GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter X 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

Stem Wall Slab on Grade Detail Warm Climate

2008gt500 | Posted in General Questions on

So I went through the detail library, but most details are for up north.  I have a few questions on what is recommended.

1.  Floating slab or slab on shelf?  I found the attached detail online which shows the 2 options.

2.  Footer drains are not common at all here, are they really necessary?

3.  I’ll be going vertical on top of the poured concrete stem wall with ICF.  I’m assuming I can put my capillary break right on top of the stem wall and then pour the ICF walls on top of that.  Is there any reason to waterproof the footer with something like Fastfoot?

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.


  1. 2008gt500 | | #1

    Here's a quick sketch of what I am thinking. Leave the raw concrete stem wall, so it can dry to the outside above grade.

    I guess the last question I have is does it really matter if I have a cold joint between the footer and stem wall too? It's obviously much easier to do 2 pours.

  2. JC72 | | #2

    You could add rigid foam on the interior side of the stem wall which creates a thermal break between the stem wall and the slab. (See Gallery Pics)

  3. 2008gt500 | | #3

    Thanks John, looks like I will have something similar to what Carl did. I have some interesting bearing walls, so I was thinking of creating a bunch of mini slabs. through the house in between the stem walls. Not sure if I like this idea or think I will regret it if the different slabs settle causing uneven floors (I guess this is likely why most details have a shelf on the stem wall for the slab to sit on - like the left detail above). Is it more traditional to stem wall only the exterior and use standard footers inside?

Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |