A French drain is a simple yet effective drainage system designed to collect and redirect excess groundwater. Named after Henry French, a 19th-century New England farmer, it consists of a perforated pipe laid in a gravel-filled trench, typically wrapped in filter fabric to prevent clogging. The trench should be about 18 inches deep and 9 to 12 inches wide, with a slope of at least 1% to ensure water flows down the pipe to its destination. For best results, slope down 6 feet for every 50 feet of pipe length.
The depth of the trench should be determined by your specific drainage needs and existing landscape conditions. A typical French drain system in a residential home has a four-inch diameter. The trench should be about 18 inches deep and 9 to 12 inches wide. French drains need a slope of at least 1% along the entire length of the pipe laid, which translates roughly to around.
For best results, don’t direct pipes to drain toward your home or onto a neighboring property. Obtain any French drink permits and ensure that the trench is at least 6-8 inches deep to protect it from erosion and digging. If your soil drains poorly (like heavy clay), a French drain might not work well without other changes.
To handle smaller drainage problems, use a trench that is 5 to 6 inches wide, while larger problems require a larger trench. Add the fabric and follow the instructions provided to build a French drain system. The proper build method is to excavate a 14″ wide trench, remove every shovel of dirt, haul away and replace it. A four-inch diameter perforated French drain pipe running five to ten feet is the standard size.
📹 How to Install a French Drain | The Home Depot
Follow these steps for installing a French drain in your yard: 0:00 How to Install a French Drain 0:17 Tools & Materials 0:27 Step 1: …
What does an exterior French drain look like?
A French Drain is a perforated pipe that collects and directs water from the ground, ensuring smooth drainage. It is covered with gravel or rock to prevent visibility and is angled downward for a smoother flow. This system is less open than open ditches and stormwater drains, but still allows water to drain to areas with less damage. It can also be used near retaining walls to prevent groundwell pressure from upheaving during intense rain. Installation is recommended by a lawn and garden professional.
Do you need to put gravel under a French drain?
The French drain is a crucial part of a home’s drainage system, allowing water to flow away from the home. The ideal gravel for a French drain is hard rocks like washed river rock or granite chips, with pieces ideally averaging at least 1 inch wide. If a perforated pipe is used, the gravel layer at the bottom of the trench should fill up about one-third of the way. If the arrangement does not contain a pipe, purchase larger gravel pieces with stones at least 1 1/2 inches in size and cover the trench with gravel until it’s two-thirds full. This layer acts as the main canal, preventing water accumulation in the yard.
Does an exterior French drain relieve hydrostatic pressure?
French drains are installed inside or outside homes to prevent hydrostatic pressure buildup by preventing soil saturation. They are buried along the foundation footer and channel excess water away from the foundation using gravity or a sump pump. French drains are different from channel drains, which are above ground drainage systems. Sump pumps, either submersible or pedestal, take water from the collection pit and pump it to the surface, away from the foundation.
Where not to put a French drain?
To prevent pooling in a French drain, it is essential to avoid the creation of low spots and dips, as these can lead to significant issues. The presence of moisture can attract tree roots, which can obstruct the flow of water and thereby reduce the efficacy of the drainage system. To obviate this phenomenon, it is recommended that a French drain exhibiting optimal drainage characteristics and free from any standing water, even in subterranean settings, be installed.
What is the minimum width for a French drain?
The best location for installing a French drain depends on the problem areas, nearby elevation, and soil condition. The best solution depends on your property’s unique features and the design tips provided by your installer.
To prepare for digging, consider city codes and consider how your new drainage solution will affect your neighbors. Contact the local utility company to mark any underground lines before digging. The drain depth should be between eight inches and two feet, depending on your needs and available options.
Measure the grading by pounding two stakes into the ground and tying a taut string between them for easy measurements. Dig a trench across the slope, with a width based on the size of the drainage problem. Smaller problems can be handled with a 5 to 6 inch wide trench, while larger problems require a larger trench.
