We have Bilco doors in our backyard that go down into our basement. Our basement is cinder block foundation. Unfortunately our entire back yard slopes downward toward the house, and so during heavy rainfall we end up with water pooling around the Bilco doors. This water seeps into the ground and eventually presses up against the outside of the cinder block foundation, and over time has damaged the cinder blocks enough to allow the water to weep through and start pooling in our basement:

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I believe a French drain system is the proper solution here, perhaps in conjunction with grace ice & water shield. Essentially I would trench out all the earth around the Bilco doors, going down several feet. I would slope the earth away from the Bilco doors and lay down grace ice and water shield. The bottom of the shielding would feed into a French drain (drain tile) that carries the water away from the house and into the back yard:

enter image description here

So rain water hits the Bilcos, slides of and onto the grass in front of the Bilcos. Seeps down into the ground, hits the ice shield, and follows along the top of the ice shield until it drips down into the French drain. From there is travels through the drain some 20 - 30 feet out into the back yard (the drain will be sloped slightly) until it falls into a big pit (that I will dig out and cover with grass) full of stone where it diffuses and spreads out.

I really think this will work. But one concern.

If the rain fall is heavy enough, I'm thinking it may still be very possible for the water that has seeped into the ground to still make its way underneath the drain and still find its way into my house:

enter image description here

So my question is: How far out should I be placing my drain so that this isn't a concern? Remember, the further out away from the house I go, the more rows of grace ice & water shield I will need to use, but that's OK as long as it works. Thanks in advance!

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    Would fix your landscaping first. Land should slope down from the house, not to it.
    – crip659
    Oct 17, 2021 at 22:42
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    Well this is like a $300 to $500 fix and fixing the slope of my backyard is like a $20,000 fix so I'll take "bug bucket of nope" for 500 alex Oct 17, 2021 at 23:47
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    You do know that you don't have to buy the backhoe. People with backhoe will come and do the job for you for about 50 to 100 an hour, one maybe two days work.
    – crip659
    Oct 18, 2021 at 0:00
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    In reality this is happening all the way around two sides of my house, not just around the bilco doors, the bilcos is just where its the worst. So yeah, bring in a crew to excavate all the earth away from 2 sides of my home, parge the exterior wall, install a drain, fill and tamper it back down...not gonna be just a few thousand. Oct 18, 2021 at 0:19
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    Are you on storm/sewer from a city? Does the water table level ever get above your footings? Do you have a sump in the basement to gather water, does the sump have a pump? Oct 18, 2021 at 4:21

2 Answers 2


French drain below foundation level, problem solved. Anything less than that, problem potentially remains.

And crip659 s also correct - you should fix the grade - my rule of thumb is that you want at least 12 feet around the house to slope away from the house by at least 1%, 2% better. i.e. the part 12 feet from the house should be 1-1/2" to 3" (or more is fine) lower than the grade at the house.

Either way, or both, some major landscaping.

  • Is your rule of thumb based on anything citable? Oct 17, 2021 at 23:52
  • The fact that water runs downhill suggests that Ecnerwal and Crip are thinking right....
    – gnicko
    Oct 18, 2021 at 2:19
  • Have you thought about linear drains in front of the Bilco doors plus all of the regrading and waterproofing?
    – DAS
    Oct 18, 2021 at 2:35
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    @GregNickoloff you can elipses all you want but I'm obviously not asking for citation on gravity; I'm asking for citation on this 12' and 1% slope rule. Oy vey... Oct 18, 2021 at 9:47
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    My direct-to-thumb route is personal contact with a civil engineer for a long time and many projects. But as with most well-honed things, sure, there are cites if you want cites. The slopes and distances suggested vary. mmsd.com/what-you-can-do/managing-water-on-your-property/… This is half what my thumb says: basc.pnnl.gov/resource-guides/… and this is 2.5 times that: thespruce.com/…
    – Ecnerwal
    Oct 18, 2021 at 14:08

Update at the 24-month mark:

Well, I followed this solution and have taken in no water whatsoever for 24 months now. Bone dry! If it can work for me I think it is a good emergency solution for n e 1.

Since this is Do It Yourself SE and not How to Hire A Contractor SE here is the trigonometry-based solution I'm going with, based on an assumption that rain water, once it hits the ground, will not "wick" or seep at a slant greater than 45°. I base this on a question I found off of Physics SE. It may not hold true in extreme case such as if we have a persistent torrential downpour for many hours, without relent. But if that only happens once or twice a year, I can live with this as the "permanent, temp solution".

My foundation goes down 7'. If I draw a right triangle we will see that a 45° angle is formed 7' away from my bilco doors. This means that rain water hitting the ground 7' away from my bilcos should almost never wick/slant all the way to my basement:

enter image description here

So then, all I have to do is provide grace ice and water shield all the way down from the right angle to the hypotenuse, and place the drain on the hypotenuse, which is 3.5' out and 3.5' down.

  • 2
    Minor nitpick: This is actually "Home Improvement SE", but "homeimprovement.stackexchange.com" could be fairly hard to type correctly on the first try. There's plenty of "DIY" topics that are off-topic here, and plenty of not-strictly-DIY questions that are welcome. :-)
    – TooTea
    Oct 18, 2021 at 11:24
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    One of your comments said: “In reality, this is happening all the way around two sides of my house, not just around the bilco doors.” Are you sure you aren’t dealing with saturated ground water rather than just runoff? If so, this solution is like slurping all the soup out of the middle of the bowl and expecting no soup to be left at the bottom. This is why most french drain systems are installed at the footer of the home. Oct 18, 2021 at 11:29
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    You said in the original question that "...our entire back yard slopes downward toward the house...." How do you suppose a French drain is going to reverse that?
    – gnicko
    Oct 18, 2021 at 13:22
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    You can rent equipment, if DIY is a core tenet for you. It may or may not be cost efficient to do so - the cost of learning how to use the equipment can be low or very high, as mistakes can be very expensive indeed. The time required will generally be longer than if done by an experienced operator, but if you are careful and up to learn how, it's certainly an option. How water moves in the soil depends a lot on what the soil is - sandy/gravelly material is very different than clay (and wet basements are rarely a problem in sandy soil, unless the water table is high.)
    – Ecnerwal
    Oct 18, 2021 at 14:16
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    Updates belong in your post, if anywhere, not down here in comments.
    – isherwood
    Apr 11, 2022 at 15:12

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