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Water in CrawlSpace

Joe Norm | Posted in General Questions on

I went to great lengths to get the footing drains correctly placed around my perimeter foundation(working with an experienced excavation contractor) but with even the first rains of the season I’m getting water under the footers and into the crawl on the wet(uphill) side of the building.

One problem is that I do not have gutters on the building yet, and its a shed roof emptying to that same problem side of building. I am doing my best to manage this bulk water with tarps before I get gutters installed but inevitably some is making its way near the foundation.

My question is why the footing drain is not doing its job? It was laid right at the bottom of the footer on level ground with holes down. I did lift the pipe just very slightly on the up hill side of building to give the pipe a very slight pitch toward daylight, so it might be 1-2 inches above the very bottom of the footer in the problem location. I’m wondering if this is enough to allow water to flow underneath the drain? my understanding when I installed it was that water would hit the footer and rise until it reaching the drain, then be taken to daylight. I can clearly see that is not working.

One thing the excavation contractor did that I question is leave a lot of gravel fill exposed all the way to the top. So its essentially acting like a big rain catch, it does not have the impermeable “cap” of clay I see in the diagrams.

I think the next course of action may be to dig a primary curtain drain ditch on the wet side of the building to take bulk water away before it gets to the foundation. I would dig this trench just a bit deeper than the bottom of the footer. Soils are of high clay content.

I am pretty surprised after all the work and planning that the drain is working so poorly.

Thoughts?

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Replies

  1. Expert Member
    Peter Engle | | #1

    Joe,
    Your post raises several issues:

    1. You mention that the water is running under the footings and into your crawl space. This suggests that the crawl space floor is at the level of the footings? If so, do you plan to leave it this way? That would be a bad idea. The whole point of placing the drains alongside the footings is to drain water from below floor level. If you look at any of the various details they will show the floor slab resting on top of the footings, with the top of the drain below the bottom of the slab. If your floor is below your drains, that would be a problem.

    2. You have already diagnosed 3 parts of your problem:
    2a. You have a shed roof dumping water on the uphill side of your building.
    2b. You have no gutters. Install gutters with runoff drains that carry water around your building, ideally depositing it away from the building and downhill.
    2c. You have gravel running up to the surface where a. and b. are happening without any impervious cap. Install the cap.
    2d. You have high clay content soils. This could be a good thing because you have a local source of clay to fix #2c.

    The next course of action should be to fix everything in #2. Those are your permanent fixes anyhow. Do all of that before considering any sort of curtain drain. It sounds like your problem is roof water. A curtain drain is not going to help that a bit.

    1. Joe Norm | | #4

      Thank you.

      The floor level issue is news to me. It’s going to be a dirt floor with a well detailed poly battier. Does that mean I should have filled the whole interior of the crawl with fill up to the footer? It is certainly not done like that around here, hence my excavation guy not even suggesting it. The reasoning makes sense. Unfortunately to do that now would be a brutal amount of work.

      The reason I suspect I may need a curtain drain is there is also a lot of uphill water flowing as well.

      I’ll fix the gutter problem and the open gravel soon. But I do suspect a curtain drain might help deal with some of the surface water. If it was dug slightly deeper than the footer it may actually be an easier fix than adding fill to the crawl.

      1. Expert Member
        Malcolm Taylor | | #7

        Fill the crawlspace floor up to and several inches above the footings, put down poly and pour a concrete scratch coat. That's the difference between a dry, usable crawlspace and one you never want to enter.

  2. Jon R | | #2

    Consider using polyethylene (vs clay) to create the cap. In my experience, it works better.

    +1 on adding some fill to raise the level of the crawlspace floor.

    1. Joe Norm | | #5

      Good idea to use poly

  3. Walter Ahlgrim | | #3

    The first question is water coming out of your footing drain?

    If not either the pipes is blocked or the lowest point in the crawl space is lower than the highest point if the drain.