Line the trench with landscape fabric and add additional gravel to prevent dirt from mixing with the gravel and promote water percolation. Place a slotted or perforated pipe at the bottom of the trench, directed towards an outlet to drain away from the home. Fill the trench with gravel, top it with another layer of landscape fabric, and cover it with topsoil and new sod.
In summary, seven easy steps for installing a French drain and eliminating drainage problems at your home include determining the best location, grading the trench, adding fabric, placing a pipe, filling the trench, and covering with topsoil and new sod.
How deep and wide to dig a French drain?
To guarantee optimal drainage, a trench measuring 18 inches in depth and 9 to 12 inches in width should be excavated from the point of connection between the drain and the outlet. During this process, it is essential to ascertain the presence of underground utility lines and pipes and to guarantee that French drains possess a minimum slope of 1 percent.
Can you put a French drain outside?
An exterior French drain is a system designed to collect and divert water from a building’s foundation, thereby preventing it from entering the basement or crawl space.
How far should a French drain be from the house?
A French drain should be installed 4 to 6 feet away from your foundation to prevent water accumulation. However, the distance may vary depending on the landscape and the severity of your water problem. Ensure the drain slopes away from your foundation to divert water properly. Improperly installed French drains can cause foundation problems by directing water towards your foundation, causing water seepage and potential damage.
A French drain must be deep enough to effectively divert water from your property, typically 18 to 24 inches. The precise depth depends on factors such as the severity of your drainage problem, property slope, and local building codes or regulations.
Which is better interior or exterior French drain?
An exterior French drain is less efficient in managing high water tables due to hydrostatic pressure exerted by water seeping from under the foundation. An interior French drain can handle hydrostatically percolating water and redirect rain runoff and local flooding, while an exterior drain is better at resolving rain runoff and local flooding. Interior French drains are less expensive due to avoiding excavation, landscaping, and obstacles like driveways or patios.
However, the choice between interior and exterior French drains often depends on the specific water problem being addressed. D-Bug Waterproofing can recommend the correct solution, as a French drain can significantly improve the lifespan of your home, protecting walls and basement from damage and ensuring dry, healthy, and safe living conditions.
Should I use a 3 or 4 inch pipe for a French drain?
The recommended size for a French drain installation is a 4-inch perforated pipe, according to industry standards and advice from authorities. This size ensures better drainage and reduces the risk of backups or clogs that may impair the drain’s long-term performance and effectiveness. A smaller 3-inch pipe is not recommended due to its numerous advantages. Universal Home Improvement, a leading French Drain Company, Contractor, and Installer, offers quality craftsmanship and 100% guarantee on all work.
One satisfied customer found Universal Home Improvement after experiencing water coming into their garage and basement during rain. The owner, Mark, provided a free estimate and assured the customer that he could stop the issue. The job took two weeks, including installing a new concrete walkway. Mark was great, came out daily, and the workers were friendly. The job was completed in two weeks, and the customer’s basement and garage are now dry. The customer has referred Mark to a friend who will also be satisfied with the French drain he installed.
What diameter should a French drain be?
French drain systems in residential homes typically have a four-inch diameter, but for areas with high water volume, six or eight-inch pipes may be suitable. PVC is a popular material for French drain piping due to its affordability and availability. Other options include ABS and corrugated plastic. Stratum Structural Systems, a local company specializing in waterproofing, foundation and exterior water issues, concrete leveling, and egress window repair, offers free consultations and can be contacted at 620-8153 or via contact form.
📹 How to Build a French Drain Full Tutorial in Less than 10 Minutes ( Veteran Contractor Explains )
In this video we’re going to cover how to build a french drain system we’re going to show you that not all drain systems are created …
Gotta say, if only all contractors were as honest and forthright as you. Lots of good “trade secrets” in this article but you’re helping homeowners get their moneys worth and best possible product and your also helping contractors do a better job through your experience and wisdom. It’s a win/win. Can’t thank you enough. Education like this usually comes at a high price and we are getting it here for free. Liked and subscribed!
