Shop Products
Houzz Logo Print
vandyalum02

French Drain or Regrade or Both?

vandyalum02
9 years ago

Good morning. I am purchasing a house and due to water leaking into one sideof the cellar during hard rains, the owner agreed to install a french drain and/or regrade around that side of the property. Yesterday, the contractor installed the french drain. You can see where it was installed per the photo. My soon-to-be house is on the left.

Here are my questions:

(1) As you can see, the houses are closely set together. Though the contractor installed the french drain, he did not regrade. Given the amount of land available and the height of the foundation wall, is it possible for him to regrade?

(2) Even if possible, given the existence of the drain, is regrading necessary?

(3) Separately, as you can see from the photo it appears that he connected the downspout to the drainage system. Is this advisable?

Thank you.

Comments (10)

  • PRO
    Yardvaark
    9 years ago
    last modified: 9 years ago

    Describe what a "french drain" is. What do you now have? I'm sure it is a "joke" to help sell a house.

    The surface grading obviously drains all the water toward your house. Only surface re-grading can fix this. there should be a swale running the length of the center of this space. But it's such a tight space a curb and elevation change would be useful. And a hard paved gutter would be useful. The water would drain toward the photographer and beyond, but we can't see that so wouldn't know if anything terrible is going to happen with water as it leaves the two houses.

  • vandyalum02
    Original Author
    9 years ago
    last modified: 9 years ago

    What was installed is a french drain, aka a perimeter drain. Basically, the contractor dug a trench along the perimeter of the house, presumably laid down gravel, put in a perforated pipe, laid down more gravel on top, filled it back with dirt.

    Here's the problem with the swale. It would certainly need to encompass a portion of the property that is arguably not mine. And I think to do it properly, earth would need to be removed from the neighbor's property, and I'm not certain the adjacent land owner is keen to have this done. Nonetheless, the photographer (me) is standing at the sidewalk. Nothing terrible will happen with water as it leaves.

    Can you explain further what you mean by a curb and elevation change? I presume you would put the paved gutter in the swale, or somewhere else?

    Thanks!

    This post was edited by vandyalum on Wed, Jul 9, 14 at 22:34

  • pls8xx
    9 years ago
    last modified: 9 years ago

    You mention two terms, french drain and perimeter drain. A house perimeter drain is built at a level below the basement floor elevation. In your case this would be about 8 feet deep. A proper and working perimeter drain keeps the water table outside the foundation walls below the basement floor level. This prevents excessive hydrological pressure on the foundation wall and deters water leaks into the basement.

    A shallow french drain can de-water some soil types above the bottom level of the pipe. But the soil below that level usually is wetter than without the drain. Such drains along foundation walls often lead to water problems in basements or make existing problems worse.

  • vandyalum02
    Original Author
    9 years ago
    last modified: 9 years ago

    Ok, nomenclature aside, the contractor installed what I described above. If a perimeter drain is technically what you describe, then I'm certain that wasn't installed since, I don't have a basement. I have a crawlspace in the front and back of the house and a 10x15 cellar in the middle.

    What I really need to know is (1)-(3) in the original post. After the owner (who, by the way, is a contractor) suggested that he would install a french drain (and arguably regrade), I had a a few contractors come out to look at the house, and they all independently suggested a french drain. I'm not saying that they are all right, and perhaps the answer is not a french drain, but for the time being, the french drain - or whatever you want to call it - is installed.

  • pls8xx
    9 years ago
    last modified: 9 years ago

    (1) As you can see, the houses are closely set together. Though the contractor installed the french drain, he did not regrade. Given the amount of land available and the height of the foundation wall, is it possible for him to regrade?

    Yes (see Yardvaark's suggestions). IMO, the french drain should be removed before regrading and all near surface backfill used in the area should have low permeability. This may not solve the water problem in the cellar but is the first step before much more expensive things are done.

    (2) Even if possible, given the existence of the drain, is regrading necessary?

    Yes.

    (3) Separately, as you can see from the photo it appears that he connected the downspout to the drainage system. Is this advisable?

    No. Roof drains should not be connected to subsurface drains. Roof water should be routed through solid, not perforated pipe, to a suitable discharge point.

  • allen456
    9 years ago
    last modified: 9 years ago

    Where is the gas line that serves that meter in the back?

    If you're going to do any digging, make sure you locate the utilities.

  • vandyalum02
    Original Author
    9 years ago
    last modified: 9 years ago

    A quick follow-up for clarification:

    The french drain in and of itself has failed, given that after hard rains last night the cellar leaks as it did before the drain was installed. Whether it failed because it was not properly installed or because of the grading is unknown, though it's likely the grading or a combo of both. In any event, regrading is essential.

    PLS8XX, you suggested that the drain needs to be removed before regrading. Can you explain why? Is it not possible to leave the drain in and regrade on top of it? I'm just trying to arm myself with information.

    Thanks!!!

  • pls8xx
    9 years ago
    last modified: 9 years ago

    I suggested the removal of the french drain because it's common for the soil above a french drain to be dryer, but the soil below the drain pipe is often wetter, which is not good along a basement.

    You may very well get by with leaving the drain in place if all of the surface soil in the area is of low permeability. It will help if part of the area is covered with a concrete gutter as suggested by yardvaark. Make sure you disconnect the drain from the pipe carrying the roof water.

  • vandyalum02
    Original Author
    9 years ago
    last modified: 9 years ago

    All the suggestions on here have been so helpful.

    One final (hopefully) question. The drain does not work. Meaning, there is no water flowing out of it. After the first rain, I had a suspicion this might be the case, but I didn't know for sure. After a few dry days, I tested the drain by flooding the area. Water leaked into the cellar. No water flowed out of the end of the drain.

    Presuming the drain was properly installed, are there any other reasons? Perhaps the water is disappating into the soil too quicly?