GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

Stepped foundation

user-7521340 | Posted in Green Building Techniques on

Do do french drains on a stepped foundation look like? Our plans call for it but I can not find any examples online on how to do it.

GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.

Replies

  1. GBA Editor
    Brian Pontolilo | | #1

    Hi user-7521340 (it would be great to get your real name).

    Are you asking about footing drains? Like the drain shown in the illustration attached?

    1. user-7521340 | | #4

      Hi! Katie here :)

      Yes, thank you, I should have expanded my question! I was wondering what the drain looked like on the stepped portion of the foundation. Malcom answered my question:

      On a sloped site where the footing are stepped, the perimeter drains follow the footings, but on the vertical legs you use solid pipe, and reserve the perforated ones for the horizontal runs.

      Thank you!

  2. Expert Member
    Michael Maines | | #2

    Many people seem to think that French drains are something other than what they are--a relatively shallow trench filled with gravel and a drain tile or pipe, designed or popularized by Henry French: https://en.wikipedia.org/wiki/French_drain#History_and_construction.

    In any case, whether you mean footing drains, or French drains near the surface, you just smooth out the slope and let the drains follow the slope.

  3. Expert Member
    MALCOLM TAYLOR | | #3

    User...340,

    On a sloped site where the footing are stepped, the perimeter drains follow the footings, but on the vertical legs you use solid pipe, and reserve the perforated ones for the horizontal runs.

    1. user-7521340 | | #5

      That answers my question exactly, thank you!!

  4. jmfb_k7 | | #6

    I have a stepped footing situation as well, and our plans call for a drain running along the footer of our stem wall (walkout side). I am running into a problem in that at that depth I am not able to make it to daylight. I have about 3' of dropoff @ 75 feet out that I can daylight the upper footings with plenty of slope. We'll also have interior tile (connected through the footings) running into a sump pit for backup.
    If we go another 4 feet down for the stem wall, we'll be below the daylight exit, and our sump pit will only be 30" deep so I cannot route it to that.
    Do I raise the stem wall tile so it is below the slab but still has enough pitch for daylight, and just live with a underwater footing for that side of the house? Or do I need an extra-deep sump pit and pump it to keep the frost area dry?
    We have a high seasonal water table (low perc soil), so a few months out of the year we'll have a constant trickle of water out of these drains.
    This may only be temporary as well as there are some wetlands beyond the drop-off that will let me get even lower but I need to work through the permitting to get permission to drain out to there (I'll lay a tile next to the stem footing so I can tap into it in the future).
    See the attached for reference (note we were going to insulate under the footings originally but have to scrap that idea as nobody around here has seen it done like that before :( so insulation will now end at the top of the footers and we live with the thermal bridge. We plan to put a capillary break between the walls and footing, and tie it into the waterproofing and underslab vapor barrier to keep the stem wall and insulation dry, but if that stem wall is always dipping in water will that eventually fail and start wicking up the moisture?

Log in or create an account to post an answer.

Community

Recent Questions and Replies

  • |
  • |
  • |
  • |