Author Topic: DIY French Drain Install  (Read 1049 times)


  • 5 O'Clock Shadow
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DIY French Drain Install
« on: February 12, 2020, 12:26:58 PM »
Recently finished a massive project to install an interior french drain and sump pump. Others asked for my project break down in a diy discussion but I figured I'd post it here as well. Below is step by step for my interior french drain solution. I can not stress this enough this is a last line of defense option. You should try cleaning gutters and routing them away from the house as well as outside drain solutions before doing this. Anyways major project undertakers enjoy the breakdown below.

1. Determine lowest point in the basement. This is where you will need to place your new sump pump basin.
2. Map out your interior basement and determine where all drain lines will run as well as your exit strategy for water. I broke out one of my basement windows and sent the water out through there. I have 2.5 ft thick poured concrete walls in my basement (1922 was a crazy time). Note: check your local codes but I believe most states in the US do not allow you to pump it into your sewer line. The utilities don't want to clean the "clean" ground water again.
3. Figure out if you can generate enough pitch to flow water to your new sump. I used 1/8th inch slope per foot. To figure out the pitch space needed take the run length in ft of one proposed branch of drain pipe and multiply by 1/8 and 1/12. This will give u inches of top from start to finish needed. Add 6 inches for total in ground depth(atleast 3 inches of gravel and 3 inches of new concrete will go over the top of this drain pipe).  For example 100 feet of drain pipe away from sump would be (100x(1/8)x(1/12))+0.5=1.541 ft of depth. Some people will say this is overkill (which it may be) but its what i did and i had success. If you want to get real fancy you can factor in the pitch of your floor but to keep it simple I stayed out of that.
4. Try to find a sump pump basin that is 4 inches deeper than your depth. If you cant get anywhere near this than you may need to shorten drain line runs by adding an additional sump pump or move the sump to a more central location. 
5. Purchase basin kit, check valve, sump pump, and battery backup sump pump kit. Note: buy the best sump pump you can find especially if you have to pump vertically more than a few feet. I got a liberty aluminum pump (no rusting) with 1/2 hp, the thing is a beast. Also if ur ever going to put in a battery back up do it now. It only gets harder in the future.
6. Drill holes in sump basin. Make that thing look like swiss cheese. Seriously drill as many holes as possible without over weakening the basin to where it might crack. Also drill in holes for entry of drain lines. Attach a small run of drain line(I used 3 feet of 3 inch perforated corrugated black pipe) to each entry hole.
7.Plumb the sump pumps and backups so they are ready to drop in.
8. Execute your water exit strategy. Example drill your exterior wall to fit a 1.5 inch pvc pipe. Insert the pipe and run to desired area downhill from your home atleast 20 ft. Do not do any additional plumbing inside home. Just have it ready to connect to your sump pump once your sump pump is in.
9. Measure and chalk line off a square for sump basin area and at least the first 3 ft of the beginning of your drain line path. I would suggest making a square twice the diameter of your sump basin. Bigger is better though. The drain line path should be at least 1.5 ft wide. It depends on you footer though, and you will not be able to determine that until you start digging.
10. Cut floor with concrete saw and break concrete with hammer or jack hammer.
11. Remove concrete and dig out the square to a depth of the sump basin plus 6 inches. You will begin to see ground water during this. You have a couple strategies to deal with it. Bucket out the water, just power through the water being there, or temporarily set up sump pump basin and drop it in every so often to drain out excess water (super dirty water isn't great for your pump so make sure it is in the basin when u drop it in. This will prevent it from sucking up rocks.
12. Also make sure you dig out the beginning of your drain line path. You will want to find the bottom of your footer. You should see gravel when you get to it, if not dig another 3 inches deeper next to (not under) the footer and add gravel.
13. Once you have gotten to the target depth fill the sump basin area with 6 inches with clean gravel and drop in the sump basin. Fit the sump drain line entrance pipes in next to your footer. Cap the ends so they do not fill with gravel. place a thin heavy cement paver in the bottom of the basin to ensure it stays put while you back fill around it with gravel.
14. Drop in you plumbed sump and hook up to our water exit pipe. I believe doing all this first is best because if you have a true ground water problem all the trenches you dig will fill with water while digging making it a major pain in the ass. With the sump in place it with help to keep the water level down while you work on the rest of your project.
15. By now you should have determined where your footer is so you can establish a drain line path width. I would use atleast 1.5 feet as long as you have 7 inches of space from your footer(3 inches for drain pipe and 4 inches for clean gravel. Meaning if your footer extended in 11 inches from the wall you would need to have a total drain line path with of 18 inches. With this new dimension chalk out your drain line path and cut with a concrete saw preferable with a hose attachment to keep the dust down. Cut atleast 2 inches in depth. More is better as it will lower the risk for cracking when you are breaking it out.
16. Go back and now make a cut inside the drain path perpendicular to the path every 8 to 12 inches(making it look like sidewalk tiles). This will make breaking concrete in the specific place you want easier.
17. Break all concrete with jack hammer and haul out to concrete recycling area.
18. Dig all drain line trenches to the depth number you determined above plus 3 inches. You need atleast 3 inches of clean gravel under the drain line. This will be the longest step in the whole process. Just soldier though it there with be an end to the digging at some point.
19. Fill all trenches with 3 inches of clean gravel.
20. Start installing drain pipe. Wrap pipe in drain pipe cloth to prevent any solids from entering the pipe. Work back from sump pump to end of the line and add clean gravel to maintain the 1/8 inch slope per foot. You can also add clean outs at this point. I would put them at the corners. Just splice them in and measure correctly for height to the top of the trench.
21. With all pipe in place cover with clean gravel up to at least 3 inches below the floor line. If your basement floor is thicker than 3 inches match the thickness of your existing floor. Just ensure there is at least 3 inches of clean gravel above the drain pipe. This left over space is for the concrete.
22. Now soak all gravel with a ton of water. This will be a good test for your sump to make sure it all flows back to the basin as well as helping compact all the rock together. Also tamp the rocks down. Stomp and jump on them and all that stuff until they are completely compacted down. You dont want any settling to occur after you pour concrete.
23. If you have hollow basement walls or walls that weep at the joint between where the wall sits on the footer you will need to drill relief holes in the wall. For example if you have a cinder block wall you will need to drill a half inch hole in each block cavity to allow the water to drain.
24. Decision time: you can either then insert a small tube in each wall hole and caulk it in place so that it can drain into the clean gravel(make sure the end of the tube goes at least 2 inches into the clean gravel) or you can take dimpled foundation wall wrap and secure it to the wall above the holes. Then fold it into an L shape so it covers the holes and the entire drain line path.  This will allow the water to come through the wall and ride the wrap down to the gravel. It also will stop the concrete from leaking into your clean gravel and possibly your drain pipe (if you mix it too runny). I went with the foundation wrap and secured it using concrete anchors.
25. Seal the top of the foundation wrap with caulk. This will complete the water barrier and not allow water vapor to rise up and into your basement.
26. Now clean your basement floor get all dirt and dust up so you have a clean floor and clean existing concrete for the new concrete to bond to.
27. Calculate the amount of concrete needed and pour concrete in all spaces and level with existing floor. This is the part where you need all your friends. I had 4 yards of concrete to get downstairs into my basement. There was no other option than to bucket it by hand because all of my egress windows were too small and all the local concrete pump companies wanted $5000 to show up for the day. I ordered 4 yards from a local ready mix company and had them mix it on the dry side so set up time was fast but it would not be too runny and lose its shape while working with it. It is best to do this all at once or you will have cold seems all over your floor that could lead to additional water leak points. Also if you have to form concrete over the top of the foundation wrap on the wall. My blocks began above my floor so if I didn't concrete this it would have been exposed and more prone to breaking the caulk seal and leaking.
28. Ur done! The pain and worrying are over. Your basement should now be able to take on copious amounts of ground water.
29. Probably throw a party or something to thank your friends/family.

