a french drain along the back of my house (approx. 50 lineal feet)..I'll be using perforated pipe as I'd like to bury my downspouts and tie them into the drain.It will be open ended and drain into a swale on the side of my house..Has anybody on here installed one? A couple of questions that come to mind right off the bat would be the slope for a 50' run,depth of trench and whether or not it's worth installing a cleanout? Just would like to know what I'm getting myself into first. Any and all information/input would be appreciated..Thanks...
     
  2. Plymouthbreezer macrumors 601

    Plymouthbreezer

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    #2
    Have you got any contractor estimates?? Sometimes, depending on the land, it might be worth it to have a professional do the work, assuming you can afford their labor (and expertise).
     
  3. ibook30 macrumors 6502a

    ibook30

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    #3
    Yeah- that's not bad advice, but if you choose to do it yourself, good on you. Make sure you get the right tools for the soil your digging into, a trench shovel,,, or if you wanna have some real fun, rent a trencher/ditch witch. That's probably overkill, but fun.

    Map it out clearly, and dig it. Maybe moisten the soil. Make sure gravity is on your side and the ditch is going down and not leveling/creating pools, or you'll be redoing the whole thing next year.

    Plan on spending more time than you expect, and get friends to help if possible! That's all I can think of!
     
  4. MacNut macrumors Core

    MacNut

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    CT
    #4
    Know where your utilities are, don't want to hit a gas or electric line. I think it is a do it yourself job if you have the proper supplies. Im sure Home Depot can help with advice....ok maybe not.

    You might be better off digging a dry well or a tank runoff to use for watering.
     
  5. lord patton macrumors 65816

    lord patton

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    Jun 6, 2005
    Location:
    Chicago
    #5
    at the very least, use a "sock" around the pipe. If you prefer to go the extra mile, surround the pipe with gravel, and surround the gravel with landscape fabric.
     
  6. iJesus macrumors 6502a

    iJesus

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    Location:
    Reno, Nevada
    #6
    That is the best advice so far.

    I recommend going the extra mile and doing what he said. It's better to pay more for something that will be worth it later on.

    My dad owns a landscaping business; I'll ask him in the morning.
     
  7. fotografica thread starter macrumors 68040

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    Boston
    #7
    Thanks for all the replies and advice. Yes,I've gotten three estimates so far and each is more than $2500. I'm quite handy when it comes to projects (built my own shed,put in a patio,built a grape arbor etc) and I don't mind doing the physical work. Trenching machine can be rented to dig,which is the hard part. My utilities are all in the front of my house (already checked). I'm thinking of a drain setup similar to the attatched picture. My idea is to let gravity,proper grading and landscape help with the runoff. And call in quite a few "owesies" from friends...Thanks again...
     

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  8. kjr39 macrumors 6502

    Joined:
    Nov 26, 2004
    #8
    I did this for a run of about 50' in my back yard. But, the trench I made was 12" wide (which is overkill.)

    - Rent a trencher from Home Depot. Works like a charm.
    - Call a stone company and have stone delivered in bulk instead of buying it by the bag.
    - If you can, leave the trench open at the top, it will work better.
    - The perforations do down.
    - Make sure to put 2-3" of stone down before you lay the pipe down.
    - I would put in a clean out (I didn't and am regretting it.)

    Mine cost about $500 total for the job and with two guys, two shovels, a wheel barrow, and a trencher, I was done in a day and a half.

    Well worth doing it yourself.
     
  9. fotografica thread starter macrumors 68040

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    Boston
    #9
    My thoughts exactly..If you don't mind me asking:
    What was your slope for the 50' run?
    How deep did you dig down?
    Thanks
     
  10. kjr39 macrumors 6502

    Joined:
    Nov 26, 2004
    #10
    I didn't worry about slope too much. There is a natural slope to the land that I dug in, so I just tried to follow that. (I did test to ensure that I would get good flow down the trench.

    And, I went 24" deep.

    It works like a charm.
     
  11. Ugg macrumors 68000

    Ugg

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    Location:
    Penryn
    #11
    I would definitely recommend the cleanout, especially if you have trees near your house. Leaves that get in the drainpipe can clog it in no time.

    Is the ground really soggy where you'll be running the drain? Is there a natural slope? If the main purpose is simply to remove water from the gutters, you may be better off with solid pipe.

    A pic would help!
     
  12. fotografica thread starter macrumors 68040

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    Boston
    #12
    Yes,the ground is graded along the foundation,off to the sides. There are swales that run along each side of my house. My problem is both runoff from the roof and a high water table in my area. I've attatched a picture. Water from the downspout in the foreground drains onto the patio and pools,heads strait down. I realize the patio has a negative grade toward the house..That will be graded and new pavers installed...
     

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  13. Ugg macrumors 68000

    Ugg

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    Penryn
    #13
    Perf pipe is probably best then, given the high water table. The ideal slope for water to drain effectively is 2% so 10 to 12 inches would work just fine for you.

    It's important that the bottom of the trench be relatively smooth. One relatively easy way to make sure that water will drain is to fill a garden hose with water and cap off the lower end. Lay it in the trench and remove the cap. After the water has drained, pick it up and see if any water is left in the hose. If the slope near the house isn't enough, the water could pool and make your problem worse depending upon the soil type.

    Make sure the pipe doesn't twist when you're back filling.
     
  14. fotografica thread starter macrumors 68040

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    Jan 7, 2006
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    Boston
    #14
    Thanks for your tips..Very helpful..We've had a very wet and rainy winter and spring here..I can't imagine the amount of water that comes off a roof when you get 2-3 inches of rain :confused: I'm guessing that by connecting some 4" PVC from the downspouts,it will prevent the perf pipe from twisting during backfilling..
     
  15. Ugg macrumors 68000

    Ugg

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    Penryn
    #15
    Another tip, make sure the swale can handle the volume of water coming from your drainspouts. Swales can fill quickly if the ground is saturated.

    Have fun!
     
  16. juliesjazz macrumors newbie

    Joined:
    Apr 26, 2008
    #16
    Can french drains do any damage?

    I've been reading the thread about french drains with some interest. I came home last night to find my neighbor ripping up our yard. I have to admit that not only am I annoyed that he didn't talk to me first, but I'm not sure he knows what he's doing.

    My backyard backs up to the side of his house. There is a swale where our property meets. He's pulled back the sod and dug a trench about 6 inches deep - in the swale - for the entire length of our property. His plan is fill the trench with gravel and a pipe that he has drilled holes into. Is this really going to keep water from coming into his basement? I'd add that his home is one of the few in my neighborhood that doesn't have a sump pump. I don't believe he's investigating that option at all.

    Thanks for listening!
     
  17. kant macrumors 6502

    Joined:
    Jul 22, 2004
    #17
    Some suggestions from watching a contractor put one around my father's house earlier this year.


    1: Do NOT use perforated pipe for the downspouts. Use solid pipe for those. You don't want the water leaching out the perforations one inch underground.

    2: Do NOT tie the downspouts into the perforated pipe. End them 6 or 8 inches above the perforated, so they spill out onto the gravel.

    3: Put a filter of some sort at the top of the downspout in the gutter. Don't want leaves, pine needles, etc going into the pipe and clogging the underground end. Which is also the reason for #2.

    4: Strong suggestion: made the trench a bit wider and put TWO perforated pipes in parallel. 4 or 6 inches apart. That way, 15 years from now, when one gets clogged or destroyed by a tree root or inhabited by gophers, the other one still does the job and you don't have to dig it all up.

    5: Don't end the pipe(s) out into the swale. End it 8 to 12 inches short and fill the rest with the clean gravel. Keeps critters from crawling up the pipe. Or mud, dirt, etc that builds up on top of snow (assuming that you get snow and it's deep enough to come level or above the end of your pipe.

    6: Supposedly a good 3 or 4 inches of hay on top of the gravel will not decompose and will keep the dirt from falling through and into the gravel.
     
  18. John.B macrumors 601

    John.B

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    #18
    PM sent.
     
  19. purrfektmoment macrumors newbie

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    Jul 25, 2008
    #19
    pvc underground to water garden

    We are about to lay pvc under my raised flower bed. It will be attached to the downspout with a 90 degree angle. The pvc will have holes so that the rain water will seep into the garden (underground) to keep the garden watered. It will be formed into a U shape approximately 14 x 8 x 14. Will it need a slope? Is there any thing I need to think about before doing this and will it work?
     