Thank you for this! I have a drainage problem in my yard since its an old northern home with a narrow yard and a very hilly area. All the water pools at the back of my garage at the end of the yard. So sooner or later I need to install something similar. Since its a lot of tight spaces and only a few feet Im gonna diy since its probably too small a job for most contractors. Only issue is the best I can do is have the water drain out down a sidepath into the alley because of course there are no storm drains here.
I have a question. If I plan on using the 4″ high octane perforated for a curtain drain, and then want to connect it to 4″ corrugated solid to move the water far from my house where no curtain drainage is needed, would you use an inside or outside coupler to go from perforated to solid? Thanks! Your articles are great, BTW!!
There is alot of controversy over whether or not to use fabric covering the whole trench or just on top of the trench. The method in this article is saying use fabric in the whole trench. If no fabric then over time the rock will get clogged with dirt and no water will penetrate to enter the pipe. But the caveat to that is. When using the fabric. The fabric itself will get clogged with dirt over time. Then become impenetrable. So water won’t even enter the trench at all. Any thoughts on this?
Excellent article. I’m on 1 acre and have cows on 1/4 of it and in the winter they get ankle deep in mud so I want to put in a french drain and bought enough filter fabric for the entire 1/4 acre pen where I’ll put 1 1/2″ rock on all of it then on top of that pea gravel then on top of that I might put washed sand so the cows can lay on it. The french drain goes all the way around their pen area which is on a decent slope to the west. Do you have a suggestion for the pipe that exits the pen and continues downward to the west and I don’t have a storm drain to dump into, just a slight ditch that goes around the entire block (the ground just slopes down and then climbs back up to the road and is not cemented since we are rural)
Another great article. Just wanted to share that you have helped us install a french drain for a wall we just put in, tied to the storm sewer. Thank you very much from WNY. My only question is what kind of a slope do you guys usually go for over the run? It’s not like it’s moving solid way so I can’t imagine it would be that extreme.
We’re building an A-frame cabin in a high snow/rain area. Traditional gutters won’t work, as they’d likely be torn off by the snow sliding into/over them, and also the edge of the roof is close to the ground. We’ll be utilizing a french drain system, and I’m wondering if there’s a “norm” for how far out from the foundation the trench should be? Most of the house is roof (a-frame), so plenty of water coming off from it & I’m not sure if the velocity of the rain running off the steep roof makes a difference? Thoughts or advice?
Was the explanation for why water doesn’t just go back out through the perforations and into the soil is that it’s easier for the water to travel through the pipe than to exist through the geo Tex, so it takes the easier path? And that it likewise enters the geotex because that is easier to travel through than the dirt, thus also, taking the easier route…. Is this a correct understanding?
I really wish you were in my area. I’m in north Texas and I’m having a very difficult time finding a good company for this kind of work. At this point I’m thinking I might just buy the supplies from you and do it myself. Is a slope required? If so, how much? And if a pop-up emitter is being used to allow the water to come out, does the opposite end need to be higher than the pop-up emitter? I would think that without something like a sump pump the only thing that could push the water out where it needs to go would be gravity.
What if the only rocks that we can find are the round rocks of 1inch to 3 inches mixed in with a bunch of small pea gravel. They are not washed but that’s no problem because I can spray them with water to wash them. My main concern is the small size rocks that might plugged up the hole of the high-octane 8 slot pipe. So, what else can I do? Thank you.
Received my order on Friday, great products. For the 4″ catch basin kit with the pop-up door, the bottom doesn’t need to be capped? I’m guessing that just sits on the dirt without being capped? Description on the website “Sweeping 90° with open sump pit”. None of your articles show that level of install detail. I purchased the Downspout basin combo kit 4″ Corrugated
Thanks for this run through on drains. The thing is, most of the problems we are trying to solve with these drains are to save our homes and yard living spaces. I have a new home with a 4’x2′ open trench three website and a runout ( 400 to 500 ft total) dug because of water in the crawlspace. It’s huge and ugly at this point, but I couldn’t be happier seeing the storm surges run to the street in those trenches as opposed to knowing the under home was wet. Go Big, Do it once and right. Do it quick. Me, I’ll have open trenches for a few more weeks. Or until my orders come in. These products are just what I need to finish.