Project Stats:
Total basement size for reference: 1,000 sq ft
Midwest Basements quoted price $15,500 (included 3 total sump pumps)
My total cost: $2,345
Savings of $13,155!!!!!!!!!!! Which was amazing because I didnt have that much lying around since I had only just bought the house 4 months earlier.

Cost breakdown:
Sump Basin: ($50)
Sump Pump:($200)
Battery Back Up Sump: ($200)
Check valve:($25)
Gravel: ($450)
Concrete: ($700)
Jack Hammer Rental: ($300)
Drain pipe:($100)
Foundation Wrap:($150)
Caulk: ($50)
New basement window: ($80)
Concrete saw blades: ($20)
Sledge hammer: ($20)
Concrete tools, anchors, buckets, and shovels: ($0) already owned them
All My Friend Favors: (Priceless)

Post any questions. I'm sure people will have improvements and every situation is different so tweaks will need to be made here and there to fit your situation, but this is a good place to start.


  • Pencil Stache
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  • Posts: 564
Re: DIY French Drain Install
« Reply #1 on: February 12, 2020, 05:17:20 PM »
Are you going to check your Radon level now since the piping might allow more up into the basement?


  • 5 O'Clock Shadow
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  • Posts: 17
Re: DIY French Drain Install
« Reply #2 on: February 13, 2020, 08:20:36 AM »
I am going to seal the floor first with and epoxy first but yes after that i will