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

Lateral soil load?

user-1137156 | Posted in Building Code Questions on

I’m planning on using lightweight aggregate ( expanded clay/shale) as back-fill. This material has several benefits, it is about 10 times better insulation than other drainage mediums ( r 1/in to r2/in depending on density and moisture content) , it exerts about 60% of the lateral load of more conventional granular drainage materials it is also drains about 10 times faster. The disadvantage is it is more costly. Much of the cost could be recovered if the structure’s design were ” lightened” recognizing the lower lateral load. Is there a way the design values in the code can recognize the lower lateral load and allow a design based upon 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.


  1. user-2310254 | | #1


    Interesting idea. Did you see this study for the NC DOT?

    I suspect you will need to consult with a geotechnical or structural engineer on this one.

  2. user-1137156 | | #2

    Yes I had seen that study & it is one of the reasons for my question. The study clearly shows the design implications of using this type of material but the codes don't seem to allow foundation designs to take advantage of the properties of light weight fill.

  3. Expert Member
    Michael Maines | | #3

    The IRC building codes break soil into three classes for lateral loads, so prescriptively you could probably use the lowest of those three, depending on your code enforcement officer. It only affects vertical reinforcing schedules.

  4. user-2310254 | | #4

    [edit to correct last statement]

    I think you would need a way to control the lateral soil loads. This is usually done with some type of pressure-relief system. I've written about a few commercial projects where this sort of solution was used. But I suspect it would NOT make economic sense if building a typical home.

Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |