Linear French Drain Illustration
Summary: Here is a diagram for installing French drain systems around your home. The linear French drain design is simple. The slope of the soil around the home is very important to keep in mind.
Related Terms: French drains, French drain design, trench drain
! ! ! See Author's Notes at Bottom of Column ! ! !
Author's Notes:
You may wonder if my advice is worth anything. Well, read what Jim Sanders wrote to me when he was at the end of his rope:
"Hi, I just wanted to write to give you the results of my "Trench Drain". I have had a wet crawlspace for 15 years. Water would fill the crawlspace at times, so we actually had to drill weepholes at the base so that it would enter the basement and eventually, the sump pump.
I have tried everything. Several contractors said that the only thing we could do was to bring the water into the house via drainage tile and let it enter the sump pump. That would work, but because I live on a 6' elevation, there is no reason that I should have water problems. It became like clockwork...when it rained, we would rush home from the lake or wherever we were vacationing so that we could be prepared to start the backup generator, in case the power failed. We even had our alarm company put a sump alarm on our system, so they could notify us if we had a power failure. Battery backup was not an option, because sometimes we loose power for days and during any rain, our sump would run every 7 minutes...just like clockwork.
I found your site and read the article on the trench or French drain. At first, it sounded a bit like "holistic healing" to me. I failed to understand why a 2 ft. deep trench, 4 ft. away from the house would do any good. How could this simple thing correct an extreme water problem that has plagued me for years, cracked my foundation, settled my garage floor and ruined almost every vacation?
I stoned it, put tile in, and filled it with #1 round stone. I socked the pipe just for safety measure and I also used geotext fabric on top, so I could cover with dirt and grass. I also ordered some clay and pitched from the house to the drain.
Since I couldn’t see correcting the foundation cracks or the garage floor settling and tilting until I corrected the problem's source, I waited to see if the trench drain worked first.
This week, I had a company come in and perform sort of a "mud-jacking" technique on the garage floor, which worked perfectly. Also, during the past few weeks, I parged the cracks in the foundation.
As a side note, I went to the end of the drain tile during a hard rain to see what was happening. Water was running out of the drain tile in about the same exact volume that it previously ran out of the weepholes in my crawlspace. This winter will be interesting, because last year, the ground next to the house was so saturated that during a thaw, my sump would run constantly. I'm guessing that the ground between the trench and the house will probably be drier now going into this winter."
- Jim Sanders, Upstate area - New York
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Comments:
Ruben Loioco 27 Nov 2007, 13:18
I represent my client in buying this house with drainage problem in Los
Angeles and I need to have an expert to answer few questions for me and my
client, can you address me to someone to give us an estimate to resolve
this problem please 310-642-7653 xt 128
Ruben
Jeffrey Ogno 04 May 2008, 13:34
My modular home sits on a full poured concrete basement. The 5 acre site is
all bank run gravel. There is a stream 175 feet from the back of the house.
Two summers ago we had very bad rain, and the stream level was very high. That next morning our basement floor heaved up and split from one end to the other, allowing 5 feet of water to enter the basement. There was only puddles on the ground outside, this water came from under the home. The stream never overflowed. What kind of drainage can you recommend to overkill this problem and ensure it never happens again? Thank you Jeff
danny 19 May 2008, 16:37
When installing a french drain should the holes in the pipe be up or down.
I have heard both ways.
Roger 20 May 2008, 09:00
Danny,
In Tim's column - http://www.askthebuilder.com/B175_Soil_Drainage_Solution_French_Drain_Syste ms.shtml - he states that the holes must be down. Check out the column for his reasoning.
Ruhi 01 Jun 2008, 11:08
How far the french drain should be positioned from the foundation walls?
Would be OK to have it away, say 10-12 from the foundation as long as there
is enough slope away from the house towards to drain? Thanks.
jayamohan 15 Dec 2008, 08:10
List of Manufacturers of french drain pipes
Brian 20 Jan 2009, 22:47
Please Help. I have a water problem on the side of my house and getting
into my crawl. So I have started the french drain process.
I have it all dug out and started filling with rock, but I have really struggling getting grade with the rock. I want to be at grade before I put the 4" pipe into the ground. My trench is 80'. I started at the deapest end and worked back to the shallow side, but by doing that, I am having to add a few inches of gravel, which makes me worry the pipe will no longer be deap enough at the front. The deapest part is in the back, which is also the side that goes downhill. Can you help me with any grading advice and where I should start and if I should grade the ground, the rock, the pipe or both or all. Please help. Thanks.
Cynthia Warren 24 Mar 2009, 05:52
Hi, I have read the article on the linear french drain and I think it would
work for me. I do have one problem though. On the back of my house (where
the water is coming in the basement) I have a deck that extends 10 feet.
Can I gradually run the trench around it or do I have to remove the deck
for this solution to work properly? Please advise.
Scott M 17 Aug 2009, 11:12
Hello. Your drainage articles have been very helpful. However, I am still
uncertain about one point.
I live in NH and have a landscape grade similar to your French Drain Illustration with the the slope hitting the house mostly from one side. The 4-6 foot distance from the foundation you recommend makes sense here. However, I think I might have even more trouble from the room runoff which drips close to the foundation walls and in heavier rain enters through the rubble wall in the garage. The top of our foundation unfortunately is only about 6" above grade so I don't see much I can do about regrading to get a better slope away from the house. We have no gutters--and with a giant oak above our house, I'm not sure that is a great option. My inclination is to have the trench capture some of the roof's dripline (8" from foundation in older section of house & 20" in new section), however you have strongly recommended 4-6 feet away. Any suggestions to also pull the roof runoff away? Thank you. Scott
derek 22 Sep 2009, 15:10
my situation is kind of the opposite of this illustration. my back yard
slopes away from my house to the far end of my yard. the problem is that
when it rains my yard floods and resembles a lake. any suggestions?
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