Hi. I see these “french drain ” green currugated slit openning pipes at Home Depot ( the french drains I’ve seen in the past are stiff white ones with circular holes all around and throughout}. It was put at the end of a downspout so it’s right at the foundation. It is long so it does route the water out further to a drain. Are these meant to be next to foundation above ground or further away to weap out the water further away from the foundation ? thx
I have a truly extreme drainage problem in my yard. I am essentially in the neighborhood’s catch basin as we speak. My back yard is lower than the front, everyone has developed around me, the front yard is flat and everything goes to one 30 inch municipal catch basin. I begged the city to stub me out an 8 inch pipe to connect to three feet down. That pipe gets completely overwhelmed. They’re coming to rip it out and give me a bigger basin with a bigger 12 inch stub out. I plan to run 220 feet of 8 inch and 300 of 6 inch to deal w the bulk water. Later down the line I will be installing French drains w this pipe. Wish I could get the 6 inch but the dual 4’s will do. Lord willing my yard will someday be dry. Do you think this is more than a homeowner can handle? Me too, but the clowns around here don’t seem to comprehend the extent of my problem or have the knowledge that I have about capacities and slope to do the job. I basically these guys to fly to Louisiana. My biggest question is whether my extreme leaf problem will clog 6 and 8 inch pipes on a .5% slope. My second question is how often within a very wet area I will need a French drain to make it reasonably dry. I have to put my bulk water basins in appropriate spots to later discharge the anticipated French drains. Any and all advice is wildly appreciated. Love the content, love the professionalism.
Love ur article. Came across another article from Apple Drains and damn I’d swear you 2 are a couple that broke up. He says not to ever do anything you do or use what you use. Almost literally everything. Your explanation makes more sense. But it’s funny he literally says don’t use an excavator, don’t use double punched fabric, just use any perf’d tubihg. I’m leaning towards your method’s because instead of sounding like a whining ex girlfriend, you actually justify with explanations as to why you do the things you do 👍🏻
Hello, I just had a french drain (open/closed) and downspouts routed to a 4″ PVC pipe, moving the water to a street sewer which my property has access to. This contractor used your products (wrap, 4″ high octane corrugated drain pipe, large gravel, 4″ PVC, and buttoned up the system like in your articles). Upon perusal this article, your comment about removing all of the dirt from the trench is a must as it shouldn’t be reused. In this case – the dirt from the trench was raked out beside the french drain along the side of the house. I’m asking this question as I went out this morning and walked the area beside the house and I have areas that are very saturated still. Should I be concerned? Thank you!
Question for you. btw I am also in Michigan. You probably already have a article on this but I have to ask. What do you do when you have no where to run the french drain? I would have to trench probably 200 feet or so and go through the utilities to get to the ditch by the road and the customer would rather not have that. So my customer takes all the water from her neighbors, and most of her yard is pitched towards the house. Can I run a french drain 20ft off the house and around the house into a NDS dry well with a catch basin on top? fill the hole with 6a stone and backfill with it as well. Thoughts? I just don’t know if you can use a dry well and french drain in unison?
How do I install my French drain system with a basement? Do I dig down to the footers install that pipe on the bottom up against the exterior of the wall fill it with 1 1/2″ rock and cover it like a burrito with the woven fabric and then fill the rest with the same rock all the way to the top? I also would put my downspout drains in a separate solid pipe on top of that and bring it all to daylight or do you have a better/different suggestion?? I am also going to waterproof the exterior of my basement wall any suggestions on how to do that??? Thank you. Your articles are awesome. West Virginia.
Hi robert, my name is Phil Albert, my brother Larry Albert purchased a French drain system from you, unfortunately my brother passed from cancer recently, if you want to article tape an installation it would be beneficial with your knowledge. I have many friends to help, unfortunately I only got my brothers concept, not his maser plan, any help you could offer would be greatly appreciated. Sincerely Phil Albert
Robert great article and will research where to get this high octane pipe as i am building a house this spring and have standing water issues on my lot. You did not speak about gravity feed on piping? Also can you tell me where i can get high octane piping and what i should expect what to pay and also is there a brand name for your non woven double punched geo fabric and where you buy it.
I am building a bunker in a below water table area, in an especially rainy climate. My solution to avoid flooding my bunker, is to build a French drain with entry ports on all 4 sides of the bunker leading back to a main pipe, that leads to the drainage ditch a few dozen feet outside my yard. Is this viable ?
my house has a slab but it is built into A 8 foot hill so the back of the house is covered by dirt. The front is free of anything. I’m gonna dig down to the footer and do exactly as your article shows on the back side. with a French drain along footer. But what would you backfill that With after you get the pipe in and the Stone and fabric all in line. What should I backfield that up to the 8 foot mark again???
I have an existing french drain system that dates back to when people didn’t know what they were doing. The PVC unfortunately runs underneath concrete (my back patio) to the back yard drain. The storm drain that sits in the concrete just doesnt cut it. Can I somehow cut the PVC where it starts in the yard, after the concrete ends, and fit it to one of these high octanes?
thanx. hvy rain here. we use 2’x 2’ trench, 3 1/2″ leach rock on pipes, 1 1/2″ on top. we usually leave top open. what did you use between top rock & sod: Filter/drain fabric or regular weed block? also, did you say that in some jurisdictions it’s code to put the French drain in the actual side yard setback?
I live in western Washington and need to divert rain/ground water from my upper pasture to my lower pasture where my home is(getting some basement flooding in the heaviest of rains. I wanted to build a sort of man made stream to look natural but in your opinion is this feasible? or a French drain better? it would be a couple hundred feet long.
Very informative article! just bought a house. need a french drain system to link all my gutter down spout drains to drain into the canal. House is 15 y/o. existing french drains probably chocked with roots, etc. Many questions on how to know where existing irrigation pipe is located; what is the plum angle for a long run of pipe;
Do you have to have the stone filling the trench all the way up close to the top of the soil level or can you put dirt in the trench? Say you last bit of pipe ends at 43″ down, do you have to fill the whole trench with stone or can you do like 6″ on top and then back fill with dirt so your not spending a ton on rock?
cool article I have a plot on a allotment that goes really flooded with rain water ther is a sump in place shower the warter level seems to have risen pat the draining out pipe would building a French Drain system to connect to the sump work I was thinking a few Chanel to connect to the man drains sump
Correct me if im wrong but your saying that simply putting gravel around the pipe will get stopped up quicker than the drainage fabric you use? I’m ignorant about this type of stuff but I have to say that doesn’t sound logical. The fabric your using is most likely had uniform holes or in it that are far smaller than the distances between the gravel and consistent in size making it more susceptible to getting stopped up especially when roots and weeds are thrown into the situation. Again I’m ignorant and just trying to figure out what I need to do to my occasional natural swimming pool that tends to magically pop into existence in my back yard after a good couple days rain.
I’m starting to get an education in yard drainage because the house I’m about to buy has some minor water infiltration issues in the basement. My goal is to make that 0 issues. Had two basement guys out who said all I needed was to fill the small cracks in the foundation. That made no sense to me, just a bandaid answer. What also doesn’t make sense to me, a lot of these guys use pond liner in the trench, so water can’t move in from the sides. Thanks for posting. Mark
You have not mentioned the rate of fall required per m/yd. Also – Hydraulic Cement not concrete as it says on the tub; concrete has aggregate in it – this doesn’t. If you are draining over a whole flat area rather than at the lowest point of a slope I don’t know how close the drains should be together.
Our builder installed an underground pipe in the alley between the houses to collect runoff water but 1) I do not think it has holes 2) there is no gravel or fabric surrounding it. It is just a pipe that runs underground connecting to several water basins that collect water in the alley. What problems will this type of faux French drain will cause? The alley is now mud and we have seen water puddles in a 1st floor room of our home but it has only happened twice (it doesn’t often rain where I live. They sent someone to extend the pipe to the street as it previously ended right before the sidewalk causing puddles on the sidewalk but I’m concerned the mud issue and future foundation problems might happen.