I am beginning the installation of a Crawlspace Perimeter drain. I discovered that the concrete footing extends about 12" into the crawlspace. As I was going to place the NDS EZ drain pipe down next to the footing my question is:

Is it okay to lay the drain pipe on top of this concrete shelf? This would be about 6 to 8 inches below the ground level in the crawlspace. The foundation blocks are on top of this concrete footing anyway. The concrete footing is about 10 to 12 inches thick and the only other option would be to dig down to the bottom of the footing and then tunnel under with the exit drain, which I'm not sure I can do anyway.


I haven't talked to the rep about this as I have since decided on a different type drainage pipe that is much, much cheaper. The reason I'm installing the pipe inside the crawlspace is because it is impossible to install it the full perimeter of the house on the exterior due to a large amount of concrete in driveways and parking areas, patios, and AC pads that surround the house. Plus, since the water seeps in at the foundation and isn't a large amount if it isn't allowed to accumulate, I can catch the water as it enters and channel it to the disharge drains.

Thanks for your input and suggestions. There's never only one way to do anything and I welcome any and all suggestions.

3 Answers 3


Have you tried contacting NDS directly and asking for their advice/recommendation? Contact NDS

I'm suggesting the above as it is my understanding that their product is only for "external" property use ie On the outside of your crawlspace/foundation wall.

Below added after reading @Kenneth (feedback) comment:

  • Dig a trench as wide as the manufactures recommendation and down to the top of the existing foundation.
  • Lay 50mm (2inch) of pea-gravel in the bottom of the trench.
  • Lay drain pipe on top of pea-gravel.
  • Back fill the rest of the trench with pea-gravel.
  • I understand from NDS EZ brochures they state their drainage system is a gravel free solution, but I highly recommend back filling the trench in your particular situation with pea-gravel.

    You can then breakout the foundation blocks locally (for a nice clean job I would use a core cutter, the foundation blocks will then naturally arch the opening you've made) to connect the new drainage system into an appropriate existing drainage system.

    • Yes. I have had an NDS representative inspect the crawlspace under my home and this was their recommendation. The EZ flow isn't outdoor specific as it is designed for drainage. It doesn't make any difference whether it is outside or inside the crawlspace as long as it is installed properly. The rep's company would have installed it themselves for a mere $8,000 bucks. Somewhat steep for my fixed income as I can do it myself for $1044. Thanks for your answer and suggestion. Commented Jul 1, 2011 at 19:18
    • @Kenneth, when I said "their product is only for "external" property use" I meant it was my understanding their product was designed/meant as a prevention barrier to water entering a building space (not as a means of getting water out of a building space, but if NDS say differently I stand corrected. Also, will NDS not answer your installation question? If no, I must say that represents terrible customer service from them...
      – Mike Perry
      Commented Jul 2, 2011 at 14:20

    Thanks for the input. I will be draining to a 4" drain line which will cross the yard to a ditch where the dishcharge will then be carried on down the line. And I will be using a core bit to drill a hole through the block and brick foundation. I like to keep everything neat and professional looking.

    I am using another type of pipe which is also gravel free because placing pea gravel or any other kind of rock in my situation is out of the question. However, from my observations and from listening to individuals and contractors who have used this pipe, it works like it should in our area with our kind of soil without any problems when installed with proper grade fall and using the proper fittings that come with the pipe.

    There are no underground springs. The water just comes in under the foundation in the fall and spring of the year and then only during extremely heavy rainfalls when the ground is already saturated. It isn't a year round thing and the water volume isn't extremely large. I just don't want any of it under there as I'm planning on lining the entire crawlspace with a very thick vapor barrier that will seal the entire area and I don't want a small amount of water to create any problems afterwards.


    As long as the drainage (which is basically a "french drain", no matter what fancy manufacturers call it) is below the exterior grade, I think you're fine. Don't forget that water does not flow uphill and you need to either trench along the outside of the property to a point lower than the grade of the pipe, or you need to drain it into a sump and use a sump pump to get it well away from your foundation, hopefully flowing downhill and away.

    The previous advice about using pea gravel, then drainage tube or pipe, hopefully with a sediment sock, then backfilling with MORE pea gravel is very good advice. We lived in an area of Oregon called "Hidden Springs" ... and guess what? There were hidden springs popping up all the time. One happened to be in the crawl space under our house. We hauled something like 5 cubic yards of pea gravel into the basement in buckets.

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