    You may find this old thread interesting

    https://www.greenbuildingadvisor.com/question/water-in-my-crawlspace
    https://www.greenbuildingadvisor.com/question/update-water-in-my-crawlspace

    This is a copy from that thread.
    If your pipe is dry and installed below the top of your slab it is hard to understand how you could have water in the crawlspace.

    The best drain would be installed so the top of the pipe is below the top of the footing see photo #5. This rarely happens as it is a lot of work. The footing concrete form is often dirt. No one wants to dig next the footer and make room for the drain.
    What happen most often is the drain is set on top of the footing see photo #7 this works as long as bottom of the drain is below the top of the basement floor. To elevate the slab the contractor must fill the basement with gravel so top of the slab is above the drain pipe.

    If your slab was installed level with the footing the drains will be dry and the basement will be wet.

    I like this article
    https://pro.homeadvisor.com/article.show.Foundation-Drainage.13702.html

    1. Joe Norm | | #6

      After reading these comments I know for sure at least one problem is that the floor is at the same level as the drain. The perplexing thing is I also know this is normal practice around here. My guess is that typically the soils are so well drained it never poses a problem.

  4. Expert Member
    Peter Engle | | #8

    Joe,
    "Local Practice" can often be wrong and sometimes even dumb. You've already guessed at one reason. The practice of leaving the crawl floor even with the bottom of the footer might work just fine on sandy soils, but terribly on dense soils. That's why our building codes are (generally) thought out to work in all climates, soils, and other variables. Or that's the goal anyhow.

    It is sometimes possible to load stone into a crawl space through a chute and a hatch in the wall. It' still a LOT of work to move the stone around the crawl with a rake, but depending on size, it can be possible. You can also break out hatches in several places and move the chute.

    The foundation drain you described in the OP pretty much IS a curtain drain. It's got drain pipe at the bottom surrounded by stone, and a stone curtain extending up to the surface. It just didn't go quite deep enough (or your floor is just a bit too deep). Raise the floor, install gutters, problem solved.

  5. Joe Norm | | #9

    Peter,

    I absolutely agree about "local practice." But I will say it is really hard to tell a professional who's been doing something in the area successfully for a very long time that what they are doing will not work.

    But on to the solutions.....people are suggesting filling in the crawl space. It seems to me this material would have to be of the same dense clayey parent material that the footers are sitting on. If I put is stone wouldn't the water still be there, just sitting under the stone bed?

    What if I was to pack as much parent soil around the wet portion of the footer to raise the level of the soil where it needs to be raised. Raising the level of the entire 1100 sqft footprint is a daunting task. One way to do it would be to cut many hatches in the subfloor and dump wheelbarrows from there. Yikes.

    I wish I had this vital piece of information 4 months ago when there was not a house capping the foundation. Live and learn.

  6. Expert Member
    Peter Engle | | #10

    If you fill it with stone then yes, the water will occasionally still be sitting there. But if the stone is capped with a vapor barrier and concrete, then that water won't hurt anything. And it will only be there after big storms. And, once you fix the gutter issue, there won't be nearly as much water there.

    How much clearance is there right now between the top of the soil and the bottom of the floor joists?

  7. Joe Norm | | #11

    There is 30” of space. Around here excavators typically dig the entire crawl space flat if they’re not on rock. Footers and stemwall often poured as a mono pour. Drains set level with bottoms of footer and away they go. Inside of crawl never gets filled. Makes a lot of sense to do what you’re suggesting. Surely must come down to extra cost.

    Thanks for the replies, I feel like I will be able to control the issue with the means we’ve discussed. Gutters will hopefully be on this week, transporting all that water far away. What has made me nervous is this is obviously just the beginning of the rain, even if it has been a remarkably wet September around here.

    Is water at bottoms of footers not a problem structurally? That’s why a pre drain seemed appealing, to actually dry out the footer with s curtain drain dig lower than the footer. It wouldn’t actually be a hard job for an excavator, and daylighting is very easy on this site. Thanks again

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