  20. Ugg macrumors 68000

    Ugg

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    Apr 7, 2003
    Location:
    Penryn
    #20
    If the volume of water flowing down the drainspout is more than the volume of pipe you lay, then the water will back up and either soak into the soil around the foundation (a bad thing) or make the gutters overflow and potentially allowing water to enter the house through the eaves (a very bad thing)

    By making a u, unless there's the proper slope, the water will simply stop at the bottom of the u. There needs to be a continual slope from the house to the very end of the pipe.

    There are a lot of variables. How much does it rain where you live? Will the volume of the pipe be sufficient for the volume of water? If your soil is heavy clay, the water will leave the pipe and enter the soil, very, very slowly. If it's sandy it will leave the pipe more quickly. What's the soil like? Does the ground slope away from the house? What if there's too much water, do you have some kind of overflow plan?

    Remember, water flows with gravity not against it. If the whole point of this exercise is to water the flower bed, then it might not do what you want it to do depending upon how deep the soil is, what kind of plants you have there, etc.

    A picture would help a lot.
     
  21. spork183 macrumors 6502a

    spork183

    Joined:
    Jul 30, 2006
    #21
    I have a huge french drain system that drains to a 12ftx12ftx12ft (yep, 12ft deep, you could have driven a truck into it) drain field since the county decided my rainwater from the gutters would contaminate the creek... Don't ask. Couple of quick things:

    1. My system sweeps directly off the roof into the pipes. There are cleanouts in the pipes, but it is a PITA. If you go that route, make sure you have good screens in your gutters, to avoid plugging up, especially if you have trees dropping crap on your roof.

    2. You need 1-2 inches gravel (lightly packed) and 1-2 inches drain rock below your pipe, Drainrock and a layer of ground cloth on top, under the dirt. This keeps dirt from filtering down as much. The bottom layer of gravel keeps some of the dirt from coming up when water is overly plentiful.

    3. You can do this one, piece of cake. In fact, when you're done, you can take the show on the road and do it for the neighbors at $2500 a pop.:D

    Best of luck, let us know how it turns out.
     
  22. Gray-Wolf macrumors 68030

    Gray-Wolf

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    Apr 19, 2008
    Location:
    Pandora, Home Tree
    #22
    A good french drain is about 1 foot deep, grade permitting, gravel under the pipe and over it, and yes, use perforated. It helps take the water that lies over the pipe and moves it away from that area.

    If your pipping water from gutters, then use solid pipe, but at the same time, gutter water would not be an issue to the surface if its piped away, eliminating a need for a french drain.
     
  23. purrfektmoment macrumors newbie

    Joined:
    Jul 25, 2008
    #23
    I hope this isn't the second post responding to your posts, because when I went to post.... it disappeared into Mac land somewhere never to be found I think.

    Anyways, Thanks so much for your quick replies. My friend just arrived and I ditched the project because, as you said, there are too many variables and scary possibility.

    To answer a few questions, we live in the Upper Peninsula of Michigan and we have some good downpours, more this summer than usual I believe. We will be removing the gutters before the snow falls (possibly as soon as October) :rolleyes: The pvc is 4" diameter, the downspout 3" diameter. The soil is very sandy below 2.5 ft of top soil and surrounded by an equal height of retaining wall stones. The flower bed is against the foundation which goes 8 ft below ground level. It does not slope away from the house, but it is instead a level 2.5 ft.

    Thanks for keeping me from doing something I may regret later. I still would like to find a way to use the rain water for the flower bed and for conservation. I will be using one of those expandable, rollup attachments in the interim to flow either into the garden or into the driveway. I may end up just going with a rain barrel which is my last choice. My friend said he would sell me his oak barrel for $150...I told him maybe if he put in a spigot;)

    I guess I'll be planting today, have a great day, cool forum, Lori
     
  24. fotografica thread starter macrumors 68040

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    Jan 7, 2006
    Location:
    Boston
    #24
    Since I started the thread,I thought that I would post a follow up..I went through and installed the drain system.I tied my downspouts into the drain using solid pipe,drain is perf pipe.I lined the trench with landscape fabric,put a layer of crushed stone under the pipe and on top of it. I dug down about one foot and followed the natural slope of my land. I'm just trying to eliminate surface water and pooling on my patio..One foot deep was enough..The pipe comes to daylight and empties into a swale that runs along the side of my house. We had a couple torrential rains the last couple days and it worked great..I couldn't believe the amount of water that was flowing out of it. Patio pavers will be replaced and the existing ones are temporary..Here are some pics.
     

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  25. Gray-Wolf macrumors 68030

    Gray-Wolf

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